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Guaifenesin

Generic name: guaifenesin [ gwye-FEN-e-sin ]
Brand names: Mucinex, Robitussin Mucus + Chest Congestion, Triaminic Chest Congestion, Tussin Expectorant, Xpect, Organidin NR, Bidex 400
Drug class: Expectorants

Medically reviewed by Melisa Puckey, BPharm. Last updated on May 6, 2024.

What is guaifenesin?

Guaifenesin is an ingredient in cough and cold medicines that is used to help clear mucus or phlegm from your chest when you have had a cold or flu. Guaifenesin works by making your mucus thinner and easier to cough up, which helps clear chest congestion. Guaifenesin is available as an over-the-counter (OTC) medicine and also available on prescription.

Guaifenesin is not FDA approved for treatment of fibromyalgia but some people take it off-label for this condition.  In clinical studies guaifenesin has not shown to be effective for fibromyalgia.

Warnings

You should not use this medicine if you are allergic to guaifenesin.

Use this medicine exactly as directed on the label, or as prescribed by your doctor. Do not use it in larger amounts or for longer than recommended.

Guaifenesin is commonly found as part of over-the-counter combination medications for cold and cough. Read labels or ask a doctor or pharmacist before using any other cold, or cough medicine when taking guaifenesin.

Always ask a doctor before giving a cough or cold medicine to a child. Death can occur from the misuse of cough and cold medicines in very young children.

Drink extra fluids to help loosen the congestion and lubricate your throat while you are taking this medication. This medication may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert.

Before taking this medicine

Ask a doctor or pharmacist if it is safe for you to use this medicine if you have other medical conditions, such as liver disease, kidney disease, or phenylketonuria (PKU).

It is not known whether guaifenesin will harm an unborn baby. Ask a doctor before using this medicine if you are pregnant.

It is not known whether guaifenesin passes into breast milk or if it could harm a nursing baby. Ask a doctor before using this medicine if you are breast-feeding a baby.

Do not give this medicine to a child without medical advice.

Guaifenesin pregnancy and breastfeeding warnings (more detail)

How should I take guaifenesin?

Use guaifenesin exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended. Cough medicine is usually taken only for a short time until your symptoms clear up.

Take guaifenesin with food if it upsets your stomach.

Measure liquid medicine with the dosing syringe provided, or with a special dose-measuring spoon or medicine cup. If you do not have a dose-measuring device, ask your pharmacist for one.

Do not crush, chew, break, or open a controlled-release, delayed-release, or extended-release tablet or capsule. Swallow it whole. Breaking or opening the pill may cause too much of the drug to be released at one time.

Drink extra fluids to help loosen the congestion and lubricate your throat while you are taking this medication.

Store at room temperature away from moisture, heat, and light.

Dosing information

Usual Adult Dose for Cough:

Immediate release formulation: 200 to 400 mg orally every 4 hours as needed, not to exceed 2.4 g/day

Sustained release formulation: 600 to 1200 mg orally every 12 hours, not to exceed 2.4 g/day

Usual Pediatric Dose for Cough:

Immediate release formulation:

less than 2 years: 12 mg/kg/day orally in 6 divided doses

2 to 5 years: 50 to 100 mg orally every 4 hours as needed, not to exceed 600 mg/day

6 to 11 years: 100 to 200 mg orally every 4 hours as needed, not to exceed 1.2 g/day

12 years or older: 200 to 400 mg orally every 4 hours as needed, not to exceed 2.4 g/day

Sustained release formulation:

2 to 5 years: 300 mg orally every 12 hours, not to exceed 600 mg/day

6 to 11 years: 600 mg orally every 12 hours, not to exceed 1.2 g/day

12 years or older: 600 to 1200 mg orally every 12 hours, not to exceed 2.4 g/day

Detailed Guaifenesin dosage information

albuterol, amoxicillin, doxycycline, ciprofloxacin, azithromycin, benzonatate, ceftriaxone, diphenhydramine, Augmentin, guaifenesin

What happens if I miss a dose?

Since cough or cold medicine is taken when needed, you may not be on a dosing schedule. If you are taking the medication regularly, take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What to avoid

This medication may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert.

Ask a doctor or pharmacist before using any other cold, or cough medicine. Many combination medicines contain guaifenesin. Taking certain products together can cause you to get too much of a certain drug. Check the label to see if a medicine contains guaifenesin.

Guaifenesin side effects

Get emergency medical help if you have signs of an allergic reaction to guaifenesin: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Common guaifenesin side effects may include:

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Guaifenesin side effects (more detail)

What other drugs will affect guaifenesin ?

Other drugs may interact with guaifenesin, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using.

Does guaifenesin interact with my other drugs?

Enter medications to view a detailed interaction report using our Drug Interaction Checker.

Popular FAQ

Does Mucinex help you get pregnant?

Some research suggests that Mucinex may help increase fertility by keeping the cervical mucus thin around the time of ovulation, which ensures sperm can travel freely through the cervix and helps with sperm survival. An increase in fertility can help increase your chances of becoming pregnant. Women with hostile mucus as the only cause of their infertility are the ones most likely to benefit from guaifenesin treatment. Continue reading

Does Mucinex help with Covid?

Mucinex products do not help to prevent or treat the COVID-19 virus itself, but might help relieve some of the symptoms of COVID, like chest congestion, cough, or headache. Select a product that targets only the symptoms you have. Continue reading

More FAQ

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References

  1. Mayo Clinic: Guaifenesin (Oral Route)

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use guaifenesin only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer

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