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Guaifenesin

This form:

Pronounced

"gweye-FEN-eh-sin"

Common brand names:

Benylin E, Calmylin, Koffex

Uses

Guaifenesin is used to treat coughs and congestion caused by the common cold, bronchitis, and other breathing illnesses. This product is usually not used for ongoing cough from smoking or long-term breathing problems (such as chronic bronchitis, emphysema) unless directed by your doctor. Guaifenesin is an expectorant. It works by thinning and loosening mucus in the airways, clearing congestion, and making breathing easier.

If you are self-treating with this medication, it is important to read the package instructions carefully before you start using this product to be sure it is right for you. (See also Precautions section.)

Cough-and-cold products have not been shown to be safe or effective in children younger than 6 years. Do not use this product to treat cold symptoms in children younger than 6 years unless specifically directed by the doctor. Some products (such as long-acting tablets/capsules) are not recommended for use in children younger than 12 years. Ask your doctor or pharmacist for more details about using your product safely.

These products do not cure or shorten the length of the common cold. To decrease the risk for side effects, carefully follow all dosage directions. Do not give other cough-and-cold medication that might contain the same or similar ingredients (see also Drug Interactions section). Ask the doctor or pharmacist about other ways to relieve cough and cold symptoms (such as drinking enough fluids, using a humidifier or saline nose drops/spray).

How to Use This Medication

Take this medication by mouth with or without food, as directed by your doctor, usually every 4 hours. If you are self-treating, follow all directions on the product package. If you have any questions, ask your doctor or pharmacist.

Guaifenesin may have a bitter taste. Do not split the tablets unless they have a score line and your doctor or pharmacist tells you to do so. Swallow the whole or split tablet without crushing or chewing.

If you are using the liquid form of this medication, carefully measure the dose using a special measuring device/spoon. Do not use a household spoon because you may not get the correct dose.

For powder packets, empty the entire contents of the packet onto the tongue and swallow. To prevent a bitter taste, do not chew.

Dosage is based on your age, medical condition, and response to treatment. Do not take more than 6 doses in a day. Do not increase your dose or take this drug more often than directed.

Drink plenty of fluids while taking this medication. Fluids will help to break up mucus and clear congestion.

Tell your doctor if your cough is accompanied by a headache that doesn't go away, fever, severe sore throat, rash, or if it lasts, returns, or gets worse after 7 days. These may be signs of a serious medical problem. Get medical help right away if you think you may have a serious medical problem.

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RxAnswers™ is a copyrighted combined product from TraceGains and First DataBank, Inc.

Drug information is selected from data included with permission and copyrighted by First DataBank, Inc. This is a summary and does not contain all possible information about this product. For complete information about this product or your specific health needs, ask your healthcare professional. Always seek the advice of your healthcare professional if you have any questions about this product or your medical condition. This information is not intended as individual medical advice and does not substitute for the knowledge and judgment of your healthcare professional. This information does not contain any assurances that this product is safe, effective or appropriate for you.

This information is intended only for residents of the United States. Products sold under the same brand names in other countries may contain different ingredients.

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Information expires December 2025.