Guaifenesin is an oral expectorant, which is commonly used to treat cough due to colds and minor upper respiratory infections. Despite its long history of use since the 1950s, the efficacy of guaifenesin has only recently been substantiated. Guaifenesin is used for dry, nonproductive cough when there is the presence of tenacious mucus and/or mucus plugs. The results of a few studies have favored active treatment with guaifenesin over placebo in treating productive cough due to upper respiratory illness (URI). In patients with chronic bronchitis, guaifenesin, is not recommended for aiding with cough suppression since studies have shown no benefit in reducing cough. However, the mucolytic properties of guaifenesin may be independently helpful in clearing mucus, and patients may subjectively report benefit to use. Guaifenesin is an ingredient contained in many combination non-prescription (over-the-counter or OTC) and prescription cough and cold products.
General Administration Information
For storage information, see the specific product information within the How Supplied section.
Route-Specific Administration
Oral Administration
-To assist expectoration, patients should have an adequate intake of fluids while taking guaifenesin.
Oral Solid Formulations
-Extended-release tablets: Swallow whole; do not crush, break, or chew. Take with a full glass of water. May be given with or without food.
-Oral granules: Open packet, sprinkle entire contents onto tongue, and swallow. For best taste, do not chew granules. Liquid is not necessary for administration.
Oral Liquid Formulations
-Oral solutions: Administer using a calibrated measuring device to ensure accurate dosage.
In general, adverse reactions to guaifenesin are infrequent and usually not serious. With recommended doses, adverse GI effects are rare. When given in high or excessive dosage, nausea, vomiting, diarrhea, and/or abdominal pain may occur. Drowsiness, dizziness, and headache occur rarely at therapeutic doses of guaifenesin. Rash (unspecified) has also been reported with guaifenesin products.
Excessive use or dosage of guaifenesin may result in nephrolithiasis; the resulting renal stones have been documented to contain guaifenesin metabolites including the active metabolite, beta-(2-methoxyphenoxy)-lactic acid. In another report, 11 of 24 patients with kidney stones containing the guaifenesin metabolite, beta-(2-methoxyphenoxy)-lactic acid, were using excessive amounts of over-the-counter stimulants and bronchodilators (stated dosages of 3 to 120 tablets/day or approximately 600 to 24,000 mg/day of guaifenesin); some patients had a history of substance abuse.
Guaifenesin may alter some laboratory tests. It may increase renal clearance for urate and lower serum uric acid levels. Guaifenesin may produce an increase in urinary 5-hydroxyindoleacetic acid and may therefore interfere with the interpretation of this diagnostic test for carcinoid syndrome. Guaifenesin may also falsely elevate the VMA test for catechols. Guaifenesin should be discontinued at least 48 hours prior to the collection of urine specimens for such laboratory tests.
Guaifenesin should not be used for persistent or chronic cough such as occurs with tobacco smoking, asthma, emphysema, or chronic bronchitis or any other condition where cough is associated with excessive secretions, unless under the supervision of a health care professional. Guaifenesin should not be used for a cough that is specifically associated with heart failure or ACE inhibitor therapy.
A fever may be indicative of a serious condition. Guaifenesin should be used in patients with a high temperature only under the direction of a physician.
Guaifenesin products are not recommended for use in children and infants less than 2 years of age due to lack of evidence for safety and efficacy. Due to the risk for serious adverse reactions, the FDA recommends against administration of over the counter (OTC) cough and cold products to infants and children younger than 2 years of age. When administering OTC medications to older pediatric patients, advise caregivers to read product labels carefully, use caution when administering multiple products to avoid duplication of ingredients, and use only measuring devices specifically designed for use with medications. Thoroughly assess each patient's use of similar products, both prescription and nonprescription, to avoid duplication of therapy and the potential for inadvertent overdose.
Safe use of guaifenesin in pregnancy has not been established and it is not clear if the drug crosses the placenta; guaifenesin should be given to a pregnant woman only if clearly needed. Few studies have been done to evaluate the use of expectorants during pregnancy and thus first trimester use is best avoided. Increased fluids to ease expectoration are usually recommended for first line treatment in the pregnant woman. When the drug must be administered to a pregnant woman, choose guaifenesin product formulations that are alcohol-free.
Guaifenesin should be given cautiously during breast-feeding since the effects on a nursing infant have not been formally studied. It is not known if guaifenesin is excreted into breast milk. It is unlikely that with usual maternal doses amounts in breast milk would harm the nursing infant, especially in infants over 2 months of age. Increased fluids to ease expectoration are usually recommended for first-line treatment in the lactating individual. If the use of guaifenesin is necessary, it is best to avoid the use of guaifenesin products with a high alcohol content; check product ingredients.
For the treatment of cough associated with colds and minor upper respiratory tract infections and for loosening phlegm and thin bronchial secretions to aid in clearing bronchial passages and making coughs more productive:
Oral dosage (immediate-release capsules or tablets):
Adults, Adolescents, and Children 12 years and older: 200 to 400 mg PO every 4 hours as needed. Max: 6 doses/day (2400 mg/day).
Oral dosage (extended-release or biphasic capsules or tablets):
Adults, Adolescents, and Children 12 years and older: 600 to 1200 mg PO every 12 hours as needed. Max: 2400 mg/day PO.
Oral dosage (oral solutions or syrups):
Adults and Adolescents: 200 to 400 mg PO every 4 hours as needed. Max: 2400 mg/day PO.
Children 6 to 11 years: 100 to 200 mg PO every 4 hours as needed. Max: 1200 mg/day PO.
Children 2 to 5 years: 50 to 100 mg PO every 4 hours as needed. Max: 600 mg/day PO.
Oral dosage (oral granule packets with guaifenesin 100 mg per packet; e.g., Mucinex Children's Chest Congestion Expectorant Mini-Melts):
Adults, Adolescents, and Children 12 years and older: 2 to 4 packets PO every 4 hours as needed. Do not exceed 6 doses/24 hours.
Children 6 to 11 years: 1 to 2 packets PO every 4 hours as needed. Do not exceed 6 doses/24 hours.
Children 4 to 5 years: 1 packet PO every 4 hours as needed. Do not exceed 6 doses/24 hours.
For the treatment of cervical factor infertility*, including cervical mucus thickening induced by clomiphene treatment:
Oral dosage (immediate release, alcohol-free formulations):
Adult non-pregnant females: A dosage of 200 mg PO 3 times daily during the follicular phase of the menstrual cycle (i.e., until ovulation) has been reported to be effective at thinning cervical secretions for the purpose of enhancing sperm penetration. When used with clomiphene treatment, guaifenesin use typically follows the last dose of clomiphene and continues until ovulation. Although widely reported as a potential usage, no controlled clinical trials exist. Use for this purpose is limited to the prescription by a qualified fertility specialist. Alcohol-free products should be chosen.
Maximum Dosage Limits:
-Adults
2400 mg/day PO.
-Geriatric
2400 mg/day PO.
-Adolescents
2400 mg/day PO.
-Children
12 years: 2400 mg/day PO.
6 to 11 years: 1200 mg/day PO.
2 to 5 years: 600 mg/day PO.
Less than 2 years: Safety and efficacy have not been established.
-Infants
Safety and efficacy have not been established.
Patients with Hepatic Impairment Dosing
No dosage adjustment is needed. Guaifenesin is primarily renally eliminated.
Patients with Renal Impairment Dosing
Specific guidelines for dosage adjustments in renal impairment are not available; it appears that no dosage adjustments are needed.
*non-FDA-approved indication
There are no drug interactions associated with Guaifenesin products.
Guaifenesin loosens and thins phlegm and bronchial secretions to ease expectoration. By reducing the viscosity and adhesiveness of secretions, guaifenesin increases the efficacy of the mucociliary mechanism in removing accumulated secretions from the upper and lower airway. The increased flow of less viscous secretions promotes ciliary action and changes a dry, unproductive cough to one that is more productive and less frequent. Despite its long history of use since the 1950's, the efficacy of guaifenesin has only recently been substantiated. Guaifenesin is used for dry, nonproductive cough when there is the presence of tenacious mucus and/or mucus plugs. The results of a few studies have favored active treatment with guaifenesin over placebo in treating productive cough due to upper respiratory illness (URI).
Guaifenesin is administered orally. The plasma half-life is approximately 1 hour. Guiafenesin is rapidly hydrolyzed (60% within seven hours) and then excreted in the urine, with beta-(2-methoxyphenoxy)-lactic acid as its major urinary metabolite. No unchanged drug was detected in the urine following administration. Renal stones that developed during drug therapy have been documented to contain beta-(2-methoxyphenoxy)-lactic acid and other guaifenesin metabolites. Other pharmacokinetic parameters of guaifenesin are not known.
-Route-Specific Pharmacokinetics
Oral Route
Guaifenesin is rapidly and well absorbed from the gastrointestinal tract. Extended release products (e.g., Humibid LA) release drug slowly over a period of several hours, allowing for less frequent dosing. The Mucinex brand tablet, a combination immeditate-release/extended-release product, utilizes a patented bilayer delivery system which releases guaifenesin immediately from the first layer and over 12 hours from the second layer. Guaifenesin has a plasma half-life of approximately 1 hour.