Acetaminophen; caffeine is an oral analgesic indicated for the relief of mild pain due to cold and flu, dental pain, headache, myalgia, osteoarthritis, or sore throat. Caffeine is included to enhance analgesic efficacy. Acetaminophen possesses analgesic and antipyretic activity similar to aspirin; however, acetaminophen has no peripheral anti-inflammatory activity or effects on platelet function. It is effective in the relief of both acute and chronic pain and may be preferred over nonsteroidal anti-inflammatory drugs (NSAIDs) in certain patients due to fewer hematologic, gastrointestinal, and renal effects. Acetaminophen is the analgesic/antipyretic of choice for episodic use in patients with underlying renal disease; however, chronic use in this population is discouraged. Acetaminophen has a history of safe and effective use; however, unintentional or intentional misuse of acetaminophen is the leading cause of acute hepatic failure in the U.S.
General Administration Information
For storage information, see the specific product information within the How Supplied section.
Route-Specific Administration
Oral Administration
-Administer without regard to food.
This monograph discusses adverse reactions with acetaminophen; caffeine combination products. Clinicians may wish to consult the individual monographs for more information about each agent.
Overuse of drugs for treating acute headaches, including acetaminophen; caffeine, may lead to medication overuse headache. Patients may experience migraine-like daily headaches or a significant increase in migraine attack frequency. Discontinuation of the overused drug and treatment of withdrawal symptoms (e.g., transient worsening of headache) may be necessary. Advise patients about the risks of medication overuse (e.g., use of acetaminophen; caffeine for at least 15 days/month or any combination of therapy for at least 10 days/month) and encourage them to keep a written record of headache frequency and drug use. Pediatric guidelines recommend no more than 14 days/month of over-the-counter medication and no more than 9 days/month of any combination of therapy to avoid medication overuse headache. Caffeine is a CNS stimulant. Many adverse reactions to caffeine are an extension of caffeine's pharmacologic actions. At therapeutic or nontoxic doses, caffeine can commonly cause nervousness, mild tremor, and heightened attentiveness. Less frequent adverse reactions with usual consumption also include excitement, irritability, insomnia, headache, and muscle twitches. After excessive doses, caffeine can cause considerable anxiety. Seizures and delirium are also possible. A distinct caffeine withdrawal syndrome has been described. Patients who consume or receive caffeine daily for several weeks experience notable physical and psychiatric responses including lethargy, anxiety, dizziness, or rebound headache upon caffeine withdrawal.
Caffeine can stimulate gastric secretions and may cause GI upset (dyspepsia), nausea, loose stools, and may aggravate gastroesophageal reflux disease (GERD). Occasionally diarrhea is reported. The mild dehydration that caffeine produces may aggravate constipation. Excessive caffeine intake or intoxication may cause vomiting along with other signs of caffeine intoxication.
The hepatic effects of acetaminophen are well-known. In a study of combined data collected over a 5-year period (1998 to 2003) from 22 specialty medical centers in the United States, acetaminophen-induced liver injury was the leading cause of acute hepatic failure. Unintentional overdose accounted for almost half of the reported cases; acetaminophen toxicity may occur as the result of acute overdose or chronic excessive dosing. Young children appear to be at less risk of developing hepatotoxicity, possibly because of an age-related difference in the metabolism of the drug. Acetaminophen-induced hepatotoxicity is manifested as hepatic necrosis, jaundice, and hepatic encephalopathy. Early nonspecific symptoms include nausea/vomiting, anorexia, abdominal pain, and malaise. After acute overdose, elevated hepatic enzymes occur within 12 to 36 hours and maximal liver damage and hepatic impairment peak 3 to 5 days after ingestion. GI bleeding can occur secondary to hypoprothrombinemia. Administration of intravenous vitamin K is recommended for hypoprothrombinemia due to acetaminophen overdosage. If more than 150 to 200 mg/kg, 10 g, or an unknown amount of acetaminophen is ingested, obtain a serum acetaminophen concentration 4 hours after ingestion or as soon as possible thereafter. Promptly administer N-acetylcysteine (NAC), which serves as a substitute sulfhydryl donor for glutathione, if the acetaminophen concentration plots above the treatment line on the Rumack-Matthew nomogram. Begin NAC treatment immediately if the estimated time after ingestion approaches 8 hours. Acetaminophen misuse should be avoided; do not exceed recommended doses and account for intake from all sources (e.g., single-entity products and combination products). Excessive acetaminophen exposure, malnutrition, concurrent ethanol consumption (acute and chronic), and/or concurrent use of enzyme-inducing drugs (e.g., isoniazid) may lead to greater exposure of the toxic metabolite, N-acetyl-para-benzoquinone imine (NAPQI), and increase the risk for toxicity.
Acetaminophen has been associated with chronic analgesic nephropathy, a condition characterized by interstitial nephritis and renal papillary necrosis in patients receiving large doses of analgesics for an extended period of time. Though the National Kidney Foundation states there is negligible evidence to suggest chronic acetaminophen use causes analgesic nephropathy, they have recognized a weak association between chronic use and the prevalence of chronic renal failure (unspecified) and end-stage renal disease. In addition, acetaminophen overdose can result in acute renal failure and renal tubular necrosis, though such toxicity rarely occurs without severe hepatic toxicity. The risk of renal complications appears to be higher in patients with poor nutrition, chronic alcohol consumption, or concurrent use of enzyme-inducing drugs (e.g., isoniazid). Caffeine is a mild diuretic and patients may have increased urinary frequency. Polyuria can occur. Increased creatinine clearance and increased urinary calcium (hypercalciuria) and sodium excretion are reported in the literature.
Sporadic case reports of agranulocytosis, thrombocytopenia, thrombocytosis, neutropenia, and pancytopenia have been described in patients taking acetaminophen. Acetaminophen sulfate, a metabolite of acetaminophen, may rarely cause immune-mediated thrombocytopenia. Promptly investigate symptoms such as unusual tiredness or weakness, unusual bleeding or bruising, and unexplained sore throat or fever.
Drug-induced hemolysis and hemolytic anemia have been associated with acetaminophen overdose in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency. Though several case reports of hemolytic anemia in G6PD-deficient patients receiving therapeutic doses of acetaminophen exist, a direct cause and effect relationship has not been well established. Monitor G6PD-deficient patients presenting with acetaminophen toxicity closely for signs and symptoms of hemolysis.
Acetaminophen has been associated with a risk of rare but serious and sometimes fatal skin reactions, including Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and acute generalized exanthematous pustulosis (AGEP). These reactions can occur at any time during acetaminophen use, even after the first dose. SJS and TEN usually begin with flu-like symptoms followed by rash, blistering, and sloughing, all of which spread from the face downwards to the entire body (including palms of hands and soles of feet); recovery ranges from weeks to months and complications include corneal ulcerations, blindness, and internal organ damage. AGEP is typically a less severe reaction, characterized by acute onset, fever, and nonfollicular pustules on an erythematous rash; it usually resolves within 2 weeks of drug discontinuation. In addition to the aforementioned skin reactions, multiple cases of allergic contact dermatitis (delayed hypersensitivity type) have been reported in the literature. Various reactions, including generalized pruriginous micropapular eruption, facial edema, generalized pruriginous exanthem, exfoliative dermatitis, and generalized exanthema occurred within several hours after acetaminophen ingestion. Hypersensitivity reactions to acetaminophen may be manifested by urticaria, erythema, rash, maculopapular rash, and fever. Though rare, anaphylactic shock, angioedema, and anaphylactoid reactions have been reported. Patients who develop dermatologic or hypersensitivity reactions should discontinue acetaminophen immediately and seek medical attention for symptomatic treatment.
A case of acquired purpura fulminans developed in a 32-year-old woman who was instructed to take acetaminophen 1,000 mg every 4 to 6 hours as needed for pain. The patient noted rapidly spreading purpuric lesions and associated edema. Her lesions were nonblanchable and enlarging, and she had multiple purplish-black hemorrhagic and necrotic areas. Purpura fulminans is usually associated with disseminated intravascular coagulation and can occur in patients with inherited or acquired deficiencies of the protein C anticoagulant pathway. Based on the patient's history of alcohol use and poor nutritional status, the authors concluded that reduced hepatic glutathione stores were further reduced by the introduction of acetaminophen, leading to impaired protein C and S synthesis and propagation of the disseminated intravascular coagulation cascade. Discontinuation of alcohol and acetaminophen and administration of vitamin K, heparin, and a systemic antibiotic led to almost complete purpuric lesion and hepatotoxicity resolution in 6 days.
Acetaminophen-induced rhabdomyolysis has been described in a single case report. A 17-year-old male with a past medical history of drug-induced reactions (hepatitis, agranulocytosis, desquamative dermatitis, and pyrexia) after receiving acetaminophen with or without concurrent antibiotics, was re-challenged with oral acetaminophen 400 mg. Within 5 hours of administration, the adolescent presented with febrile exanthema, neutropenia, and increased C-reactive protein, creatine phosphokinase, tumor necrosis factor-alpha, interleukin-6, and interleukin-10; the skin eruption and fever lasted 36 hours. Symptoms such as unusual tiredness, weakness or unusual pain and swelling of the extremities, nausea and vomiting, and dark-colored urine should be investigated promptly.
Prospective studies have shown there to be a slight but consistent association between regular analgesic use and hearing loss. Acetaminophen-related ototoxicity may result from depletion of glutathione, which protects the cochlea from noise damage. As a true long-term association may exist, counsel patients to minimize long-term treatment with acetaminophen as much as possible. A prospective analysis examining the association between analgesic use and the risk of hearing loss was conducted in 62,261 women 31 to 48 years of age at study enrollment who were originally enrolled in the Nurses' Health Study II. The association between self-reported hearing loss and analgesic use (including acetaminophen, aspirin, and NSAIDs) was examined over 14 years. During 764,247 person-years of follow-up, 10,012 cases of hearing loss were reported. After adjustment for confounders, acetaminophen use 2 or more days per week was independently associated with an increased risk of hearing loss, with the relative risk of hearing loss increasing with increasing frequency of use. Acetaminophen use 2 to 3, 4 to 5, or 6 or more days per week was associated with relative risks of 1.11 (95% CI 1.02 to 1.19), 1.21 (95% CI 1.07 to 1.37), and 1.08 (95% CI 0.95 to 1.22), respectively (p = 0.0007). Of note, those with more frequent use of acetaminophen had higher body mass indices; were more likely to smoke, have hypertension, or have diabetes; and were less physically active. In a similar study in male patients, the association between professionally diagnosed hearing loss and analgesic use (including acetaminophen, aspirin, and NSAIDs) was prospectively analyzed in 26,917 patients 40 to 74 years of age at study enrollment over 18 years. During 369,079 person-years of follow-up, 3,488 cases of hearing loss were reported. After adjustment for confounders, the hazard ratio (HR) for acetaminophen-associated hearing loss was 1.22 (95% CI 1.07 to 1.39, p = 0.09) in patients who were regular users of the drug (at least 2 times weekly) compared to those with less use. Men who regularly used acetaminophen for 4 years or more were 33% (14% to 56%) more likely to develop hearing loss than those with shorter use. In men younger than 50 years, the HR of hearing loss was 1.99 (95% CI 1.34 to 2.95); the degree of association generally decreased with aging. These studies do suggest association; however, data are based on patient reporting of the outcomes. Information regarding noise exposure and analgesic doses was not provided.
Adverse events to caffeine that have been described in the published literature include alterations in serum glucose such as hypoglycemia and hyperglycemia.
Too much caffeine may occasionally cause rapid heartbeat. Cardiovascular effects of caffeine have been reported in the literature (i.e., palpitations, sinus tachycardia, increased left ventricular output, and increased stroke volume).
This monograph discusses the contraindications/precautions of acetaminophen; caffeine combination products. Clinicians may wish to consult the individual monographs for more information about each agent.
Acetaminophen is contraindicated in patients with a known acetaminophen hypersensitivity or hypersensitivity to any of the excipients of the formulation to be used. Acetaminophen hypersensitivity reactions are rare, but severe sensitivity reactions are possible. Patients who have experienced a serious skin reaction with acetaminophen should not take the drug again; discuss alternative pain relievers with these patients.
Acetaminophen has the potential for overdose or poisoning causing hepatotoxicity and acute liver failure, at times resulting in liver transplantation and death. Most cases of liver injury are associated with the use of acetaminophen at doses exceeding 4 g per day and often involve the use of more than 1 acetaminophen-containing product. Caution must be used in the measurement of oral liquid dosage forms to minimize the risk of dosing errors that can result in accidental overdose. Advise patients receiving acetaminophen to carefully read OTC labels, to avoid excessive and/or duplicate medications, and to seek medical help immediately if more than 4 g of acetaminophen is ingested in 1 day, even if they feel well. It is important to note that the risk of acetaminophen-induced hepatotoxicity is increased in patients with pre-existing hepatic disease (e.g., hepatitis), those who ingest alcohol (e.g., ethanol intoxication, alcoholism), those with chronic malnutrition, and those with severe hypovolemia. In patients with chronic hepatic disease, acetaminophen can be used safely in recommended doses and is often preferred to nonsteroidal anti-inflammatory drugs (NSAIDs) due to the absence of platelet impairment, gastrointestinal toxicity, and nephrotoxicity. Though the half-life of acetaminophen may be prolonged, repeated dosing does not result in drug or metabolite accumulation. In addition, cytochrome P450 activity is not increased and glutathione stores are not depleted in hepatically impaired patients taking therapeutic doses, therefore toxic metabolite formation and accumulation is not altered. Although it is always prudent to use the smallest dose of acetaminophen for the shortest duration necessary, courses less than 2 weeks in length have been administered safely to adult patients with stable chronic liver disease. Use caffeine cautiously in patients with hepatic disease or hepatic impairment. Caffeine clearance may be delayed, leading to toxicity.
Use acetaminophen with caution in patients with severe renal impairment or renal failure. Do not administer acetaminophen any more frequently than every 8 hours in patients with a CrCl less than 10 mL/minute. Some studies have suggested an association between chronic use of acetaminophen and renal effects. The National Kidney Foundation states that there is negligible evidence to suggest chronic use of acetaminophen causes analgesic nephropathy; however, there is a weak association between chronic acetaminophen use and the prevalence of chronic renal failure and end-stage renal disease. In a case-controlled study of adult patients with early renal failure, the regular use of acetaminophen (without aspirin) was associated with a risk of chronic renal failure that was 2.5-times as high as that for non-acetaminophen users. The risk increased with an increasing cumulative acetaminophen lifetime dose. The average dose used during periods of regular acetaminophen use also correlated with risk, as those who took 1.4 g/day or more during periods of regular use had an odds ratio for chronic renal failure of 5.3; duration of therapy was unrelated to risk. The National Kidney Foundation considers acetaminophen as the non-narcotic analgesic of choice for episodic pain in patients with chronic renal disease, but discourages habitual consumption. Renal impairment or renal failure may also delay caffeine clearance.
Tobacco smoke contains hydrocarbons that induce hepatic CYP450 microsomal enzymes. Tobacco smoking induces the cytochrome P450 isoenzyme CYP1A2 and may potentially increase the risk for acetaminophen-induced hepatotoxicity during overdose via enhanced generation of acetaminophen's hepatotoxic metabolite, N-acetyl-p-benzoquinoneimine (NAPQI). In a retrospective chart review of 602 patients (13 to 86 years of age) admitted for acetaminophen toxicity, current daily tobacco use was registered in 70% of patients. Multivariant analyses found tobacco smoking to be an independent risk factor for hepatotoxicity, hepatic encephalopathy, and death. Tobacco smoking also has been shown to increase the clearance of caffeine. Passive smoke exposure may also cause an increase in caffeine clearance. Because the effect on hepatic microsomal enzymes is not related to the nicotine component of tobacco, sudden smoking cessation may result in a reduced clearance of caffeine, despite the initiation of nicotine replacement. Caffeine dosage may need to be reduced at the cessation of smoking.
Patients with G6PD deficiency who overdose with acetaminophen may be at increased risk for drug-induced hemolysis. Monitor at-risk patients for signs and symptoms of hemolysis. Conflicting data exists on whether therapeutic doses of acetaminophen can cause hemolysis in G6PD deficient patients. However, a direct cause and effect relationship has not been well established, and therefore, therapeutic doses are generally considered safe in this population.
Caffeine is a central nervous system stimulant and should be used with caution in patients with a seizure disorder.
Use caffeine cautiously in patients with cardiac disease or tachycardia. Caffeine can stimulate the force of myocardial contraction and can increase heart rate. It may increase left ventricular output and stroke volume. Too much caffeine, as a dietary supplement or in non-prescription medications, may occasionally cause rapid heartbeat.
Advise patients with diabetes mellitus to moderate their intake of caffeine. Although the effects are mild, caffeine can either raise or decrease blood sugar.
Caffeine has been shown to increase heart rate, left ventricular output, and stroke volume. Patients with hyperthyroidism may be sensitive to these cardiac effects and should moderate their caffeine intake. Closely read labels of non-prescription drugs and dietary supplements prior to use, since some products may contain caffeine.
Caffeine can stimulate gastric secretions and may aggravate gastroesophageal reflux disease (GERD). Clinical trial data are conflicting regarding the limitation of caffeine as an effective strategy to control GERD symptoms; however, recommended lifestyle modifications for patients with GERD often include moderation of caffeine intake.
Too much caffeine may cause nervousness, irritability, sleeplessness, and occasionally, rapid heartbeat. Patients with insomnia or anxiety disorders may be advised to moderate their caffeine intake. Because caffeine is an ingredient in some non-prescription products and dietary foods or supplements, patients should be advised to read labels carefully or check with their prescriber or pharmacist if they are unsure if a product contains caffeine.
Controlled clinical trials of acetaminophen; caffeine use during pregnancy are not available. Published epidemiological studies have not reported a clear association with acetaminophen use during pregnancy and birth defects, miscarriage, or adverse maternal or fetal outcomes. Large observational studies of newborns exposed to oral acetaminophen during the first trimester have not shown an increased risk for congenital malformations or major birth defects; however, these studies cannot definitely establish the absence of risk because of methodological limitations. Some studies have, however, shown an association between prenatal oral acetaminophen exposure and neurodevelopmental problems, including motor delays, attention problems, behavioral problems, and poorer early language development. Long term acetaminophen use, increased dose, and frequency are associated with a stronger association. Both the American College of Obstetricians and Gynecologists (ACOG) and Society for Maternal-Fetal Medicine (SMFM) recommend acetaminophen as the first-line pharmacological therapy for pain and/or fever during pregnancy; however, they do also recommend that acetaminophen be used cautiously at the lowest effective dose for the shortest possible time. Caffeine easily crosses the placenta; fetal blood and tissue concentrations approximate maternal concentrations. There are no large, well-controlled studies of caffeine administration during pregnancy; it is generally recommended that the intake of caffeine-containing beverages, like coffee, teas, and sodas, be limited in pregnancy (usually no more than 1 to 2 caffeine-containing beverages/day) or avoided if possible. Similarly, limit caffeine-containing medications to use only when absolutely necessary. Low to moderate caffeine intake does not appear to increase the risk of congenital malformation, spontaneous abortion, pre-term birth or low birth weight. The association between high daily intake (more than 500 mg/day) of caffeine and increased rates of low birth weight, spontaneous abortion, difficulty in getting pregnant or infertility is still controversial, as some studies have not controlled for concomitant cigarette smoking. Neonatal arrhythmias (e.g., tachycardia, premature atrial contractions) and tachypnea have been reported when caffeine was consumed during pregnancy in amounts more than 500 mg/day; caffeine withdrawal after birth may account for these symptoms.
Limited published studies report acetaminophen passes rapidly into human milk with similar concentrations in the milk and plasma. Average and maximum neonatal doses of 1% and 2%, respectively, of the weight-adjusted maternal dose are reported after a single oral dose of 1,000 mg. There is a well-documented report of rash occurring in a breast-fed infant that resolved with drug discontinuation and recurred with resumption. According to previous recommendations from the American Academy of Pediatrics (AAP), acetaminophen has not been associated with any observable changes in nursing infants of mothers that took acetaminophen while breast-feeding. The AAP and other experts regard acetaminophen as a maternal medicine that is usually compatible with breast-feeding. Cytochrome P450 metabolism of caffeine is inhibited in infants who are breast-fed; formula feeding does not appear to affect the pharmacokinetics of caffeine in infants. Peak caffeine milk concentrations usually occur within 1 hour after the maternal ingestion of a caffeinated beverage; with milk:plasma ratios of 0.5 to 0.7 reported. Although only small amounts are secreted in breast milk, caffeine can accumulate in the neonate if maternal ingestion is moderate to high. Higher caffeine intake (more than 500 mg/day) by a nursing mother may cause irritability or poor sleeping patterns in the infant who is breast-feeding. Use caffeine-containing drug products cautiously during lactation due to their high caffeine contents.
This monograph discusses the indications and dosage of acetaminophen; caffeine combination products. Clinicians may wish to consult the individual monographs for more information about each agent.
For the relief of mild pain due to cold and flu, dental pain, headache, myalgia, osteoarthritis, or sore throat:
Oral dosage (acetaminophen; caffeine 500 mg/65 mg tablets or caplets, e.g., Excedrin Tension Headache):
Adults: 2 tablets or caplets PO every 6 hours as needed. Do not exceed 6 tablets or caplets per day.
Children and Adolescents 12 to 17 years: 2 tablets or caplets PO every 6 hours as needed. Do not exceed 6 tablets or caplets per day.
Oral dosage (acetaminophen; caffeine 1,000 mg/65 mg per 60 mL oral solution, e.g., Goody's Headache Relief Shot):
Adults: 60 mL PO every 6 hours as needed. Do not exceed 240 mL per day.
Children and Adolescents 12 to 17 years: 60 mL PO every 6 hours as needed. Do not exceed 240 mL per day.
Maximum Dosage Limits:
-Adults
6 tablets or caplets/day PO; 240 mL oral solution/day PO. Do not exceed a total daily dose of 4 g acetaminophen from ALL sources.
-Geriatric
6 tablets or caplets/day PO; 240 mL oral solution/day PO. Do not exceed a total daily dose of 4 g acetaminophen from ALL sources.
-Adolescents
6 tablets or caplets/day PO; 240 mL oral solution/day PO. Do not exceed a total daily dose of 4 g acetaminophen from ALL sources.
-Children
Children 12 years: 6 tablets or caplets/day PO; 240 mL oral solution/day PO. Do not exceed a total daily dose of 4 g acetaminophen from ALL sources.
Children 1 to 11 years: Safety and efficacy have not been established.
-Infants
Safety and efficacy have not been established.
-Neonates
Safety and efficacy have not been established.
Patients with Hepatic Impairment Dosing
Use acetaminophen; caffeine with caution in patients with hepatic dysfunction. In patients with chronic hepatic disease, acetaminophen can be used safely; use the smallest dose for the shortest duration necessary. Hepatic impairment may also delay caffeine clearance.
Patients with Renal Impairment Dosing
For CrCl less than 10 mL/minute, administer acetaminophen at a minimum interval of every 8 hours. Discourage chronic use in patients with underlying renal disease. Renal impairment or renal failure may also delay caffeine clearance.
*non-FDA-approved indication
Abacavir; Lamivudine, 3TC; Zidovudine, ZDV: (Minor) Both acetaminophen and zidovudine, ZDV undergo glucuronidation. Competition for the metabolic pathway is thought to have caused a case of acetaminophen-related hepatotoxicity. This interaction may be more clinically significant in patients with depleted glutathione stores, such as patients with acquired immunodeficiency syndrome, poor nutrition, or alcoholism.
Acetaminophen; Aspirin, ASA; Caffeine: (Minor) Caffeine has been reported to increase the metabolism of aspirin.
Acetaminophen; Aspirin, ASA; Caffeine: (Minor) Caffeine has been reported to increase the metabolism of aspirin.
Acetaminophen; Aspirin: (Minor) Caffeine has been reported to increase the metabolism of aspirin.
Acetaminophen; Aspirin; Diphenhydramine: (Minor) Caffeine has been reported to increase the metabolism of aspirin.
Acetaminophen; Chlorpheniramine; Dextromethorphan; Phenylephrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants like phenylephrine; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Acetaminophen; Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Acetaminophen; Chlorpheniramine; Phenylephrine : (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants like phenylephrine; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Acetaminophen; Dextromethorphan; Guaifenesin; Phenylephrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants like phenylephrine; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Acetaminophen; Dextromethorphan; Guaifenesin; Pseudoephedrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Acetaminophen; Dextromethorphan; Phenylephrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants like phenylephrine; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Acetaminophen; Dextromethorphan; Pseudoephedrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Acetaminophen; Guaifenesin; Phenylephrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants like phenylephrine; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Acetaminophen; Phenylephrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants like phenylephrine; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Acetaminophen; Pseudoephedrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Aclidinium; Formoterol: (Moderate) Caffeine may enhance the cardiac inotropic effects of beta-agonists.
Acrivastine; Pseudoephedrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Acyclovir: (Moderate) Monitor for an increase in caffeine-related adverse reactions, including nervousness, irritability, insomnia, tachycardia, or tremor, if concomitant use of acyclovir is necessary; lower caffeine doses may be necessary. Concomitant use may increase caffeine exposure; caffeine is a CYP1A2 substrate and acyclovir is a CYP1A2 inhibitor.
Adenosine: (Major) Larger doses of adenosine may be required or adenosine may not be effective in the presence of methylxanthines. The effects of adenosine are antagonized by methylxanthines. When used for diagnostic purposes, instruct patients to avoid consumption of methylxanthine-containing products, including caffeinated beverages, for at least 5 half-lives prior to the imaging study.
Albuterol: (Moderate) Caffeine may enhance the cardiac inotropic effects of beta-agonists.
Albuterol; Budesonide: (Moderate) Caffeine may enhance the cardiac inotropic effects of beta-agonists.
Allopurinol: (Moderate) Monitor for an increase in caffeine-related adverse reactions, including nervousness, irritability, insomnia, tachycardia, or tremor, if concomitant use of allopurinol is necessary; lower caffeine doses may be necessary. Concomitant use may increase caffeine exposure; caffeine is a CYP1A2 substrate and allopurinol is a CYP1A2 inhibitor.
Alprazolam: (Minor) Patients taking benzodiazepines for insomnia should not use caffeine-containing products prior to going to bed as these products may antagonize the sedative effects of the benzodiazepine.
Aluminum Hydroxide: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
Aluminum Hydroxide; Magnesium Carbonate: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
Aluminum Hydroxide; Magnesium Hydroxide: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
Aluminum Hydroxide; Magnesium Hydroxide; Simethicone: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
Aluminum Hydroxide; Magnesium Trisilicate: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
Amantadine: (Major) Amantadine used concomitantly with psychostimulants, such as caffeine, can result in increased stimulant effects, such as nervousness, irritability, or insomnia, and can lead to seizures or cardiac arrhythmias. Close monitoring of the patient is recommended.
Amiodarone: (Moderate) Monitor for an increase in caffeine-related adverse reactions, including nervousness, irritability, insomnia, tachycardia, or tremor, if concomitant use of amiodarone is necessary; lower caffeine doses may be necessary. Concomitant use may increase caffeine exposure; caffeine is a CYP1A2 substrate and amiodarone is a CYP1A2 inhibitor.
Amobarbital: (Moderate) Caffeine has been reported to increase the metabolism of barbiturates, and barbiturates increase caffeine elimination. Higher caffeine doses may be needed after barbiturate administration. (Minor) Chronic therapy with barbiturates can increase the metabolism and decrease the effectiveness of acetaminophen. During acute overdoses, barbiturates can enhance the formation of toxic acetaminophen metabolites.
Amphetamine: (Moderate) Avoid excessive caffeine intake during use of the amphetamine salts. Caffeine is a CNS-stimulant and such actions are expected to be additive when coadministered with other CNS stimulants or psychostimulants. Excessive caffeine ingestion (via medicines, foods like chocolate, dietary supplements, or beverages including coffee, green tea, other teas, colas) may contribute to side effects like nervousness, irritability, nausea, insomnia, or tremor. Patients should avoid medications and dietary supplements which contain high amounts of caffeine.
Amphetamine; Dextroamphetamine Salts: (Moderate) Avoid excessive caffeine intake during use of the amphetamine salts. Caffeine is a CNS-stimulant and such actions are expected to be additive when coadministered with other CNS stimulants or psychostimulants. Excessive caffeine ingestion (via medicines, foods like chocolate, dietary supplements, or beverages including coffee, green tea, other teas, colas) may contribute to side effects like nervousness, irritability, nausea, insomnia, or tremor. Patients should avoid medications and dietary supplements which contain high amounts of caffeine.
Amphetamine; Dextroamphetamine: (Moderate) Avoid excessive caffeine intake during use of the amphetamine salts. Caffeine is a CNS-stimulant and such actions are expected to be additive when coadministered with other CNS stimulants or psychostimulants. Excessive caffeine ingestion (via medicines, foods like chocolate, dietary supplements, or beverages including coffee, green tea, other teas, colas) may contribute to side effects like nervousness, irritability, nausea, insomnia, or tremor. Patients should avoid medications and dietary supplements which contain high amounts of caffeine.
Anagrelide: (Moderate) Anagrelide has been shown to inhibit CYP1A2. In theory, coadministration of anagrelide with substrates of CYP1A2, including caffeine, could lead to increases in the serum concentrations of caffeine and, thus, adverse effects.
Antacids: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
Aprepitant, Fosaprepitant: (Minor) Use caution if acetaminophen and aprepitant are used concurrently and monitor for an increase in acetaminophen-related adverse effects for several days after administration of a multi-day aprepitant regimen. Acetaminophen is a minor (10 to 15%) substrate of CYP3A4. Aprepitant, when administered as a 3-day oral regimen (125 mg/80 mg/80 mg), is a moderate CYP3A4 inhibitor and inducer and may increase plasma concentrations of acetaminophen. For example, a 5-day oral aprepitant regimen increased the AUC of another CYP3A4 substrate, midazolam (single dose), by 2.3-fold on day 1 and by 3.3-fold on day 5. After a 3-day oral aprepitant regimen, the AUC of midazolam (given on days 1, 4, 8, and 15) increased by 25% on day 4, and then decreased by 19% and 4% on days 8 and 15, respectively. As a single 125 mg or 40 mg oral dose, the inhibitory effect of aprepitant on CYP3A4 is weak, with the AUC of midazolam increased by 1.5-fold and 1.2-fold, respectively. After administration, fosaprepitant is rapidly converted to aprepitant and shares many of the same drug interactions. However, as a single 150 mg intravenous dose, fosaprepitant only weakly inhibits CYP3A4 for a duration of 2 days; there is no evidence of CYP3A4 induction. Fosaprepitant 150 mg IV as a single dose increased the AUC of midazolam (given on days 1 and 4) by approximately 1.8-fold on day 1; there was no effect on day 4. Less than a 2-fold increase in the midazolam AUC is not considered clinically important.
Arformoterol: (Moderate) Caffeine may enhance the cardiac inotropic effects of beta-agonists.
Armodafinil: (Moderate) Caffeine is a CNS-stimulant and such actions are expected to be additive when coadministered with armodafinil. Caffeine should be used cautiously with armodafinil. Intake of caffeine should be limited. Excessive intake may cause nervousness, irritability, insomnia, or other side effects.
Articaine; Epinephrine: (Moderate) Caffeine is a CNS-stimulant and such actions are expected to be additive when coadministered with other CNS stimulants or psychostimulants. (Moderate) Coadministration of articaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue articaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Aspirin, ASA: (Minor) Caffeine has been reported to increase the metabolism of aspirin.
Aspirin, ASA; Butalbital; Caffeine: (Moderate) Caffeine has been reported to increase the metabolism of barbiturates, and barbiturates increase caffeine elimination. Higher caffeine doses may be needed after barbiturate administration. (Minor) Caffeine has been reported to increase the metabolism of aspirin. (Minor) Chronic therapy with barbiturates can increase the metabolism and decrease the effectiveness of acetaminophen. During acute overdoses, barbiturates can enhance the formation of toxic acetaminophen metabolites.
Aspirin, ASA; Caffeine: (Minor) Caffeine has been reported to increase the metabolism of aspirin.
Aspirin, ASA; Caffeine; Orphenadrine: (Minor) Caffeine has been reported to increase the metabolism of aspirin.
Aspirin, ASA; Carisoprodol; Codeine: (Minor) Caffeine has been reported to increase the metabolism of aspirin.
Aspirin, ASA; Citric Acid; Sodium Bicarbonate: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected. (Minor) Caffeine has been reported to increase the metabolism of aspirin.
Aspirin, ASA; Dipyridamole: (Major) Methylxanthines, through antagonism of adenosine and thus pharmacologic-induced coronary vasodilation, have been associated with false-negative results during dipyridamole-thallium 201 stress testing. It is recommended that methylxanthines (caffeine, caffeinated beverages and foods, theophylline, etc.) be discontinued for at least 24 hours prior to stress testing. An interaction is not expected when methylxanthines are used concomitantly with chronic dipyridamole therapy. (Minor) Caffeine has been reported to increase the metabolism of aspirin.
Aspirin, ASA; Omeprazole: (Minor) Caffeine has been reported to increase the metabolism of aspirin.
Aspirin, ASA; Oxycodone: (Minor) Caffeine has been reported to increase the metabolism of aspirin.
Barbiturates: (Moderate) Caffeine has been reported to increase the metabolism of barbiturates, and barbiturates increase caffeine elimination. Higher caffeine doses may be needed after barbiturate administration. (Minor) Chronic therapy with barbiturates can increase the metabolism and decrease the effectiveness of acetaminophen. During acute overdoses, barbiturates can enhance the formation of toxic acetaminophen metabolites.
Benzodiazepines: (Minor) Patients taking benzodiazepines for insomnia should not use caffeine-containing products prior to going to bed as these products may antagonize the sedative effects of the benzodiazepine.
Benzphetamine: (Moderate) Avoid excessive caffeine intake during use of benzphetamine. Caffeine is a CNS-stimulant and such actions are expected to be additive when coadministered with other CNS stimulants or psychostimulants. Excessive caffeine ingestion (via medicines, foods like chocolate, dietary supplements, or beverages including coffee, green tea, other teas, colas) may contribute to side effects like nervousness, irritability, nausea, insomnia, or tremor. Patients should avoid medications and dietary supplements which contain high amounts of caffeine.
Beta-agonists: (Moderate) Caffeine may enhance the cardiac inotropic effects of beta-agonists.
Brompheniramine; Dextromethorphan; Phenylephrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants like phenylephrine; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Brompheniramine; Phenylephrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants like phenylephrine; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Brompheniramine; Pseudoephedrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Brompheniramine; Pseudoephedrine; Dextromethorphan: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Budesonide; Formoterol: (Moderate) Caffeine may enhance the cardiac inotropic effects of beta-agonists.
Budesonide; Glycopyrrolate; Formoterol: (Moderate) Caffeine may enhance the cardiac inotropic effects of beta-agonists.
Bupivacaine Liposomal: (Moderate) Coadministration of bupivacaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue bupivacaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Bupivacaine: (Moderate) Coadministration of bupivacaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue bupivacaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Bupivacaine; Epinephrine: (Moderate) Caffeine is a CNS-stimulant and such actions are expected to be additive when coadministered with other CNS stimulants or psychostimulants. (Moderate) Coadministration of bupivacaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue bupivacaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Bupivacaine; Lidocaine: (Moderate) Coadministration of bupivacaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue bupivacaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen. (Moderate) Coadministration of lidocaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue lidocaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Bupivacaine; Meloxicam: (Moderate) Coadministration of bupivacaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue bupivacaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Bupropion: (Moderate) Bupropion is associated with a dose-related risk of seizures. Excessive use of psychostimulants, including caffeine, is associated with an increased seizure risk and may increase this risk during the concurrent use of bupropion. Carefully consider a patient's caffeine intake from all sources, including medicines. Monitor for irritability, tremor, increased blood pressure, insomnia and seizures. Many non-prescription medicines and weight loss aids may contain caffeine and patients should read labels carefully. Examples of foods and beverages containing caffeine include coffee, teas, colas, energy drinks, chocolate, and some herbal or dietary supplements. Patients should be advised to limit excessive caffeine intake during bupropion therapy.
Bupropion; Naltrexone: (Moderate) Bupropion is associated with a dose-related risk of seizures. Excessive use of psychostimulants, including caffeine, is associated with an increased seizure risk and may increase this risk during the concurrent use of bupropion. Carefully consider a patient's caffeine intake from all sources, including medicines. Monitor for irritability, tremor, increased blood pressure, insomnia and seizures. Many non-prescription medicines and weight loss aids may contain caffeine and patients should read labels carefully. Examples of foods and beverages containing caffeine include coffee, teas, colas, energy drinks, chocolate, and some herbal or dietary supplements. Patients should be advised to limit excessive caffeine intake during bupropion therapy.
Busulfan: (Moderate) Use busulfan and acetaminophen together with caution; concomitant use may result in increased busulfan levels and increased busulfan toxicity. Separating the administration of these drugs may mitigate this interaction; avoid giving acetaminophen within 72 hours prior to or concurrently with busulfan. Busulfan is metabolized in the liver through conjugation with glutathione; acetaminophen decreases glutathione levels in the blood and tissues and may reduce the clearance of busulfan.
Butalbital; Acetaminophen: (Moderate) Caffeine has been reported to increase the metabolism of barbiturates, and barbiturates increase caffeine elimination. Higher caffeine doses may be needed after barbiturate administration. (Minor) Chronic therapy with barbiturates can increase the metabolism and decrease the effectiveness of acetaminophen. During acute overdoses, barbiturates can enhance the formation of toxic acetaminophen metabolites.
Butalbital; Acetaminophen; Caffeine: (Moderate) Caffeine has been reported to increase the metabolism of barbiturates, and barbiturates increase caffeine elimination. Higher caffeine doses may be needed after barbiturate administration. (Minor) Chronic therapy with barbiturates can increase the metabolism and decrease the effectiveness of acetaminophen. During acute overdoses, barbiturates can enhance the formation of toxic acetaminophen metabolites.
Butalbital; Acetaminophen; Caffeine; Codeine: (Moderate) Caffeine has been reported to increase the metabolism of barbiturates, and barbiturates increase caffeine elimination. Higher caffeine doses may be needed after barbiturate administration. (Minor) Chronic therapy with barbiturates can increase the metabolism and decrease the effectiveness of acetaminophen. During acute overdoses, barbiturates can enhance the formation of toxic acetaminophen metabolites.
Butalbital; Aspirin; Caffeine; Codeine: (Moderate) Caffeine has been reported to increase the metabolism of barbiturates, and barbiturates increase caffeine elimination. Higher caffeine doses may be needed after barbiturate administration. (Minor) Caffeine has been reported to increase the metabolism of aspirin. (Minor) Chronic therapy with barbiturates can increase the metabolism and decrease the effectiveness of acetaminophen. During acute overdoses, barbiturates can enhance the formation of toxic acetaminophen metabolites.
Caffeine: (Moderate) Certain foods that contain high amounts of caffeine or theobromine should be limited during the therapeutic use of caffeine in order to limit additive methylxanthine effects. While taking Caffeine-containing medicines, limit the use of foods, beverages (examples: coffee, tea, colas), herbs (examples: guarana, green tea) and other products that contain additional caffeine, such as chocolate and some non-prescription medications or dietary supplements for headache, insomnia, or weight loss. Too much Caffeine can cause effects like nausea, nervousness, or sleeplessness. Some drug products for adults that contain caffeine have about as much caffeine as a cup of coffee.
Calcium, Magnesium, Potassium, Sodium Oxybates: (Moderate) Caffeine should be avoided or used cautiously with oxybates. Monitor for potential side effects such as nervousness, irritability, insomnia, and/or cardiac arrhythmias.
Cannabidiol: (Moderate) Consider a dose reduction of caffeine as clinically appropriate, if adverse reactions occur when administered with cannabidiol. Increased caffeine exposure is possible. Caffeine is a CYP1A2 substrate and cannabidiol is a weak CYP1A2 inhibitor.
Capmatinib: (Moderate) Monitor for an increase in caffeine-related adverse reactions, including nervousness, irritability, insomnia, tachycardia, or tremor, if concomitant use of capmatinib is necessary; lower caffeine doses may be necessary. Concomitant use may increase caffeine exposure; caffeine is a CYP1A2 substrate and capmatinib is a CYP1A2 inhibitor. Coadministration with capmatinib increased caffeine exposure by 134%.
Carbamazepine: (Minor) Carbamazepine may induce caffeine metabolism via induction of the hepatic CYP1A2 isoenzyme. (Minor) Carbamazepine may potentially accelerate the hepatic metabolism of acetaminophen. In addition, due to enzyme induction, carbamazepine may increase the risk for acetaminophen-induced hepatotoxicity via generation of a greater percentage of acetaminophen's hepatotoxic metabolite, NAPQI. Clinicians should be alert to decreased effect of acetaminophen. Dosage adjustments may be necessary, and closer monitoring of clinical and/or adverse effects is warranted.
Cetirizine; Pseudoephedrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Charcoal: (Minor) Activated charcoal binds many drugs within the gut. Administering charcoal dietary supplements at the same time as a routine acetaminophen dosage would be expected to interfere with the analgesic and antipyretic efficacy of acetaminophen. Charcoal is mostly used in the setting of acetaminophen overdose; however, patients should never try to treat an acetaminophen overdose with charcoal dietary supplements. Advise patients to get immediate medical attention for an acetaminophen overdose.
Chlophedianol; Dexchlorpheniramine; Pseudoephedrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Chlordiazepoxide: (Minor) Patients taking benzodiazepines for insomnia should not use caffeine-containing products prior to going to bed as these products may antagonize the sedative effects of the benzodiazepine.
Chlordiazepoxide; Amitriptyline: (Minor) Patients taking benzodiazepines for insomnia should not use caffeine-containing products prior to going to bed as these products may antagonize the sedative effects of the benzodiazepine.
Chlordiazepoxide; Clidinium: (Minor) Patients taking benzodiazepines for insomnia should not use caffeine-containing products prior to going to bed as these products may antagonize the sedative effects of the benzodiazepine.
Chloroprocaine: (Moderate) Coadministration of chloroprocaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue chloroprocaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Chlorpheniramine; Dextromethorphan; Phenylephrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants like phenylephrine; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Chlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Chlorpheniramine; Ibuprofen; Pseudoephedrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Chlorpheniramine; Phenylephrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants like phenylephrine; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Chlorpheniramine; Pseudoephedrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Cholestyramine: (Moderate) Cholestyramine has been shown to decrease the absorption of acetaminophen by roughly 60%. Experts have recommended that cholestyramine not be given within 1 hour of acetaminophen if analgesic or antipyretic effect is to be achieved.
Choline Salicylate; Magnesium Salicylate: (Moderate) Prolonged concurrent use of acetaminophen and salicylates is not recommended. Although salicylates are rarely associated with nephrotoxicity, high-dose, chronic administration of salicylates combined other analgesics, including acetaminophen, significantly increases the risk of analgesic nephropathy, renal papillary necrosis, and end-stage renal disease. Additive hepatic toxicity may occur, especially in combined overdose situations. Do not exceed the recommended individual maximum doses when these agents are given concurrently for short-term therapy.
Cimetidine: (Minor) Inhibitors of CYP1A2, such as cimetidine, may inhibit the hepatic oxidative metabolism of caffeine. In patients who complain of caffeine-related side effects caffeine dosage or intake may need to be reduced.
Ciprofloxacin: (Moderate) Reduction or limitation of the caffeine dosage in medications and limitation of caffeine in beverages and food may be necessary during concurrent ciprofloxacin therapy. Ciprofloxacin can decrease the clearance of caffeine. Caffeine toxicity may occur and can manifest as nausea, vomiting, anxiety, tachycardia, or seizures. Ciprofloxacin is a CYP1A2 inhibitor and caffeine is a CYP1A2 substrate.
Clonazepam: (Minor) Patients taking benzodiazepines for insomnia should not use caffeine-containing products prior to going to bed as these products may antagonize the sedative effects of the benzodiazepine.
Clorazepate: (Minor) Patients taking benzodiazepines for insomnia should not use caffeine-containing products prior to going to bed as these products may antagonize the sedative effects of the benzodiazepine.
Clozapine: (Major) Caffeine may inhibit clozapine metabolism via CYP1A2. Clozapine clearance has been decreased by roughly 14 percent during coadministration of caffeine, and a documented increase in clozapine serum concentrations has occurred in selected patients. In addition, a single case report associates the appearance of psychiatric symptoms with caffeine ingestion in one patient taking clozapine. Until more data are available, caffeine consumption should be minimized during clozapine treatment.
Codeine; Guaifenesin; Pseudoephedrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Codeine; Phenylephrine; Promethazine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants like phenylephrine; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Dapsone: (Moderate) Coadministration of dapsone with acetaminophen may increase the risk of developing methemoglobinemia. Advise patients to discontinue treatment and seek immediate medical attention with any signs or symptoms of methemoglobinemia.
Darifenacin: (Minor) Consuming > 400 mg/day caffeine has been associated with the development of urinary incontinence. Caffeine may aggravate bladder symptoms, increase urination, and counteract the effectiveness of darifenacin to some degree. Patients may wish to limit their intake of caffeinated drugs, dietary supplements (e.g., guarana), or beverages (e.g., green tea, other teas, coffee, colas).
Desloratadine; Pseudoephedrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Desogestrel; Ethinyl Estradiol: (Moderate) Monitor for estrogen-related adverse effects during concomitant acetaminophen and ethinyl estradiol use. Acetaminophen may increase plasma ethinyl estradiol concentrations, possibly by inhibition of conjugation. (Minor) Serum concentrations of caffeine may be increased during concurrent administration with ethinyl estradiol. Patients may desire to limit products that contain high amounts of caffeine to minimize caffeine-related side effects such as nausea or tremors.
Dexbrompheniramine; Pseudoephedrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Dexchlorpheniramine; Dextromethorphan; Pseudoephedrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Dexmethylphenidate: (Moderate) Caffeine is a CNS stimulant and such actions are expected to be additive when coadministered with other CNS stimulants or psychostimulants. Avoid excessive caffeine intake during use of methylphenidate or its derivatives. Excessive caffeine ingestion (via medicines, foods like chocolate, dietary supplements, or beverages including coffee, green tea, other teas, colas) may contribute to side effects like nervousness, irritability, nausea, insomnia, or tremor. Patients should avoid medications and dietary supplements which contain high amounts of caffeine.
Dextroamphetamine: (Moderate) Avoid excessive caffeine intake during use of the amphetamine salts. Caffeine is a CNS-stimulant and such actions are expected to be additive when coadministered with other CNS stimulants or psychostimulants. Excessive caffeine ingestion (via medicines, foods like chocolate, dietary supplements, or beverages including coffee, green tea, other teas, colas) may contribute to side effects like nervousness, irritability, nausea, insomnia, or tremor. Patients should avoid medications and dietary supplements which contain high amounts of caffeine.
Dextromethorphan; Bupropion: (Moderate) Bupropion is associated with a dose-related risk of seizures. Excessive use of psychostimulants, including caffeine, is associated with an increased seizure risk and may increase this risk during the concurrent use of bupropion. Carefully consider a patient's caffeine intake from all sources, including medicines. Monitor for irritability, tremor, increased blood pressure, insomnia and seizures. Many non-prescription medicines and weight loss aids may contain caffeine and patients should read labels carefully. Examples of foods and beverages containing caffeine include coffee, teas, colas, energy drinks, chocolate, and some herbal or dietary supplements. Patients should be advised to limit excessive caffeine intake during bupropion therapy.
Dextromethorphan; Diphenhydramine; Phenylephrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants like phenylephrine; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Dextromethorphan; Guaifenesin; Phenylephrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants like phenylephrine; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Dextromethorphan; Guaifenesin; Pseudoephedrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Diazepam: (Minor) Patients taking benzodiazepines for insomnia should not use caffeine-containing products prior to going to bed as these products may antagonize the sedative effects of the benzodiazepine.
Diethylpropion: (Moderate) Caffeine is a CNS-stimulant and such actions are expected to be additive when coadministered with other CNS stimulants or psychostimulants.
Diflunisal: (Moderate) Acetaminophen plasma concentrations can increase by approximately 50% following administration of diflunisal. Acetaminophen has no effect on diflunisal concentrations. Acetaminophen in high doses has been associated with severe hepatotoxic reactions; therefore, caution should be exercised when using these agents concomitantly.
Diphenhydramine; Phenylephrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants like phenylephrine; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Dipyridamole: (Major) Methylxanthines, through antagonism of adenosine and thus pharmacologic-induced coronary vasodilation, have been associated with false-negative results during dipyridamole-thallium 201 stress testing. It is recommended that methylxanthines (caffeine, caffeinated beverages and foods, theophylline, etc.) be discontinued for at least 24 hours prior to stress testing. An interaction is not expected when methylxanthines are used concomitantly with chronic dipyridamole therapy.
Disulfiram: (Moderate) Disulfiram has been shown to inhibit caffeine elimination. Caffeine elimination decreased by 30 percent in those patients that were not recovering alcoholics and by 24 percent in those patients that were recovering alcoholics. During disulfiram therapy, patients may need to limit their caffeine intake if nausea, nervousness, tremor, restlessness, palpitations, or insomnia complaints occur. Adverse events were not noted during this pharmacokinetic study, however, the decrease in caffeine clearance could be significant in some patients, including some patients with cardiovascular disease.
Dobutamine: (Moderate) Caffeine is a CNS-stimulant and such actions are expected to be additive when coadministered with other CNS stimulants or psychostimulants.
Dopamine: (Moderate) Caffeine is a CNS-stimulant and such actions are expected to be additive when coadministered with other CNS stimulants or psychostimulants.
Doxapram: (Moderate) Caffeine is a CNS-stimulant and such actions are expected to be additive when coadministered with other CNS stimulants or psychostimulants, like doxapram. CNS stimulants and sympathomimetics are associated with adverse effects such as nervousness, irritability, insomnia, and/or cardiac arrhythmias, and the concomitant use of these drugs increases the risk of developing such adverse reactions. Coadminsitration should be avoided or used cautiously.
Drospirenone; Ethinyl Estradiol: (Moderate) Monitor for estrogen-related adverse effects during concomitant acetaminophen and ethinyl estradiol use. Acetaminophen may increase plasma ethinyl estradiol concentrations, possibly by inhibition of conjugation. (Minor) Serum concentrations of caffeine may be increased during concurrent administration with ethinyl estradiol. Patients may desire to limit products that contain high amounts of caffeine to minimize caffeine-related side effects such as nausea or tremors.
Drospirenone; Ethinyl Estradiol; Levomefolate: (Moderate) Monitor for estrogen-related adverse effects during concomitant acetaminophen and ethinyl estradiol use. Acetaminophen may increase plasma ethinyl estradiol concentrations, possibly by inhibition of conjugation. (Minor) Serum concentrations of caffeine may be increased during concurrent administration with ethinyl estradiol. Patients may desire to limit products that contain high amounts of caffeine to minimize caffeine-related side effects such as nausea or tremors.
Echinacea: (Moderate) Echinacea may inhibit the metabolism of caffeine. Echinacea reduces the oral clearance of caffeine by 27 percent and increases the mean AUC by 129 percent. Monitor patients for signs of increased caffeine serum concentrations if these drugs are coadministered until more data are available.
Efavirenz: (Minor) Drugs that induce the hepatic isoenzymes CYP2E1 and CYP1A2, such as efavirenz, may potentially increase the risk for acetaminophen-induced hepatotoxicity via generation of a greater percentage of acetaminophen's hepatotoxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Efavirenz; Emtricitabine; Tenofovir Disoproxil Fumarate: (Minor) Drugs that induce the hepatic isoenzymes CYP2E1 and CYP1A2, such as efavirenz, may potentially increase the risk for acetaminophen-induced hepatotoxicity via generation of a greater percentage of acetaminophen's hepatotoxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Efavirenz; Lamivudine; Tenofovir Disoproxil Fumarate: (Minor) Drugs that induce the hepatic isoenzymes CYP2E1 and CYP1A2, such as efavirenz, may potentially increase the risk for acetaminophen-induced hepatotoxicity via generation of a greater percentage of acetaminophen's hepatotoxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Eltrombopag: (Moderate) Eltrombopag is a UDP-glucuronyltransferase inhibitor. Acetaminophen is a substrate of UDP-glucuronyltransferases. The significance or effect of this interaction is not known; however, elevated concentrations of acetaminophen are possible. Monitor patients for adverse reactions if these drugs are coadministered.
Enasidenib: (Moderate) Monitor for an increase in caffeine-related adverse reactions, including nervousness, irritability, insomnia, tachycardia, or tremor, if concomitant use of enasidenib is necessary; lower caffeine doses may be necessary. Concomitant use may increase caffeine exposure; caffeine is a CYP1A2 substrate and enasidenib is a CYP1A2 inhibitor.
Ephedrine: (Moderate) Caffeine is a CNS-stimulant and such actions are expected to be additive when coadministered with other CNS stimulants or psychostimulants like ephedrine. Adverse effects such as nervousness, irritability, insomnia, and/or cardiac arrhythmias are also possible when excessive dosages of caffeine are taken concurrently with ephedrine. Patients may also need to limit their intake of caffeine-containing beverages or foods (e.g., coffee, green tea, other teas, guarana, colas, or chocolate) to avoid caffeine-like side effects.
Ephedrine; Guaifenesin: (Moderate) Caffeine is a CNS-stimulant and such actions are expected to be additive when coadministered with other CNS stimulants or psychostimulants like ephedrine. Adverse effects such as nervousness, irritability, insomnia, and/or cardiac arrhythmias are also possible when excessive dosages of caffeine are taken concurrently with ephedrine. Patients may also need to limit their intake of caffeine-containing beverages or foods (e.g., coffee, green tea, other teas, guarana, colas, or chocolate) to avoid caffeine-like side effects.
Epinephrine: (Moderate) Caffeine is a CNS-stimulant and such actions are expected to be additive when coadministered with other CNS stimulants or psychostimulants.
Erythromycin: (Moderate) Inhibitors of the hepatic CYP4501A2, such as erythromycin, may inhibit the hepatic oxidative metabolism of caffeine. No specific management is recommended except in patients who complain of caffeine related side effects. In such patients, the dosage of caffeine containing medications or the ingestion of caffeine containing products may need to be reduced.
Esketamine: (Major) Closely monitor blood pressure during concomitant use of esketamine and caffeine. Coadministration of psychostimulants, such as caffeine, with esketamine may increase blood pressure.
Estazolam: (Minor) Patients taking benzodiazepines for insomnia should not use caffeine-containing products prior to going to bed as these products may antagonize the sedative effects of the benzodiazepine.
Eszopiclone: (Minor) Patients taking eszopiclone for sleep should avoid caffeine-containing medications, dietary supplements, foods, and beverages close to bedtime, as well as excessive total daily caffeine intake, as part of proper sleep hygiene, since caffeine intake can interfere with proper sleep. Limit use of caffeine-containing products including medications, dietary supplements (e.g., guarana), and beverages (e.g., coffee, green tea, other teas, or colas).
Ethanol: (Major) The risk of developing hepatotoxicity from acetaminophen appears to be increased in patients who regularly consume alcohol. Patients who drink more than 3 alcohol-containing drinks a day and take acetaminophen are at increased risk of developing hepatotoxicity. Acute or chronic alcohol use increases acetaminophen-induced hepatotoxicity by inducing CYP2E1 leading to increased formation of the hepatotoxic metabolite of acetaminophen. Also, chronic alcohol use can deplete liver glutathione stores. Administration of acetaminophen should be limited or avoided altogether in patients with alcoholism or patients who consume alcohol regularly.
Ethinyl Estradiol; Norelgestromin: (Moderate) Monitor for estrogen-related adverse effects during concomitant acetaminophen and ethinyl estradiol use. Acetaminophen may increase plasma ethinyl estradiol concentrations, possibly by inhibition of conjugation. (Minor) Serum concentrations of caffeine may be increased during concurrent administration with ethinyl estradiol. Patients may desire to limit products that contain high amounts of caffeine to minimize caffeine-related side effects such as nausea or tremors.
Ethinyl Estradiol; Norethindrone Acetate: (Moderate) Monitor for estrogen-related adverse effects during concomitant acetaminophen and ethinyl estradiol use. Acetaminophen may increase plasma ethinyl estradiol concentrations, possibly by inhibition of conjugation. (Minor) Serum concentrations of caffeine may be increased during concurrent administration with ethinyl estradiol. Patients may desire to limit products that contain high amounts of caffeine to minimize caffeine-related side effects such as nausea or tremors.
Ethinyl Estradiol; Norgestrel: (Moderate) Monitor for estrogen-related adverse effects during concomitant acetaminophen and ethinyl estradiol use. Acetaminophen may increase plasma ethinyl estradiol concentrations, possibly by inhibition of conjugation. (Minor) Serum concentrations of caffeine may be increased during concurrent administration with ethinyl estradiol. Patients may desire to limit products that contain high amounts of caffeine to minimize caffeine-related side effects such as nausea or tremors.
Ethiodized Oil: (Major) Use of medications that lower the seizure threshold should be carefully evaluated when considering intrathecal radiopaque contrast agents. Caffeine and caffeine containing products should be discontinued at least 48 hours before myelography and should not be resumed for at least 24 hours post-procedure.
Ethotoin: (Moderate) Higher caffeine doses may be needed after hydantoin administration; hydantoins increase caffeine elimination. (Minor) Hydantoin anticonvulsants induce hepatic microsomal enzymes and may increase the metabolism of other drugs, leading to reduced efficacy of medications like acetaminophen. In addition, the risk of hepatotoxicity from acetaminophen may be increased with the chronic dosing of acetaminophen along with phenytoin. Adhere to recommended acetaminophen dosage limits. Acetaminophen-related hepatotoxicity has occurred clinically with the concurrent use of acetaminophen 1300 mg to 6200 mg daily and phenytoin. Acetaminophen cessation led to serum transaminase normalization within 2 weeks.
Ethynodiol Diacetate; Ethinyl Estradiol: (Moderate) Monitor for estrogen-related adverse effects during concomitant acetaminophen and ethinyl estradiol use. Acetaminophen may increase plasma ethinyl estradiol concentrations, possibly by inhibition of conjugation. (Minor) Serum concentrations of caffeine may be increased during concurrent administration with ethinyl estradiol. Patients may desire to limit products that contain high amounts of caffeine to minimize caffeine-related side effects such as nausea or tremors.
Etonogestrel; Ethinyl Estradiol: (Moderate) Monitor for estrogen-related adverse effects during concomitant acetaminophen and ethinyl estradiol use. Acetaminophen may increase plasma ethinyl estradiol concentrations, possibly by inhibition of conjugation. (Minor) Serum concentrations of caffeine may be increased during concurrent administration with ethinyl estradiol. Patients may desire to limit products that contain high amounts of caffeine to minimize caffeine-related side effects such as nausea or tremors.
Exenatide: (Minor) Although an interaction is possible, these drugs may be used together. To avoid potential pharmacokinetic interactions that might alter effectiveness of acetaminophen, it may be advisable for patients to take acetaminophen at least 1 hour prior to an exenatide injection. When 1,000 mg acetaminophen elixir was given with 10 mcg exenatide (at 0 hours) and at 1, 2 and 4 hours after exenatide injection, acetaminophen AUCs were decreased by 21%, 23%, 24%, and 14%, respectively; Cmax was decreased by 37%, 56%, 54%, and 41%, respectively. Additionally, acetaminophen Tmax was delayed from 0.6 hours in the control period to 0.9, 4.2, 3.3, and 1.6 hours, respectively. Acetaminophen AUC, Cmax, and Tmax were not significantly changed when acetaminophen was given 1 h before exenatide injection. The mechanism of this interaction is not available (although it may be due to delayed gastric emptying from exenatide use) and the clinical impact has not been assessed.
Fesoterodine: (Minor) Beverages containing caffeine or ethanol may aggravate bladder symptoms and counteract the effectiveness of fesoterodine to some degree. Patients may wish to limit their intake of caffeinated drugs, dietary supplements (e.g., guarana), or beverages (e.g., green tea, other teas, coffee, colas) and alcoholic beverages.
Fexinidazole: (Moderate) Monitor for an increase in caffeine-related adverse reactions, including nervousness, irritability, insomnia, tachycardia, or tremor, if concomitant use of fexinidazole is necessary; lower caffeine doses may be necessary. Concomitant use may increase caffeine exposure; caffeine is a CYP1A2 substrate and fexinidazole is a CYP1A2 inhibitor.
Fexofenadine; Pseudoephedrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Fluconazole: (Moderate) Fluconazole has been shown to inhibit the clearance of caffeine by 25 percent. The clinical significance of these interactions has not been determined.
Flurazepam: (Minor) Patients taking benzodiazepines for insomnia should not use caffeine-containing products prior to going to bed as these products may antagonize the sedative effects of the benzodiazepine.
Fluticasone; Salmeterol: (Moderate) Caffeine may enhance the cardiac inotropic effects of beta-agonists.
Fluticasone; Umeclidinium; Vilanterol: (Moderate) Caffeine may enhance the cardiac inotropic effects of beta-agonists.
Fluticasone; Vilanterol: (Moderate) Caffeine may enhance the cardiac inotropic effects of beta-agonists.
Fluvoxamine: (Moderate) Strong inhibitors of CYP1A2, such as fluvoxamine, may inhibit the metabolism of caffeine. No specific management is recommended except in patients with caffeine-related side effects after initiating fluvoxamine. In such patients, the dosage of caffeine containing medications or the ingestion of caffeine containing products may need to be reduced.
Formoterol: (Moderate) Caffeine may enhance the cardiac inotropic effects of beta-agonists.
Formoterol; Mometasone: (Moderate) Caffeine may enhance the cardiac inotropic effects of beta-agonists.
Fosphenytoin: (Moderate) Higher caffeine doses may be needed after hydantoin administration; hydantoins increase caffeine elimination. (Minor) Hydantoin anticonvulsants induce hepatic microsomal enzymes and may increase the metabolism of other drugs, leading to reduced efficacy of medications like acetaminophen. In addition, the risk of hepatotoxicity from acetaminophen may be increased with the chronic dosing of acetaminophen along with phenytoin. Adhere to recommended acetaminophen dosage limits. Acetaminophen-related hepatotoxicity has occurred clinically with the concurrent use of acetaminophen 1300 mg to 6200 mg daily and phenytoin. Acetaminophen cessation led to serum transaminase normalization within 2 weeks.
Givosiran: (Major) Avoid concomitant use of givosiran and caffeine due to the risk of increased caffeine-related adverse reactions. If use is necessary, consider decreasing the caffeine dose. Caffeine is a sensitive CYP1A2 substrate. Givosiran may moderately reduce hepatic CYP1A2 enzyme activity because of its pharmacological effects on the hepatic heme biosynthesis pathway.
Glycopyrrolate; Formoterol: (Moderate) Caffeine may enhance the cardiac inotropic effects of beta-agonists.
Grapefruit juice: (Minor) Data are limited and conflicting as to whether grapefruit juice significantly alters the serum concentrations and/or AUC of caffeine. Caffeine is primarily a CYP1A2 substrate, and grapefruit juice appears to have but a small effect on this enzyme in vivo. One report suggests that grapefruit juice decreases caffeine elimination by inhibition of flavin-containing monooxygenase, a P450 independent system. This interaction might increase caffeine levels and mildly potentiate the clinical effects and common side effects of caffeine. If side effects appear, patients may need to limit either caffeine or grapefruit juice intake.
Green Tea: (Moderate) Many green tea products contain caffeine. Due to the risk for adverse effects, avoid the concurrent administration of caffeine and green tea products that contain caffeine when possible. Concurrent administration can produce excessive caffeine-related adverse events such as nausea, irritability, nervousness, and insomnia.
Guaifenesin; Phenylephrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants like phenylephrine; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Guaifenesin; Pseudoephedrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Hydantoins: (Moderate) Higher caffeine doses may be needed after hydantoin administration; hydantoins increase caffeine elimination. (Minor) Hydantoin anticonvulsants induce hepatic microsomal enzymes and may increase the metabolism of other drugs, leading to reduced efficacy of medications like acetaminophen. In addition, the risk of hepatotoxicity from acetaminophen may be increased with the chronic dosing of acetaminophen along with phenytoin. Adhere to recommended acetaminophen dosage limits. Acetaminophen-related hepatotoxicity has occurred clinically with the concurrent use of acetaminophen 1300 mg to 6200 mg daily and phenytoin. Acetaminophen cessation led to serum transaminase normalization within 2 weeks.
Ibuprofen; Pseudoephedrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Imatinib: (Major) Imatinib, STI-571 may affect the metabolism of acetaminophen. In vitro, imatinib was found to inhibit acetaminophen O-glucuronidation at therapeutic levels. Therefore, systemic exposure to acetaminophen is expected to be increased with coadministration of imatinib. Chronic acetaminophen therapy should be avoided in patients receiving imatinib.
Indacaterol; Glycopyrrolate: (Moderate) Caffeine may enhance the cardiac inotropic effects of beta-agonists.
Insulin Glargine; Lixisenatide: (Minor) When 1,000 mg acetaminophen was given 1 or 4 hours after 10 mcg lixisenatide, the AUC was not significantly changed, but the acetaminophen Cmax was decreased by 29% and 31%, respectively and median Tmax was delayed by 2 and 1.75 hours, respectively. Acetaminophen AUC, Cmax, and Tmax were not significantly changed when acetaminophen was given 1 h before lixisenatide injection. The mechanism of this interaction is not available (although it may be due to delayed gastric emptying) and the clinical impact has not been assessed. To avoid potential pharmacokinetic interactions that might alter effectiveness of acetaminophen, it may be advisable for patients to take acetaminophen at least one hour prior to lixisenatide subcutaneous injection.
Iodixanol: (Major) Use of medications that lower the seizure threshold should be carefully evaluated when considering intrathecal radiopaque contrast agents. Caffeine and caffeine containing products should be discontinued at least 48 hours before myelography and should not be resumed for at least 24 hours post-procedure.
Iohexol: (Major) Use of medications that lower the seizure threshold should be carefully evaluated when considering intrathecal radiopaque contrast agents. Caffeine and caffeine containing products should be discontinued at least 48 hours before myelography and should not be resumed for at least 24 hours post-procedure.
Iomeprol: (Major) Use of medications that lower the seizure threshold should be carefully evaluated when considering intrathecal radiopaque contrast agents. Caffeine and caffeine containing products should be discontinued at least 48 hours before myelography and should not be resumed for at least 24 hours post-procedure.
Iopamidol: (Major) Use of medications that lower the seizure threshold should be carefully evaluated when considering intrathecal radiopaque contrast agents. Caffeine and caffeine containing products should be discontinued at least 48 hours before myelography and should not be resumed for at least 24 hours post-procedure.
Iopromide: (Major) Use of medications that lower the seizure threshold should be carefully evaluated when considering intrathecal radiopaque contrast agents. Caffeine and caffeine containing products should be discontinued at least 48 hours before myelography and should not be resumed for at least 24 hours post-procedure.
Ioversol: (Major) Use of medications that lower the seizure threshold should be carefully evaluated when considering intrathecal radiopaque contrast agents. Caffeine and caffeine containing products should be discontinued at least 48 hours before myelography and should not be resumed for at least 24 hours post-procedure.
Ipratropium; Albuterol: (Moderate) Caffeine may enhance the cardiac inotropic effects of beta-agonists.
Isavuconazonium: (Moderate) Concomitant use of isavuconazonium with acetaminophen may result in increased serum concentrations of acetaminophen. Acetaminophen is a substrate of the hepatic isoenzyme CYP3A4; isavuconazole, the active moiety of isavuconazonium, is a moderate inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are used together.
Isocarboxazid: (Major) Excessive use of caffeine in any form should be avoided in patients receiving Monoamine oxidase inhibitors (MAOIs). Limit caffeine intake during MAOI use and for 1 to 2 weeks after discontinuation of any MAOI. The use of non-prescription medicines or dietary supplements containing caffeine should be avoided. Patients should try to avoid or limit the intake of all items containing caffeine such as tea, coffee, chocolate, and cola. Cardiac arrhythmias or severe hypertension may occur because of the potentiation of caffeine's sympathomimetic effects by MAOIs if caffeine intake is excessive.
Isoniazid, INH: (Major) Agents which induce the hepatic isoenzyme CYP2E1, such as isoniazid, may potentially increase the risk for acetaminophen-induced hepatotoxicity via generation of a greater percentage of acetaminophen's hepatotoxic metabolites. The combination of isoniazid and acetaminophen has caused severe hepatotoxicity in at least one patient; studies in rats have demonstrated that pre-treatment with isoniazid potentiates acetaminophen hepatotoxicity. (Moderate) Although isoniazid does not inhibit mitochondrial MAO, it does appear to inhibit plasma MAO. Dangerous cardiac arrhythmias or severe hypertension can occur because of the potentiation of caffeine's sympathomimetic effects by MAOIs. Caffeine use should be minimized or avoided during and for 1 to 2 weeks after discontinuation of any MAOI.
Isoniazid, INH; Pyrazinamide, PZA; Rifampin: (Major) Agents which induce the hepatic isoenzyme CYP2E1, such as isoniazid, may potentially increase the risk for acetaminophen-induced hepatotoxicity via generation of a greater percentage of acetaminophen's hepatotoxic metabolites. The combination of isoniazid and acetaminophen has caused severe hepatotoxicity in at least one patient; studies in rats have demonstrated that pre-treatment with isoniazid potentiates acetaminophen hepatotoxicity. (Moderate) Although isoniazid does not inhibit mitochondrial MAO, it does appear to inhibit plasma MAO. Dangerous cardiac arrhythmias or severe hypertension can occur because of the potentiation of caffeine's sympathomimetic effects by MAOIs. Caffeine use should be minimized or avoided during and for 1 to 2 weeks after discontinuation of any MAOI. (Moderate) Concomitant use of acetaminophen with rifampin may increase the known risk of hepatotoxicity in relation to each drug. Severe hepatic dysfunction including fatalities were reported in patients taking rifampin with other hepatotoxic agents. (Minor) Rifampin is a potent inducer of the cytochrome P450 hepatic enzyme system and can reduce the plasma concentrations and possibly the efficacy of caffeine, including caffeine found in green tea products.
Isoniazid, INH; Rifampin: (Major) Agents which induce the hepatic isoenzyme CYP2E1, such as isoniazid, may potentially increase the risk for acetaminophen-induced hepatotoxicity via generation of a greater percentage of acetaminophen's hepatotoxic metabolites. The combination of isoniazid and acetaminophen has caused severe hepatotoxicity in at least one patient; studies in rats have demonstrated that pre-treatment with isoniazid potentiates acetaminophen hepatotoxicity. (Moderate) Although isoniazid does not inhibit mitochondrial MAO, it does appear to inhibit plasma MAO. Dangerous cardiac arrhythmias or severe hypertension can occur because of the potentiation of caffeine's sympathomimetic effects by MAOIs. Caffeine use should be minimized or avoided during and for 1 to 2 weeks after discontinuation of any MAOI. (Moderate) Concomitant use of acetaminophen with rifampin may increase the known risk of hepatotoxicity in relation to each drug. Severe hepatic dysfunction including fatalities were reported in patients taking rifampin with other hepatotoxic agents. (Minor) Rifampin is a potent inducer of the cytochrome P450 hepatic enzyme system and can reduce the plasma concentrations and possibly the efficacy of caffeine, including caffeine found in green tea products.
Isoproterenol: (Moderate) Caffeine is a CNS-stimulant and such actions are expected to be additive when coadministered with other CNS stimulants or psychostimulants.
Isosulfan Blue: (Major) Use of medications that lower the seizure threshold should be carefully evaluated when considering intrathecal radiopaque contrast agents. Caffeine and caffeine containing products should be discontinued at least 48 hours before myelography and should not be resumed for at least 24 hours post-procedure.
Ketoconazole: (Moderate) Ketoconazole has been shown to inhibit the clearance of caffeine by 11 percent. The clinical significance of these interactions has not been determined.
Ketoprofen: (Minor) Caffeine administered concurrently with ketoprofen reduced the urine volume in 4 healthy volunteers. The clinical significance of the interaction in preterm neonates is not known.
Lamivudine, 3TC; Zidovudine, ZDV: (Minor) Both acetaminophen and zidovudine, ZDV undergo glucuronidation. Competition for the metabolic pathway is thought to have caused a case of acetaminophen-related hepatotoxicity. This interaction may be more clinically significant in patients with depleted glutathione stores, such as patients with acquired immunodeficiency syndrome, poor nutrition, or alcoholism.
Lamotrigine: (Moderate) Monitor patients for possible loss of lamotrigine efficacy and seizure activity during coadministration with acetaminophen. Acetaminophen may induce glucuronidation pathways involved in lamotrigine metabolism. During a study among 12 healthy volunteers, concomitant administration of acetaminophen 4 g/day with lamotrigine at steady-state increased the formation clearance of lamotrigine glucuronide conjugates by 45%, decreased lamotrigine AUC by 20%, and reduced lamotrigine trough concentrations by 25%.
Leniolisib: (Moderate) Monitor for an increase in caffeine-related adverse reactions, including nervousness, irritability, insomnia, tachycardia, or tremor, if concomitant use of leniolisib is necessary; lower caffeine doses may be necessary. Concomitant use may increase caffeine exposure; caffeine is a CYP1A2 substrate and leniolisib is a CYP1A2 inhibitor.
Levalbuterol: (Moderate) Caffeine may enhance the cardiac inotropic effects of beta-agonists.
Levoketoconazole: (Moderate) Ketoconazole has been shown to inhibit the clearance of caffeine by 11 percent. The clinical significance of these interactions has not been determined.
Levonorgestrel; Ethinyl Estradiol: (Moderate) Monitor for estrogen-related adverse effects during concomitant acetaminophen and ethinyl estradiol use. Acetaminophen may increase plasma ethinyl estradiol concentrations, possibly by inhibition of conjugation. (Minor) Serum concentrations of caffeine may be increased during concurrent administration with ethinyl estradiol. Patients may desire to limit products that contain high amounts of caffeine to minimize caffeine-related side effects such as nausea or tremors.
Levonorgestrel; Ethinyl Estradiol; Ferrous Bisglycinate: (Moderate) Monitor for estrogen-related adverse effects during concomitant acetaminophen and ethinyl estradiol use. Acetaminophen may increase plasma ethinyl estradiol concentrations, possibly by inhibition of conjugation. (Minor) Serum concentrations of caffeine may be increased during concurrent administration with ethinyl estradiol. Patients may desire to limit products that contain high amounts of caffeine to minimize caffeine-related side effects such as nausea or tremors.
Levonorgestrel; Ethinyl Estradiol; Ferrous Fumarate: (Moderate) Monitor for estrogen-related adverse effects during concomitant acetaminophen and ethinyl estradiol use. Acetaminophen may increase plasma ethinyl estradiol concentrations, possibly by inhibition of conjugation. (Minor) Serum concentrations of caffeine may be increased during concurrent administration with ethinyl estradiol. Patients may desire to limit products that contain high amounts of caffeine to minimize caffeine-related side effects such as nausea or tremors.
Lidocaine: (Moderate) Coadministration of lidocaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue lidocaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Lidocaine; Epinephrine: (Moderate) Caffeine is a CNS-stimulant and such actions are expected to be additive when coadministered with other CNS stimulants or psychostimulants. (Moderate) Coadministration of lidocaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue lidocaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Lidocaine; Prilocaine: (Moderate) Coadministration of lidocaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue lidocaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen. (Moderate) Coadministration of prilocaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue prilocaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Linezolid: (Moderate) Caffeine use should be minimized or avoided during and for 1 to 2 weeks after discontinuation of linezolid. Linezolid is an antibiotic that is also a weak, reversible nonselective inhibitor of monoamine oxidase (MAO). Dangerous cardiac arrhythmias or severe hypertension can occur because of the potentiation of caffeine's sympathomimetic effects by MAOIs.
Lisdexamfetamine: (Moderate) Avoid excessive caffeine intake during use of lisdexamfetamine. Caffeine is a CNS-stimulant and such actions are expected to be additive when coadministered with other CNS stimulants or psychostimulants. Excessive caffeine ingestion (via medicines, foods like chocolate, dietary supplements, or beverages including coffee, green tea, other teas, colas) may contribute to side effects like nervousness, irritability, nausea, insomnia, or tremor. Patients should avoid medications and dietary supplements which contain high amounts of caffeine.
Lithium: (Major) Caffeine appears to reduce serum lithium concentrations. Adverse reactions to lithium have also been noted to increase simultaneously with a reduction in caffeine intake. Patients taking lithium should be counseled regarding their intake of caffeine.
Lixisenatide: (Minor) When 1,000 mg acetaminophen was given 1 or 4 hours after 10 mcg lixisenatide, the AUC was not significantly changed, but the acetaminophen Cmax was decreased by 29% and 31%, respectively and median Tmax was delayed by 2 and 1.75 hours, respectively. Acetaminophen AUC, Cmax, and Tmax were not significantly changed when acetaminophen was given 1 h before lixisenatide injection. The mechanism of this interaction is not available (although it may be due to delayed gastric emptying) and the clinical impact has not been assessed. To avoid potential pharmacokinetic interactions that might alter effectiveness of acetaminophen, it may be advisable for patients to take acetaminophen at least one hour prior to lixisenatide subcutaneous injection.
Lomitapide: (Moderate) Caution should be exercised when lomitapide is used with other medications known to have potential for hepatotoxicity, such as acetaminophen (> 4 g/day PO for >= 3 days/week). The effect of concomitant administration of lomitapide with other hepatotoxic medications is unknown. More frequent monitoring of liver-related tests may be warranted.
Lopinavir; Ritonavir: (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together.
Loratadine; Pseudoephedrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Lorazepam: (Minor) Patients taking benzodiazepines for insomnia should not use caffeine-containing products prior to going to bed as these products may antagonize the sedative effects of the benzodiazepine.
Magnesium Hydroxide: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
Magnesium Salts: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
Melatonin: (Minor) Caffeine is a central nervous system (CNS) stimulant. Patients taking melatonin for sleep should avoid caffeine-containing medications, dietary supplements, foods, and beverages close to bedtime, as well as excessive total daily caffeine intake, as part of proper sleep hygiene, since caffeine intake can interfere with proper sleep.
Mepivacaine: (Moderate) Coadministration of mepivacaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue mepivacaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Metaproterenol: (Moderate) Caffeine may enhance the cardiac inotropic effects of beta-agonists.
Methamphetamine: (Moderate) Caffeine is a CNS-stimulant and such actions are expected to be additive when coadministered with other CNS stimulants or psychostimulants. Avoid excessive caffeine intake during use of methamphetamine. Excessive caffeine ingestion (via medicines, foods like chocolate, dietary supplements, or beverages including coffee, green tea, other teas, colas) may contribute to side effects like nervousness, irritability, nausea, insomnia, or tremor. Patients should avoid medications and dietary supplements which contain high amounts of caffeine.
Methohexital: (Moderate) Caffeine has been reported to increase the metabolism of barbiturates, and barbiturates increase caffeine elimination. Higher caffeine doses may be needed after barbiturate administration. (Minor) Chronic therapy with barbiturates can increase the metabolism and decrease the effectiveness of acetaminophen. During acute overdoses, barbiturates can enhance the formation of toxic acetaminophen metabolites.
Methylphenidate Derivatives: (Moderate) Caffeine is a CNS stimulant and such actions are expected to be additive when coadministered with other CNS stimulants or psychostimulants. Avoid excessive caffeine intake during use of methylphenidate or its derivatives. Excessive caffeine ingestion (via medicines, foods like chocolate, dietary supplements, or beverages including coffee, green tea, other teas, colas) may contribute to side effects like nervousness, irritability, nausea, insomnia, or tremor. Patients should avoid medications and dietary supplements which contain high amounts of caffeine.
Methylphenidate: (Moderate) Caffeine is a CNS stimulant and such actions are expected to be additive when coadministered with other CNS stimulants or psychostimulants. Avoid excessive caffeine intake during use of methylphenidate or its derivatives. Excessive caffeine ingestion (via medicines, foods like chocolate, dietary supplements, or beverages including coffee, green tea, other teas, colas) may contribute to side effects like nervousness, irritability, nausea, insomnia, or tremor. Patients should avoid medications and dietary supplements which contain high amounts of caffeine.
Metyrapone: (Major) Coadministration of metyrapone and acetaminophen may result in acetaminophen toxicity. Acetaminophen glucuronidation is inhibited by metyrapone. It may be advisable for patients to avoid acetaminophen while taking metyrapone.
Mexiletine: (Moderate) Mexiletine is an inhibitor of CYP1A2 isoenzymes, and may reduce CYP1A2-mediated caffeine metabolism. Mexiletine has been shown to increase caffeine concentrations by as much as 23 percent after a single 200 mg dose of mexiletine (nonsignificant increase, p<0.1). Another study has reported that the elimination of caffeine is decreased by 50 percent. While the clinical significance of this interaction is not known, elevated plasma caffeine levels may be of concern in patients with arrhythmias. Patients with cardiac arrhythmias on mexiletine should be cautioned to limit their intake of caffeine.
Midazolam: (Minor) Patients taking benzodiazepines for insomnia should not use caffeine-containing products prior to going to bed as these products may antagonize the sedative effects of the benzodiazepine.
Midodrine: (Moderate) Caffeine is a CNS-stimulant and such actions are expected to be additive when coadministered with other CNS stimulants or psychostimulants.
Migalastat: (Moderate) Separate the administration of oral caffeine and migalastat by at least 2 hours if concomitant use is necessary. Simultaneous coadministration may decrease migalastat exposure and efficacy. Coadministration of 190 mg caffeine reduced the mean migalastat AUC by 55%.
Mitotane: (Minor) Use caution if mitotane and acetaminophen are used concomitantly, and monitor for decreased efficacy of acetaminophen. Mitotane is a strong CYP3A4 inducer and acetaminophen is a minor (10% to 15%) CYP3A4 substrate; coadministration may result in decreased plasma concentrations of acetaminophen.
Modafinil: (Moderate) Caffeine is a CNS-stimulant and such actions are expected to be additive when coadministered with other CNS stimulants or psychostimulants. Caffeine should be used cautiously with modafinil. Excessive intake should be limited. Excessive intake may cause nervousness, irritability, insomnia or other side effects.
Monoamine oxidase inhibitors: (Major) Excessive use of caffeine in any form should be avoided in patients receiving Monoamine oxidase inhibitors (MAOIs). Limit caffeine intake during MAOI use and for 1 to 2 weeks after discontinuation of any MAOI. The use of non-prescription medicines or dietary supplements containing caffeine should be avoided. Patients should try to avoid or limit the intake of all items containing caffeine such as tea, coffee, chocolate, and cola. Cardiac arrhythmias or severe hypertension may occur because of the potentiation of caffeine's sympathomimetic effects by MAOIs if caffeine intake is excessive.
Naproxen; Pseudoephedrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Nirmatrelvir; Ritonavir: (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together.
Non-Ionic Contrast Media: (Major) Use of medications that lower the seizure threshold should be carefully evaluated when considering intrathecal radiopaque contrast agents. Caffeine and caffeine containing products should be discontinued at least 48 hours before myelography and should not be resumed for at least 24 hours post-procedure.
Norepinephrine: (Moderate) Caffeine is a CNS-stimulant and such actions are expected to be additive when coadministered with other CNS stimulants or psychostimulants.
Norethindrone Acetate; Ethinyl Estradiol; Ferrous fumarate: (Moderate) Monitor for estrogen-related adverse effects during concomitant acetaminophen and ethinyl estradiol use. Acetaminophen may increase plasma ethinyl estradiol concentrations, possibly by inhibition of conjugation. (Minor) Serum concentrations of caffeine may be increased during concurrent administration with ethinyl estradiol. Patients may desire to limit products that contain high amounts of caffeine to minimize caffeine-related side effects such as nausea or tremors.
Norethindrone; Ethinyl Estradiol: (Moderate) Monitor for estrogen-related adverse effects during concomitant acetaminophen and ethinyl estradiol use. Acetaminophen may increase plasma ethinyl estradiol concentrations, possibly by inhibition of conjugation. (Minor) Serum concentrations of caffeine may be increased during concurrent administration with ethinyl estradiol. Patients may desire to limit products that contain high amounts of caffeine to minimize caffeine-related side effects such as nausea or tremors.
Norethindrone; Ethinyl Estradiol; Ferrous fumarate: (Moderate) Monitor for estrogen-related adverse effects during concomitant acetaminophen and ethinyl estradiol use. Acetaminophen may increase plasma ethinyl estradiol concentrations, possibly by inhibition of conjugation. (Minor) Serum concentrations of caffeine may be increased during concurrent administration with ethinyl estradiol. Patients may desire to limit products that contain high amounts of caffeine to minimize caffeine-related side effects such as nausea or tremors.
Norgestimate; Ethinyl Estradiol: (Moderate) Monitor for estrogen-related adverse effects during concomitant acetaminophen and ethinyl estradiol use. Acetaminophen may increase plasma ethinyl estradiol concentrations, possibly by inhibition of conjugation. (Minor) Serum concentrations of caffeine may be increased during concurrent administration with ethinyl estradiol. Patients may desire to limit products that contain high amounts of caffeine to minimize caffeine-related side effects such as nausea or tremors.
Obeticholic Acid: (Moderate) Monitor for an increase in caffeine-related adverse reactions, including nervousness, irritability, insomnia, tachycardia, or tremor, if concomitant use of obeticholic acid is necessary; lower caffeine doses may be necessary. Concomitant use has been observed to increase caffeine overall exposure by 42%; caffeine is a CYP1A2 substrate and obeticholic acid is a CYP1A2 inhibitor.
Olodaterol: (Moderate) Caffeine may enhance the cardiac inotropic effects of beta-agonists.
Omeprazole; Amoxicillin; Rifabutin: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Omeprazole; Sodium Bicarbonate: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
Oxazepam: (Minor) Patients taking benzodiazepines for insomnia should not use caffeine-containing products prior to going to bed as these products may antagonize the sedative effects of the benzodiazepine.
Oxybutynin: (Minor) Consuming greater than 400 mg/day caffeine has been associated with the development of urinary incontinence. Caffeine may aggravate bladder symptoms, increase urine output, and counteract the effectiveness of drugs used to treat overactive bladder such as oxybutynin. Patients may wish to limit their intake of caffeinated drugs, dietary supplements (e.g., guarana), or beverages (e.g., green tea, other teas, coffee, colas).
Pacritinib: (Moderate) Monitor for an increase in caffeine-related adverse reactions, including nervousness, irritability, insomnia, tachycardia, or tremor, if concomitant use of pacritinib is necessary; lower caffeine doses may be necessary. Concomitant use may increase caffeine exposure; caffeine is a CYP1A2 substrate and pacritinib is a CYP1A2 inhibitor.
Peginterferon Alfa-2b: (Moderate) The effects of peginterferon alfa-2b on CYP1A2 were evaluated in drug interaction studies. Administration of peginterferon alfa-2b with caffeine, a CYP1A2 substrate, resulted in an 18% to 39% increase in the geographic mean exposure for caffeine, suggesting inhibition of CYP1A2. Monitor for adverse effects associated with increased exposure to caffeine if peginterferon alfa-2b is coadministered with caffeine.
Penicillin G Benzathine; Penicillin G Procaine: (Moderate) Coadministration of penicillin G procaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue penicillin G procaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Penicillin G Procaine: (Moderate) Coadministration of penicillin G procaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue penicillin G procaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Pentobarbital: (Moderate) Caffeine has been reported to increase the metabolism of barbiturates, and barbiturates increase caffeine elimination. Higher caffeine doses may be needed after barbiturate administration. (Minor) Chronic therapy with barbiturates can increase the metabolism and decrease the effectiveness of acetaminophen. During acute overdoses, barbiturates can enhance the formation of toxic acetaminophen metabolites.
Phendimetrazine: (Moderate) Caffeine is a CNS-stimulant and such actions are expected to be additive when coadministered with other CNS stimulants or psychostimulants.
Phenelzine: (Major) Excessive use of caffeine in any form should be avoided in patients receiving Monoamine oxidase inhibitors (MAOIs). Limit caffeine intake during MAOI use and for 1 to 2 weeks after discontinuation of any MAOI. The use of non-prescription medicines or dietary supplements containing caffeine should be avoided. Patients should try to avoid or limit the intake of all items containing caffeine such as tea, coffee, chocolate, and cola. Cardiac arrhythmias or severe hypertension may occur because of the potentiation of caffeine's sympathomimetic effects by MAOIs if caffeine intake is excessive.
Phenobarbital: (Moderate) Caffeine has been reported to increase the metabolism of barbiturates, and barbiturates increase caffeine elimination. Higher caffeine doses may be needed after barbiturate administration. (Minor) Chronic therapy with barbiturates can increase the metabolism and decrease the effectiveness of acetaminophen. During acute overdoses, barbiturates can enhance the formation of toxic acetaminophen metabolites.
Phenobarbital; Hyoscyamine; Atropine; Scopolamine: (Moderate) Caffeine has been reported to increase the metabolism of barbiturates, and barbiturates increase caffeine elimination. Higher caffeine doses may be needed after barbiturate administration. (Minor) Chronic therapy with barbiturates can increase the metabolism and decrease the effectiveness of acetaminophen. During acute overdoses, barbiturates can enhance the formation of toxic acetaminophen metabolites.
Phentermine: (Moderate) Caffeine is a CNS-stimulant and such actions are expected to be additive when coadministered with other CNS stimulants or psychostimulants.
Phentermine; Topiramate: (Moderate) Caffeine is a CNS-stimulant and such actions are expected to be additive when coadministered with other CNS stimulants or psychostimulants.
Phenylephrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants like phenylephrine; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Phenytoin: (Moderate) Higher caffeine doses may be needed after hydantoin administration; hydantoins increase caffeine elimination. (Minor) Hydantoin anticonvulsants induce hepatic microsomal enzymes and may increase the metabolism of other drugs, leading to reduced efficacy of medications like acetaminophen. In addition, the risk of hepatotoxicity from acetaminophen may be increased with the chronic dosing of acetaminophen along with phenytoin. Adhere to recommended acetaminophen dosage limits. Acetaminophen-related hepatotoxicity has occurred clinically with the concurrent use of acetaminophen 1300 mg to 6200 mg daily and phenytoin. Acetaminophen cessation led to serum transaminase normalization within 2 weeks.
Pneumococcal Vaccine, Polyvalent: (Moderate) Concomitant administration of antipyretics, such as acetaminophen, may decrease an individual's immunological response to the pneumococcal vaccine. A post-marketing study conducted in Poland using a non-US vaccination schedule (2, 3, 4, and 12 months of age) evaluated the impact of prophylactic oral acetaminophen on antibody responses to Prevnar 13. Data show that acetaminophen, given at the time of vaccination and then dosed at 6 to 8 hour intervals for 3 doses on a scheduled basis, reduced the antibody response to some serotypes after the third dose of Prevnar 13 when compared to the antibody responses of infants who only received antipyretics 'as needed' for treatment. However, reduced antibody responses were not observed after the fourth dose of Prevnar 13 with prophylactic acetaminophen.
Posaconazole: (Moderate) Posaconazole and acetaminophen should be coadministered with caution due to an increased potential for acetaminophen-related adverse events. Posaconazole is a potent inhibitor of CYP3A4, an isoenzyme partially responsible for the metabolism of acetaminophen. These drugs used in combination may result in elevated acetaminophen plasma concentrations, causing an increased risk for acetaminophen-related adverse events.
Pramlintide: (Minor) Because pramlintide has the potential to delay the absorption of concomitantly administered medications, medications should be administered at least 1 hour before or 2 hours after pramlintide injection when the rapid onset of a concomitantly administered oral medication is a critical determinant of effectiveness (i.e., analgesics).
Prilocaine: (Moderate) Coadministration of prilocaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue prilocaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Prilocaine; Epinephrine: (Moderate) Caffeine is a CNS-stimulant and such actions are expected to be additive when coadministered with other CNS stimulants or psychostimulants. (Moderate) Coadministration of prilocaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue prilocaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Primidone: (Moderate) Caffeine has been reported to increase the metabolism of barbiturates, and barbiturates increase caffeine elimination. Higher caffeine doses may be needed after barbiturate administration. (Minor) Chronic therapy with barbiturates can increase the metabolism and decrease the effectiveness of acetaminophen. During acute overdoses, barbiturates can enhance the formation of toxic acetaminophen metabolites.
Procarbazine: (Major) Ingestion of certain products should be minimized while receiving procarbazine therapy, as the drug has some MAO inhibiting actions. Caffeine may produce hypertension or hypertensive crisis or induce cardiac arrhythmias if administered to patients taking drugs with strong MAOI properties. All preparations containing caffeine should be used sparingly such as teas, coffee, chocolate, cola, guarana, or 'stay awake' products. Some non-prescription medicines also contain caffeine and should not be taken without health care professional advice. Following discontinuation of procarbazine, dietary restrictions should continue for at least 2 weeks due to the slow recovery from the enzyme-inhibiting effects.
Promethazine; Phenylephrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants like phenylephrine; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Pseudoephedrine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Pseudoephedrine; Triprolidine: (Moderate) CNS-stimulating actions of caffeine can be additive with other CNS stimulants or psychostimulants; caffeine should be avoided or used cautiously. Excessive caffeine ingestion (via medicines, supplements or beverages including coffee, green tea, other teas, guarana, colas) may contribute to side effects like nervousness, irritability, insomnia, or tremor.
Quazepam: (Minor) Patients taking benzodiazepines for insomnia should not use caffeine-containing products prior to going to bed as these products may antagonize the sedative effects of the benzodiazepine.
Racepinephrine: (Moderate) Patients who are using racepinephrine inhalation are advised to avoid foods and beverages that contain caffeine. They should also avoid dietary supplements containing ingredients, such as caffeine, that are reported or claimed to have a stimulant effect. If a patient is taking prescribed medications containing caffeine, then they should seek health care professional advice prior to the use of racepinephrine. Additive adverse effects on the cardiovascular and nervous system are possible, some which may be undesirable. Side effects such as nausea, tremor, nervousness, difficulty with sleep, and increased heart rate may be additive. Consider alternatives to racepinephrine for the treatment of asthma.
Ramelteon: (Minor) Caffeine is a central nervous system (CNS) stimulant. Patients taking melatonin or the melatonin analogs (ramelteon, tasimelteon) for sleep should avoid caffeine-containing medications, dietary supplements, foods, and beverages close to bedtime. Patients should be encouraged to avoid excessive total daily caffeine intake, as part of proper sleep hygiene, since caffeine intake can interfere with proper sleep.
Rasagiline: (Moderate) Although sympathomimetics and psychostimulants are contraindicated for use with other monoamine oxidase inhibitors (MAOIs), hypertensive reactions generally are not expected to occur during concurrent use with rasagiline because of the selective monoamine oxidase-B (MAO-B) inhibition of rasagiline at manufacturer recommended doses.
Regadenoson: (Major) Caffeine is a non-specific adenosine receptor antagonist and can interfere with the efficacy of regadenoson. Patients should avoid consumption of any products containing caffeine (including caffeine from foods and beverages such as coffee, green tea, other teas, colas, and chocolate) for at least 12 hours before regadenoson administration.
Remimazolam: (Minor) Patients taking benzodiazepines for insomnia should not use caffeine-containing products prior to going to bed as these products may antagonize the sedative effects of the benzodiazepine.
Rifabutin: (Moderate) As a cytochrome P450 isoenzyme inducers, rifabutin could induce the metabolism of acetaminophen. An increase in acetaminophen-induced hepatotoxicity may be seen by increasing the metabolism of acetaminophen to its toxic metabolite, NAPQI. Also, the analgesic activity of acetaminophen may be reduced.
Rifampin: (Moderate) Concomitant use of acetaminophen with rifampin may increase the known risk of hepatotoxicity in relation to each drug. Severe hepatic dysfunction including fatalities were reported in patients taking rifampin with other hepatotoxic agents. (Minor) Rifampin is a potent inducer of the cytochrome P450 hepatic enzyme system and can reduce the plasma concentrations and possibly the efficacy of caffeine, including caffeine found in green tea products.
Ritlecitinib: (Moderate) Monitor for an increase in caffeine-related adverse reactions, including nervousness, irritability, insomnia, tachycardia, or tremor, if concomitant use of ritlecitinib is necessary; lower caffeine doses may be necessary. Concomitant use has been observed to increase caffeine overall exposure by 2.65-fold; caffeine is a CYP1A2 substrate and ritlecitinib is a CYP1A2 inhibitor.
Ritonavir: (Moderate) Concurrent administration of acetaminophen with ritonavir may result in elevated acetaminophen plasma concentrations and subsequent adverse events. Acetaminophen is metabolized by the hepatic isoenzyme CYP3A4; ritonavir is an inhibitor of this enzyme. Caution and close monitoring are advised if these drugs are administered together.
Ropivacaine: (Moderate) Coadministration of ropivacaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue ropivacaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Rucaparib: (Moderate) Monitor for an increase in caffeine-related adverse reactions if coadministration with rucaparib is necessary. Some patients may need to reduce or limit their caffeine intake. Caffeine is a sensitive CYP1A2 substrate and rucaparib is a weak CYP1A2 inhibitor. Concomitant use increased the AUC of caffeine by 2.6-fold.
Salmeterol: (Moderate) Caffeine may enhance the cardiac inotropic effects of beta-agonists.
Secobarbital: (Moderate) Caffeine has been reported to increase the metabolism of barbiturates, and barbiturates increase caffeine elimination. Higher caffeine doses may be needed after barbiturate administration. (Minor) Chronic therapy with barbiturates can increase the metabolism and decrease the effectiveness of acetaminophen. During acute overdoses, barbiturates can enhance the formation of toxic acetaminophen metabolites.
Segesterone Acetate; Ethinyl Estradiol: (Moderate) Monitor for estrogen-related adverse effects during concomitant acetaminophen and ethinyl estradiol use. Acetaminophen may increase plasma ethinyl estradiol concentrations, possibly by inhibition of conjugation. (Minor) Serum concentrations of caffeine may be increased during concurrent administration with ethinyl estradiol. Patients may desire to limit products that contain high amounts of caffeine to minimize caffeine-related side effects such as nausea or tremors.
Selegiline: (Moderate) Although psychostimulants are contraindicated for use with other monoamine oxidase inhibitors (MAOIs), hypertensive reactions generally are not expected to occur during concurrent use with selegiline because of the selective monoamine oxidase-B (MAO-B) inhibition of selegiline at manufacturer recommended doses. However, cardiac arrhythmias or severe hypertension is possible if doses are exceeded or caffeine intake is excessive.
Serdexmethylphenidate; Dexmethylphenidate: (Moderate) Caffeine is a CNS stimulant and such actions are expected to be additive when coadministered with other CNS stimulants or psychostimulants. Avoid excessive caffeine intake during use of methylphenidate or its derivatives. Excessive caffeine ingestion (via medicines, foods like chocolate, dietary supplements, or beverages including coffee, green tea, other teas, colas) may contribute to side effects like nervousness, irritability, nausea, insomnia, or tremor. Patients should avoid medications and dietary supplements which contain high amounts of caffeine.
Sodium Bicarbonate: (Minor) Antacids can delay the oral absorption of acetaminophen, but the interactions are not likely to be clinically significant as the extent of acetaminophen absorption is not appreciably affected.
Sodium Oxybate: (Moderate) Caffeine should be avoided or used cautiously with oxybates. Monitor for potential side effects such as nervousness, irritability, insomnia, and/or cardiac arrhythmias.
Solifenacin: (Minor) Consuming > 400 mg/day caffeine has been associated with the development of urinary incontinence. Beverages containing caffeine may aggravate bladder symptoms, increase urine output, and counteract the effectiveness of solifenacin to some degree. Patients may wish to limit their intake of caffeinated drugs, dietary supplements, or beverages.
Solriamfetol: (Moderate) Monitor blood pressure and heart rate during coadministration of solriamfetol, a norepinephrine and dopamine reuptake inhibitor, and caffeine. Concurrent use of solriamfetol and other medications that increase blood pressure and/or heart rate may increase the risk of such effects. Coadministration of solriamfetol with other drugs that increase blood pressure or heart rate has not been evaluated.
St. John's Wort, Hypericum perforatum: (Moderate) Inducers of CYP1A2, such as St. John's wort, Hypericum perforatum, may induce the hepatic oxidative metabolism of caffeine. (Minor) St. John's wort, Hypericum perforatum induces cytochrome P450 1A2. About 10 to 15% of the acetaminophen dose undergoes oxidative metabolism via cytochrome P450 isoenzymes CYP2E1, 3A4 and 1A2, which produces the hepatotoxic metabolite, N-acetyl-p-benzoquinonimine. Thus, theoretically St. John's wort might increase the risk of acetaminophen-induced hepatotoxicity by increasing the metabolism of acetaminophen to NAPQI.
Stiripentol: (Moderate) Consider a dose adjustment of caffeine when coadministered with stiripentol. Coadministration may alter plasma concentrations of caffeine resulting in an increased risk of adverse reactions and/or decreased efficacy. Caffeine is a sensitive CYP1A2 substrate. In vitro data predicts inhibition or induction of CYP1A2 by stiripentol potentially resulting in clinically significant interactions.
Suvorexant: (Minor) Caffeine is a central nervous system (CNS) stimulant. Patients taking medications for sleep, such as suvorexant, eszopiclone, zaleplon, or zolpidem should avoid caffeine-containing medications, dietary supplements, foods, and beverages close to bedtime. Patients should be encouraged to avoid excessive total daily caffeine intake, as part of proper sleep hygiene, since caffeine intake can interfere with proper sleep.
Tasimelteon: (Minor) Caffeine is a central nervous system (CNS) stimulant. Patients taking melatonin or the melatonin analogs (ramelteon, tasimelteon) for sleep should avoid caffeine-containing medications, dietary supplements, foods, and beverages close to bedtime. Patients should be encouraged to avoid excessive total daily caffeine intake, as part of proper sleep hygiene, since caffeine intake can interfere with proper sleep.
Temazepam: (Minor) Patients taking benzodiazepines for insomnia should not use caffeine-containing products prior to going to bed as these products may antagonize the sedative effects of the benzodiazepine.
Terbinafine: (Minor) Terbinafine has been shown to inhibit the clearance of caffeine. The clinical significance of this interaction has not been determined.
Terbutaline: (Moderate) Caffeine may enhance the cardiac inotropic effects of beta-agonists.
Teriflunomide: (Minor) Monitor for decreased efficacy of caffeine during coadministration of teriflunomide. Teriflunomide may be a weak inducer of CYP1A2. When teriflunomide was given concurrently with caffeine in vivo, a CYP1A2 substrate, the Cmax and AUC of caffeine decreased by 18% and 55%, respectively.
Tetracaine: (Moderate) Coadministration of tetracaine with oxidizing agents, such as acetaminophen, may increase the risk of developing methemoglobinemia. Monitor patients closely for signs and symptoms of methemoglobinemia if coadministration is necessary. If methemoglobinemia occurs or is suspected, discontinue tetracaine and any other oxidizing agents. Depending on the severity of symptoms, patients may respond to supportive care; more severe symptoms may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen.
Theophylline, Aminophylline: (Major) Caffeine is a CNS stimulant. The concurrent administration of caffeine to patients taking aminophylline may produce excessive caffeine-like side effects, such as nausea, irritability or nervousness. Adverse effects such as tremors, insomnia, seizures, or cardiac arrhythmias are also possible when excessive dosages of caffeine are taken concurrently. Patients should avoid medications containing caffeine when possible. Patients may also need to limit their intake of caffeine-containing beverages or foods (e.g., coffee, green tea, other teas, colas, or chocolate) to avoid caffeine-like side effects. (Major) Caffeine is a CNS stimulant. The concurrent administration of caffeine to patients taking theophylline may produce excessive caffeine-like side effects, such as nausea, irritability or nervousness. Adverse effects such as tremors, insomnia, seizures, or cardiac arrhythmias are also possible when excessive dosages of caffeine are taken concurrently with theophylline. Patients taking theophylline should avoid medications containing caffeine when possible. Patients may also need to limit their intake of caffeine-containing beverages or foods (e.g., coffee, green tea, other teas, colas, or chocolate) to avoid caffeine-like side effects. In neonates, theophylline is metabolized to caffeine; initiating caffeine after theophylline therapy is halted may result in caffeine toxicity in neonates if serum caffeine levels are not monitored prior to the initiation of caffeine therapy. Concurrent use of theophylline with caffeine in neonates is not recommended due to the potential for additive toxicity.
Tiotropium; Olodaterol: (Moderate) Caffeine may enhance the cardiac inotropic effects of beta-agonists.
Tizanidine: (Minor) Tizanidine delays the time to attain peak concentrations of acetaminophen by about 16 minutes. The clinical significance of this interaction is unknown.
Tobacco: (Major) Advise patients who are taking caffeine to avoid smoking tobacco. Smoking tobacco has been observed to increase caffeine clearance by 50% to 70%. Caffeine is a CYP1A2 substrate and smoking tobacco induces CYP1A2.
Tolterodine: (Minor) Beverages containing caffeine may aggravate bladder symptoms and counteract the effectiveness of tolterodine to some degree. Patients may wish to limit their intake of caffeinated drugs, dietary supplements, or beverages.
Trandolapril; Verapamil: (Minor) Verapamil reduces the clearance of caffeine and increases serum caffeine concentrations, presumably via inhibition of hepatic metabolism. During concomitant therapy with verapamil, it may be prudent to advise patients to limit or minimize the intake of caffeinated products to minimize caffeine-related side effects.
Tranylcypromine: (Major) Excessive use of caffeine in any form should be avoided in patients receiving Monoamine oxidase inhibitors (MAOIs). Limit caffeine intake during MAOI use and for 1 to 2 weeks after discontinuation of any MAOI. The use of non-prescription medicines or dietary supplements containing caffeine should be avoided. Patients should try to avoid or limit the intake of all items containing caffeine such as tea, coffee, chocolate, and cola. Cardiac arrhythmias or severe hypertension may occur because of the potentiation of caffeine's sympathomimetic effects by MAOIs if caffeine intake is excessive.
Triazolam: (Minor) Patients taking benzodiazepines for insomnia should not use caffeine-containing products prior to going to bed as these products may antagonize the sedative effects of the benzodiazepine.
Umeclidinium; Vilanterol: (Moderate) Caffeine may enhance the cardiac inotropic effects of beta-agonists.
Vemurafenib: (Moderate) Concomitant use of vemurafenib and acetaminophen may result in altered concentrations of acetaminophen. Vemurafenib is an inhibitor of CYP1A2 and CYP2A6, and an inducer of CYP3A4. Acetaminophen is a substrate of CYP1A2, CYP2A6, and CYP3A4. Use caution and monitor patients for toxicity and efficacy.
Verapamil: (Minor) Verapamil reduces the clearance of caffeine and increases serum caffeine concentrations, presumably via inhibition of hepatic metabolism. During concomitant therapy with verapamil, it may be prudent to advise patients to limit or minimize the intake of caffeinated products to minimize caffeine-related side effects.
Viloxazine: (Moderate) Monitor for an increase in caffeine-related adverse reactions, including nervousness, irritability, insomnia, tachycardia, or tremor, if concomitant use of viloxazine is necessary; lower caffeine doses may be necessary. Concomitant use may increase caffeine exposure; caffeine is a CYP1A2 substrate and viloxazine is a CYP1A2 inhibitor.
Warfarin: (Minor) Although acetaminophen is routinely considered safer than aspirin and agent of choice when a mild analgesic/antipyretic is necessary for a patient receiving therapy with warfarin, acetaminophen has also been shown to augment the hypoprothrombinemic response to warfarin. Concomitant acetaminophen ingestion may result in increases in the INR in a dose-related fashion. Clinical bleeding has been reported. Single doses or short (i.e., several days) courses of treatment with acetaminophen are probably safe in most patients taking warfarin. Clinicians should be alert for an increased INR if acetaminophen is administered in large daily doses for longer than 10 to 14 days.
Zaleplon: (Minor) Caffeine is a central nervous system (CNS) stimulant. Patients taking medications for sleep, such as zaleplon should avoid caffeine-containing medications, dietary supplements, foods, and beverages close to bedtime. Patients should be encouraged to avoid excessive total daily caffeine intake, as part of proper sleep hygiene, since caffeine intake can interfere with proper sleep.
Zidovudine, ZDV: (Minor) Both acetaminophen and zidovudine, ZDV undergo glucuronidation. Competition for the metabolic pathway is thought to have caused a case of acetaminophen-related hepatotoxicity. This interaction may be more clinically significant in patients with depleted glutathione stores, such as patients with acquired immunodeficiency syndrome, poor nutrition, or alcoholism.
Zileuton: (Moderate) Monitor for an increase in caffeine-related adverse reactions, including nervousness, irritability, insomnia, tachycardia, or tremor, if concomitant use of zileuton is necessary; lower caffeine doses may be necessary. Concomitant use may increase caffeine exposure; caffeine is a CYP1A2 substrate and zileuton is a CYP1A2 inhibitor.
Zolmitriptan: (Minor) Zolmitriptan can delay the Tmax of acetaminophen by one hour. A single 1 g dose of acetaminophen does not alter the pharmacokinetics of zolmitriptan and its active metabolite. The interaction between zolmitriptan and acetaminophen is not likely to be clinically significant.
Zolpidem: (Minor) Caffeine is a central nervous system (CNS) stimulant. Patients taking medications for sleep, such as zolpidem should avoid caffeine-containing medications, dietary supplements, foods, and beverages within the hours close to bedtime. Patients should be encouraged to avoid excessive total daily caffeine intake, as part of proper sleep hygiene, since caffeine intake can interfere with proper sleep. However, in healthy subjects (without insomnia) in a pharmacokinetic study, coadministration of caffeine at a dosage of 150 to 300 mg with zolpidem did not counteract the sedative effects of a single 10 mg dose of zolpidem.
Although the exact mechanism of action is unknown, acetaminophen is thought to mediate its actions centrally through activation of the descending serotonergic pathways. It is believed that acetaminophen increases the pain threshold by inhibiting prostaglandin (PG) synthesis through the cyclooxygenase (COX) pathway, similar to nonsteroidal anti-inflammatory drugs (NSAIDs). Though acetaminophen's analgesic and antipyretic properties are similar to those of NSAIDs, acetaminophen does not have significant anti-inflammatory or antiplatelet effects. It has been suggested acetaminophen may inhibit a specific site on the prostaglandin H2 synthetase (PGHS) molecule; the 2 major forms of this enzyme, PGHS1 and PGHS2, are commonly referred to as COX-1 and COX-2. PGHS has 2 active sites, COX and peroxidase (POX). It is thought acetaminophen acts as a reducing co-substrate at the POX site and interferes with the conversion of arachidonic acid to PGH2, thereby inhibiting PG synthesis. Other potential mechanisms may involve inhibition of the nitric oxide pathway mediated by a variety of neurotransmitter receptors (e.g., N-methyl-D-aspartate and substance p) and indirect activation of cannabinoid receptors. Acetaminophen produces its antipyretic effect by inhibiting PG synthesis in the central nervous system and blocking the actions of endogenous pyrogens at the hypothalamic thermoregulatory centers. Caffeine causes cerebral vasoconstriction, which decreases blood flow and oxygen tension. In combination with acetaminophen, caffeine may provide a quicker onset of action and enhance pain relief allowing for lower doses of analgesics.
Acetaminophen; Caffeine combination products are administered orally. Acetaminophen and caffeine are both metabolized in the liver.
-Acetaminophen: At therapeutic concentrations, protein binding is approximately 10% to 25%. Acetaminophen is widely distributed throughout most body tissues except fat; low protein binding and molecular weight allow blood-brain barrier penetration. The volume of distribution is approximately 1 L/kg. Acetaminophen is primarily metabolized in the liver by first-order kinetics and involves 3 separate pathways: glucuronidation, sulfate conjugation, and cytochrome P450 (CYP450) oxidation. Glucuronidation and sulfate conjugation are the major routes of metabolism, while a small amount of drug undergoes oxidative metabolism via CYP2E1 producing the hepatotoxic metabolite, N-acetyl-p-benzoquinone imine (NAPQI). At therapeutic doses, NAPQI is rapidly conjugated with glutathione to form inert cysteine and mercapturic acid metabolites. CYP1A2 and CYP3A4 appear to have a minor role in the metabolism of acetaminophen. Supratherapeutic or repeated therapeutic doses of acetaminophen, fasting, and alcoholism may deplete glutathione stores, leading to increased concentrations of NAPQI and hepatotoxicity. The elimination half-life of acetaminophen is 2 to 3 hours in healthy adult patients. Acetaminophen is renally excreted primarily as the glucuronide conjugate (40% to 65%) and sulfate metabolite (25% to 35%). Mercapturic acid and cysteine metabolites account for 5% to 12% of the urinary metabolites; less than 5% is excreted as unchanged drug.
-Caffeine: Caffeine is rapidly distributed to all body tissues and readily crosses the blood-brain barrier. Caffeine is roughly 36% bound to plasma proteins; the volume of distribution is 630 mL/kg, and the clearance is 90 mL/hour/kg. Caffeine is partially metabolized in the liver via demethylation reactions dependent on CYP1A2; major metabolites include paraxanthine (80%), theobromine (10%), and theophylline (4%). The plasma half-life is 3 to 7 hours in adults.
Affected cytochrome P450 isoenzymes and drug transporters: CYP1A2, CYP2E1
Although acetaminophen is primarily metabolized via glucuronidation and sulfate conjugation, it is also a substrate of CYP2E1. Drugs that induce CYP2E1 may increase the metabolism of acetaminophen to its toxic metabolite and therefore increase the risk of hepatotoxicity. Because CYP1A2 and CYP3A4 have a negligible contribution to acetaminophen metabolism, the enzymes are unlikely to affect toxic metabolite formation. Caffeine is a substrate of CYP1A2.
-Route-Specific Pharmacokinetics
Oral Route
-Acetaminophen: Immediate-release acetaminophen is rapidly and almost completely absorbed from the gastrointestinal tract, primarily the small intestine. Bioavailability ranges from 85% to 98%. Peak plasma concentrations occur within 30 to 60 minutes and range from 7.7 to 17.6 mcg/mL after a single 1,000 mg dose and 7.9 to 27 mcg/mL at steady-state after 1,000 mg every 6 hours in adult patients.
-Caffeine: Caffeine is well absorbed from the GI tract. After oral administration, peak plasma concentrations in adults are observed at approximately 30 to 60 minutes following oral administration.
-Special Populations
Hepatic Impairment
-Acetaminophen: The half-life of acetaminophen can be prolonged in patients with hepatic disease.
-Caffeine: Caffeine elimination may be reduced in patients with hepatic impairment.
Renal Impairment
-Acetaminophen: In severe renal impairment (CrCl 10 to 30 mL/minute), the elimination of acetaminophen is slightly delayed, with a half-life of 2 to 5.3 hours. In addition, the elimination of sulfate and glucuronide conjugates is 3 times slower in patients with severe renal impairment than in healthy subjects, leading to potential accumulation.
-Caffeine: Caffeine elimination may be reduced in patients with renal impairment.