Guaifenesin is used to relieve chest congestion. Guaifenesin may help control symptoms but does not treat the cause of symptoms or speed recovery. Guaifenesin is in a class of medications called expectorants. It works by thinning the mucus in the air passages to make it easier to cough up the mucus and clear the airways.

Guaifenesin comes as a tablet, a capsule, an extended-release (long-acting) tablet, dissolving granules, and a syrup (liquid) to take by mouth. The tablets, capsules, dissolving granules, and syrup are usually taken with or without food every 4 hours as needed. The extended-release tablet is usually taken with or without food every 12 hours. Follow the directions on the package or on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take guaifenesin exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Guaifenesin comes alone and in combination with antihistamines, cough suppressants, and decongestants. Ask your doctor or pharmacist for advice on which product is best for your symptoms. Check nonprescription cough and cold product labels carefully before using two or more products at the same time. These products may contain the same active ingredient(s) and taking them together could cause you to receive an overdose. This is especially important if you will be giving cough and cold medications to a child.

Nonprescription cough and cold combination products, including products that contain guaifenesin, can cause serious side effects or death in young children. Do not give these products to children younger than 4 years of age. If you give these products to children 4 to 11 years of age, use caution and follow the package directions carefully.

If you are giving guaifenesin or a combination product that contains guaifenesin to a child, read the package label carefully to be sure that it is the right product for a child of that age. Do not give guaifenesin products that are made for adults to children.

Before you give a guaifenesin product to a child, check the package label to find out how much medication the child should receive. Give the dose that matches the child’s age on the chart. Ask the child’s doctor if you don’t know how much medication to give the child.

If you are taking the liquid, do not use a household spoon to measure your dose. Use the measuring spoon or cup that came with the medication or use a spoon made especially for measuring medication.

Swallow the extended-release tablets whole with a full glass of water. Do not break, crush, or chew them.

If you are taking the dissolving granules, empty the entire contents of the packet onto your tongue and swallow.

If your symptoms do not improve within 7 days or if you also have a high fever, a rash, or a headache that does not go away, call your doctor.

This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.

Before taking guaifenesin,

• Tell your doctor and pharmacist if you are allergic to guaifenesin, any other medications, or any of the ingredients in the guaifenesin product you plan to take. Check the package label for a list of the ingredients.
• Tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, nutritional supplements, and herbal products you are taking or plan to take.
• Tell your doctor if you smoke and if you have or have ever had a cough that occurs with a large amount of phlegm (mucus) or if you have or have ever had a breathing problem such as asthma, emphysema, or chronic bronchitis. If you will be taking the dissolving granules, tell your doctor if you are on a low magnesium diet or if you have kidney disease.
• Tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking guaifenesin, call your doctor.
• If you have phenylketonuria (PKU, a inherited condition in which a special diet must be followed to prevent damage to your brain that can cause severe intellectual disability), you should know that the dissolving granules may be sweetened with aspartame, a source of phenylalanine.

Drink plenty of fluids while you are taking this medication.

Unless your doctor tells you otherwise, continue your normal diet.

Guaifenesin is usually taken as needed. If your doctor has told you to take guaifenesin regularly, take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

Guaifenesin may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• Headache
• Nausea
• Vomiting

Guaifenesin may cause other side effects. Call your doctor if you have any unusual problems while you are taking this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration’s (FDA) MedWatch Adverse Event Reporting program online (http://www.fda.gov/Safety/MedWatch) or by phone (1-800-332-1088).

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom).

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA’s Safe Disposal of Medicines website (http://goo.gl/c4Rm4p) for more information if you do not have access to a take-back program.

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach. http://www.upandaway.org

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at https://www.poisonhelp.org/help. If the victim has collapsed, had a seizure, has trouble breathing, or can’t be awakened, immediately call emergency services at 911.

Ask your pharmacist any questions you have about guaifenesin.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.