Mucinex (guaifenesin) – by mouth

What is Mucinex?

mucus (Guaifenesin) is an over-the-counter (OTC) medication used to help relieve chest congestion caused by a cold or flu.

Mucinex belongs to a group of medicines called expectorants. Expectorants can thin the mucus in the lungs, making it easier to cough up phlegm.

Mucinex is available in several different over-the-counter formulations, including tablets, liquids, and dissolving granules. Some OTC cough and cold combination products also contain guaifenesin as an ingredient.

Drug Facts

Generic Name: Guaifenesin

Brand Name: Mucinex

Drug Availability: Over-the-Counter Drugs

Treatment classification: expectorant

Generally available: yes

Controlled Substances: Not applicable

Route of Administration: Oral

Active ingredient: Guaifenesin

Dosage form: tablet, extended-release tablet, solution, syrup, liquid, sachet

What is Mucinex used for?

The U.S. Food and Drug Administration (FDA) approves Mucinex to help loosen mucus (phlegm) and thin lung secretions, making it easier to cough up mucus and clear your lungs.

Mucinex is often used to improve symptoms of the common cold and other acute lung infections, but it will not treat a cold or help you recover faster.

How to take Mucinex

Mucinex is available in many different formulations, including extended-release (ER) tablets, liquids, and dissolving granules. Be sure to follow the directions on the package carefully to ensure you take the correct amount.

Guaifenesin is found in many cough and cold combination products. Always check the active ingredient list for all medicines you are taking to make sure guaifenesin is not present in more than one product.

You can take Mucinex with or without food, but if it causes stomach upset, taking it with food can help. Mucinex tablets should be taken with a full glass of water. Staying hydrated helps all Mucinex products work. In general, aim to drink at least eight 8-ounce glasses of water. Try to stick to decaffeinated beverages.

If you are using Mucinex ER tablets, swallow them whole without crushing, chewing, or breaking them.

If you are using dissolving granules, pour the packet on the tongue and swallow. Try not to chew the granules to avoid an unpleasant taste.


You can store Mucinex at room temperature. Keep Mucinex and all your medicines in a safe place away from children and pets.

Off-label use

Your healthcare provider may prescribe Mucinex to help treat conditions that this product cannot treat, including lung conditions such as chronic bronchitis. If you have chronic lung disease, use Mucinex only as recommended by your provider.

How long does it take for Mucinex to work?

Mucinex should start working the first day you start using it. Tell your healthcare provider if your symptoms do not improve within 7 days, or if your high fever, rash, or headache does not go away.

What are the side effects of Mucinex?

This is not a complete list of side effects, other side effects may occur. A medical professional can advise you about side effects. If you experience other effects, please contact your pharmacist or medical professional. You can report side effects to the FDA at or at 800-FDA-1088.

common side effects

Most people will not experience any side effects while taking Mucinex, but tell your healthcare provider if you experience any reactions, including:

  • headache
  • nausea
  • Vomit

serious side effects

Rarely, Mucinex can cause serious side effects. Call your healthcare provider right away if you develop any severe symptoms. If you think you have a life-threatening reaction, please call 911.

Mucinex can cause allergic reactions, which can sometimes be serious. Contact your provider immediately if you:

  • measles
  • Itchy, red, swollen, blistered, or peeling skin
  • rash
  • swelling of the mouth, face, lips, tongue, or throat
  • tightness in the chest or throat
  • Difficulty breathing, speaking, or swallowing
  • unusual hoarseness
  • respite

report side effects

Mucinex may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience serious side effects, you or your provider can send a report to the FDA’s MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

(800) 332-1088

Dosage: How much Mucinex should I take?

Drug content provided and reviewed

IBM Micromedicine®

The dose of this medicine will vary for different patients. Follow your doctor’s order or directions on the label. The information below includes only the average dose of this medicine. If your dose is different, do not change it unless your doctor tells you to.

The amount of medicine you take depends on the strength of the medicine. Also, the doses you take each day, the time allowed between doses, and the length of time you take the medication depend on the medical problem for which you are using the medication.

  • For conventional (short-acting) oral dosage forms (capsules, oral solutions, syrups or tablets):

    • For cough:

      • Adults – 200 to 400 milligrams (mg) every four hours.
      • Children 6 to 12 years – 100 to 200 mg every four hours.
      • Children 4 to 6 years – 50 to 100 mg every four hours.
      • Children and infants under 4 years – not recommended.
  • For long-acting oral dosage forms (sustained-release capsules or tablets):

    • For cough:

      • Adults – 600 to 1200 mg every twelve hours.
      • Children 6 to 12 years – 600 mg every 12 hours.
      • Children 4 to 6 years – 300 mg every 12 hours.
      • Children and infants under 4 years – not recommended.


Cough and cold combination products, including those containing guaifenesin, the active ingredient in Mucinex, can cause severe reactions and death in young children. Do not use these products in children under the age of 4.

For children over 4 years old, be sure to choose a children’s product that is appropriate for the child’s age (this information will be on the packaging). Read the directions carefully to make sure the correct dose is given based on your child’s age and weight. Never use adult products on children. If you have any questions about choosing a product or how much to give, ask your pediatrician or pharmacist.

missed dose

Mucinex is usually taken as needed, which means only if you have symptoms. If your healthcare provider tells you to take Mucinex regularly, take your missed dose as soon as you remember. If it’s almost time for your next dose, skip the missed dose and resume your normal dose schedule. Do not double or take extra Mucinex.

Overdose: What will happen if I take too much Mucinex?

There is limited information on the effects of an overdose of Mucinex, but it is not expected to cause serious symptoms. High doses of Mucinex may cause nausea and vomiting. Long-term use of high doses of Mucinex can also cause kidney stones.

What will happen if I overdose on Mucinex?

If you think you or someone else may have overdose on Mucinex, call your healthcare provider or poison control center (800-222-1222).

If someone passes out or is not breathing after taking Mucinex, call 911 right away.



Drug content provided and reviewed

IBM Micromedicine®

Talk to your doctor if your cough does not improve after 7 days, or if you have a fever, rash, persistent headache, or sore throat from coughing. These signs may mean you have other medical problems.

Why should I not take Mucinex?

Do not take Mucinex if you are allergic to guaifenesin or any other ingredient contained in the combination product. Always check the active ingredient list on the package to make sure the product does not contain the medicine you are allergic to.

Do not use these products in children under the age of 4.

What other drugs interact with Mucinex?

Mucinex may interact with other medicines you take. Always keep an up-to-date list of all medications, including OTC products, and share this information with your healthcare provider if it changes.

Some liquid forms of Mucinex contain alcohol. Avoid using these products with the following medicines, as unpleasant or even serious reactions may occur:

  • Antabuse (disulfiram)
  • Solosec (Secnidazole)

This is not a comprehensive list of all drugs that may interact with Mucinex. Be sure to ask your provider before starting anything new.

Frequently Asked Questions

  • What is Mucinex for?

    Mucinex is used to improve chest congestion caused by colds and acute lung infections.

  • How does Mucinex work?

    Mucinex is an expectorant that works by thinning lung secretions and loosening mucus (phlegm). This makes it easier for you to cough up mucus and clear your lungs.

  • When should you see your healthcare provider?

    Call your provider if your symptoms do not improve within 7 days, or if your high fever, rash, or headache does not go away. Do not use Mucinex for chronic lung disease (such as asthma or chronic obstructive pulmonary disease or COPD) unless recommended by your provider.

How can I stay healthy while taking Mucinex?

If you find yourself scouring drugstore shelves for something to ease cold symptoms, Mucinex may be a product that can help. Remember, Mucinex will not treat your cold or help you get better faster. Getting enough rest and staying hydrated is key.

Other remedies, such as using a humidifier or saline nasal rinse, can also help relieve congestion symptoms.

If you still can’t feel yourself after 7 days, or if your high fever, rash, or headache doesn’t go away, be sure to see your healthcare provider. These may be symptoms of another disease that needs treatment.

Medical Disclaimer

VigorTip Health’s drug information is for educational purposes only and is not a substitute for medical advice, diagnosis or treatment by a healthcare professional. Consult your doctor before taking any new medicines. IBM Watson Micromedex provides some drug content as shown on the page.