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Overview: Guaifenesin is used to help with chest congestion from a cold, the flu, and other illnesses. It is usually well tolerated. You can find guaifenesin in many over-the-counter (OTC) combination cough and cold medicines. Guaifenesin is available in several formulations including tablets, extended-release tablets, and a liquid.

Uses

What is guaifenesin used for?

Guaifenesin is commonly used to treat chest congestion caused by the common cold, flu, bronchitis, and other illnesses.

Guaifenesin may also be used for other conditions as determined by your health care provider.

Usual Dosing

  • Adults and children 12 years or older: 200 to 400 mg every 4 hours (liquid and oral tablets), 600 to 1200 mg every 12 hours (extended-release tablets). Do not take more than 2400 mg in 24 hours.
  • Children 6 to 11 years: 100 to 200 mg every 4 hours. Do not take more than 1200 mg in 24 hours.
  • Children 2 to 5 years: 50 to 100 mg every 4 hours. Do not take more than 600 mg in 24 hours.
  • Children less than 2 years: Do not use without talking to your health care provider.

How does guaifenesin work (mechanism of action)?

Guaifenesin is an expectorant. It helps decrease chest congestion by thinning and loosening mucus, making coughs more productive. This helps clear the mucus from your airways, making it easier to breathe.

How is guaifenesin supplied (dosage forms)?

Guaifenesin is available in Mucinex, Robitussin, Tussin, Diabetic Tussin, and other brand and generic products for children and adults. Some common formulations of guaifenesin products are listed below.

  • 200 mg, 400 mg oral tablets
  • 600 mg, 1200 mg extended-release oral tablets
  • 100 mg/5 mL, 200 mg/5 mL oral liquid

There are many OTC and prescription cough and cold products that contain guaifenesin alone or in combination with other ingredients. Always check the labels of all medicines you take. Ask your pharmacist if you are unsure if your other medicines also contain guaifenesin.

How should I store guaifenesin?

Guaifenesin should be stored at room temperature, between 68 F and 77 F (20 C and 25 C). It can be exposed to temperatures between 59 F and 86 F (15 C and 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place.

Side Effects

What are the most common side effects of guaifenesin?

Guaifenesin is usually well-tolerated and side effects are not common.

Contact your health care provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088 (800-332-1088). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of guaifenesin?

While less common, the most serious side effects of guaifenesin are described below, along with what to do if they happen.

Severe Allergic Reactions. Any medicine may cause an allergic reaction, which can be serious. Stop taking guaifenesin and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Warnings & Precautions

Who should not use guaifenesin?

Allergies to Ingredients. Do not take guaifenesin if you are allergic to it or any of the other ingredients in the product. Your pharmacist can tell you all of the ingredients in the specific guaifenesin products they stock.

What should I know about guaifenesin before using it?

Drink plenty of water while taking guaifenesin. This can help the effect of guaifenesin.

Stop using guaifenesin and contact your health care provider if your cough lasts longer than 7 days, your cough comes back, or you develop a fever, rash, or headache that does not go away. These can be signs of a more serious illness.

Keep guaifenesin out of the reach of children.

If you are taking a liquid form of guaifenesin, use an accurate measuring device to measure your dose. A household spoon is not an accurate measuring device and may cause you to take the wrong dose. Ask your pharmacist what measuring device to use.

Do not chew, cut, or crush guaifenesin extended-release tablets.

What should I tell my health care provider before using guaifenesin?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if guaifenesin is right for you.

In particular, make sure that you discuss any of the following.

Chronic Cough. Talk to your health care provider before taking guaifenesin if you have a chronic cough caused by conditions such as asthma, smoking, emphysema, or chronic bronchitis. 

Excess Mucus. Talk to your health care provider before taking guaifenesin if you have a cough with a lot of mucus.

Pregnancy. It is not known if or how guaifenesin could affect pregnancy or harm an unborn baby. Tell your health care provider if you are pregnant or plan to become pregnant. Your health care provider will let you know if you should take guaifenesin while you are pregnant or trying to get pregnant.

Breastfeeding. It is not known if guaifenesin passes into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed. Your health care provider will let you know if you should take guaifenesin while breastfeeding.

Interactions

Does guaifenesin interact with foods or drinks?

There are no known interactions between guaifenesin and foods or drinks.

It is unknown if drinking alcohol will affect guaifenesin.

Does guaifenesin interact with other medicines (drug interactions)?

There are no known interactions between guaifenesin and other medicines. Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much guaifenesin?

If you or someone else has used too much guaifenesin, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of guaifenesin?

Guaifenesin is meant to be used only when needed. Use it as directed on the label or as your health care provider recommends. Do not take double or extra doses.