Cimetidine
Pronounced
"sye-MET-uh-deen"
Drug Interactions
See also How to Use section.
Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.
Some products that may interact with this drug include: dofetilide, epirubicin, ticlopidine, artemether, clopidogrel, lumefantrine, metformin, moclobemide, moricizine, quinidine, silver sulfadiazine.
This medication can slow down the removal of other medications from your body, which may affect how they work. Examples of affected drugs include fezolinetant, metoprolol, tacrine, warfarin, zaleplon, calcium channel blockers (such as diltiazem), tricyclic antidepressants (such as amitriptyline), theophylline, among others.
Since cimetidine reduces the amount of acid in your stomach, it may also change the absorption of certain medications and affect how they work. Some examples of affected drugs include atazanavir, dasatinib, certain azole antifungals (such as itraconazole, ketoconazole), levoketoconazole, pazopanib, sparsentan, among others. Ask your doctor or pharmacist if any of the medications you take are affected by cimetidine and how to manage this interaction.
Cigarette smoking can affect this medication. Tell your doctor if you smoke and if you stop or start smoking while using this medication.
This medication and similar H2 blockers (such as famotidine, nizatidine, ranitidine) are available both with and without a prescription. Do not take them at the same time.
Negative Interactions
2- Potential Negative Interaction
Cimetidine
Foods with Caffeine
Caffeine is found in coffee, tea, soft drinks, chocolate, guaraná (Paullinia cupana), nonprescription over-the-counter drug products, and supplement products containing caffeine or guaraná. Cimetidine may decrease the clearance of caffeine from the body, causing increased caffeine blood levels and unwanted actions. People taking cimetidine may choose to limit their caffeine intake to avoid problems. They should read food, beverage, drug, and supplement labels carefully for caffeine content.
Foods with CaffeineCimetidine- Threlkeld DS, ed. Central Nervous System Drugs, Analeptics, Caffeine. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, Feb 1998, 230-d.
- Reduces Effectiveness
Cimetidine
Magnesium
In healthy volunteers, a magnesium hydroxide/aluminum hydroxide antacid, taken with cimetidine, decreased cimetidine absorption by 20 to 25%. People can avoid this interaction by taking cimetidine two hours before or after any aluminum/magnesium-containing antacids, including magnesium hydroxide found in some vitamin/mineral supplements. However, the available studies do not clearly indicate if magnesium hydroxide was the problem and may not need to be avoided.
MagnesiumCimetidine- Bachmann KA, Sullivan TJ, Jauregui L, et al. Drug interactions of H2-receptor antagonists. Scand J Gastroenterol Suppl 1994;206:14-9.
Supportive Interactions
6- Replenish Depleted Nutrients
Cimetidine
Beta-Carotene
This interaction is based on this drug belonging to a drug class. While this drug may differ from the text and references below, drugs within this class work in a similar way and this interaction is applicable to drugs within the same class.
Omeprazole, a drug closely related to lansoprazole, taken for seven days led to a near-total loss of stomach acid in healthy people and interfered with the absorption of a single administration of 120 mg of beta-carotene. It is unknown whether repeated administration of beta-carotene would overcome this problem or if absorption of carotenoids from food would be impaired. Persons taking omeprazole and related acid-blocking drugs for long periods may want to have carotenoid blood levels checked, eat plenty of fruits and vegetables, and consider supplementing with carotenoids.
Beta-CaroteneCimetidine- Tang G, Serfaty-Lacronsniere C, Camilo ME, Russell RM. Gastric acidity influences the blood response to a beta-carotene dose in humans. Am J Clin Nutr 1996;64:622-6.
- Replenish Depleted Nutrients
Cimetidine
Copper
This interaction is based on this drug belonging to a drug class. While this drug may differ from the text and references below, drugs within this class work in a similar way and this interaction is applicable to drugs within the same class.
There is some evidence that other vitamins and minerals, such as folic acid and copper, require the presence of stomach acid for optimal absorption. Long-term use of H-2 blockers may therefore promote a deficiency of these nutrients. Individuals requiring long-term use of H-2 blockers may therefore benefit from a multiple vitamin/mineral supplement.
CopperCimetidine- Russell RM, Krasinski SD, Samloff IM. Correction of impaired folic acid (Pte Glu) absorption by orally administered HCl in subjects with gastric atrophy. Am J Clin Nutr 1984;39:656.
- Tompsett SL. Factors influencing the absorption of iron and copper from the alimentary tract. Biochem J 1940;34:961-9.
- Replenish Depleted Nutrients
Cimetidine
Folic Acid
This interaction is based on this drug belonging to a drug class. While this drug may differ from the text and references below, drugs within this class work in a similar way and this interaction is applicable to drugs within the same class.
Folic acid is needed by the body to utilize vitamin B12. Antacids, including nizatidine, inhibit folic acid absorption. However, folic acid supplementation can mask a vitamin B12 deficiency. Therefore, people taking antacids are advised to supplement with folic acid and vitamin B12.
There is some evidence that other vitamins and minerals, such as folic acid and copper, require the presence of stomach acid for optimal absorption. Long-term use of H-2 blockers may therefore promote a deficiency of these nutrients. Individuals requiring long-term use of H-2 blockers may therefore benefit from a multiple vitamin/mineral supplement.
Folic AcidCimetidine- Russell RM, Golner BB, Krasinski SD, et al. Effect of antacid and H2 receptor antagonists on the intestinal absorption of folic acid. J Lab Clin Med 1988;112:458-63.
- Russell RM, Krasinski SD, Samloff IM. Correction of impaired folic acid (Pte Glu) absorption by orally administered HCl in subjects with gastric atrophy. Am J Clin Nutr 1984;39:656.
- Tompsett SL. Factors influencing the absorption of iron and copper from the alimentary tract. Biochem J 1940;34:961-9.
- Replenish Depleted Nutrients
Cimetidine
Iron
Stomach acid may facilitate iron absorption. H-2 blocker drugs reduce stomach acid and are associated with decreased dietary iron absorption. People with ulcers may also be iron deficient due to blood loss and benefit from iron supplementation. Iron levels in the blood can be checked with lab tests.
IronCimetidine- Aymard JP, Aymard B, Netter P, et al. Haematological adverse effects of histamine H2-receptor antagonists.Med Toxicol Adverse Drug Exp 1988;3:430-48.
- Replenish Depleted Nutrients
Cimetidine
Vitamin B12
Hydrochloric acid is needed to release vitamin B12 from food so it can be absorbed by the body. Cimetidine, which reduces stomach acid, may decrease the amount of vitamin B12 available for the body to absorb. The vitamin B12 found in supplements is available to the body without the need for stomach acid. Lab tests can determine vitamin B12 levels in people.
Vitamin B12Cimetidine- Salom IL, Silvis SE, Doscherholmen A. Effect of cimetidine on the absorption of vitamin B12. Scand J Gastroenterol 1982;17:129-31.
- Replenish Depleted Nutrients
Cimetidine
Vitamin D
Cimetidine may reduce vitamin D activation by the liver. Lab tests can measure activated vitamin D levels in the blood. Forms of vitamin D that do not require liver activation are available, but only by prescription.
Vitamin DCimetidine- Anonymous. Cimetidine inhibits the hepatic hydroxylation of vitamin D. Nutr Rev 1985;43:184-5 [review].
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