Reviewed on 8/19/2021

What Is Guaifenesin and How Does It Work?

Guaifenesin is used to treat coughs and congestion caused by the common cold, bronchitis, and other breathing illnesses. Guaifenesin 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 guaifenesin, it is important to read the package instructions carefully before you start using this product to be sure it is right for you.
  • Cough-and-cold products have not been shown to be safe or effective in children younger than 6 years. Therefore, do not use guaifenesin 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.
  • Products that include guaifenesin 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).
  • Guaifenesin is available under the following different brand names: Mucinex, Bidex 400, and Organidin NR.

What Are Dosages of Guaifenesin?

Dosages of Guaifenesin:

Adult and Pediatric Dosage Forms & Strengths


  • 200 mg
  • 400 mg

Tablet, extended-release

  • 600 mg
  • 1200 mg

Oral syrup

  • 100 mg/5mL


  • 100 mg/5mL
  • 200 mg/5mL


  • 50 mg
  • 100 mg
Dosage Considerations – Should be Given as Follows: Cough


  • 100-400 mg orally every 4 hours; not to exceed 2.4 g/day


  • 1-2 tablets (600-1200 mg) orally every 12 hours; not to exceed 4 tablets/24 hours (2.4 g/day)


  • Children 6 months to 2 years: 25-50 mg every 4 hours; not to exceed 300 mg/day
  • Children 2-6 years: 50-100 mg orally every 4 hours; not to exceed 600 mg/day
  • Children 6-12 years: 100-200 mg orally every 4 hours; not to exceed 1.2 g/day
  • Children older than 12 years
    • 100-400 mg orally every 4 hours; not to exceed 2.4 g/day, OR
    • 1-2 extended-release tablets (600-1200 mg) orally every 12 hours; not to exceed 4 tablets/24 hours (2.4 g/day)
  • Swallow extended-release tablets whole; do not chew or crush


Which illness is known as a viral upper respiratory tract infection? See Answer

What Are Side Effects Associated with Using Guaifenesin?

Common side effects of guaifenesin include:

  • Dizziness
  • Drowsiness
  • Decreased uric acid levels
  • Stomach pain
  • Nausea
  • Vomiting
  • Headache
  • Rash

Postmarketing side effects of guaifenesin reported include:

This document does not contain all possible side effects and others may occur. Check with your physician for additional information about side effects.

What Other Drugs Interact with Guaifenesin?

If your doctor has directed you to use this medication for diabetes, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

  • Guaifenesin has no known severe, serious, moderate, or mild interactions with other drugs.

This document does not contain all possible interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist. Check with your physician if you have health questions or concerns.

What Are Warnings and Precautions for Guaifenesin?


This medication contains guaifenesin. Do not take Mucinex, Bidex 400, or Organidin NR if you are allergic to guaifenesin or any ingredients contained in this drug.


Hypersensitivity to guaifenesin

Effects of Drug Abuse


Short-Term Effects

See "What Are Side Effects Associated with Using Guaifenesin?"

Long-Term Effects

See "What Are Side Effects Associated with Using Guaifenesin?"


Often comes in combos; check brand name/other constituents.

Some products may contain phenylalanine.

When using self-medication in chronic or persistent coughs, notify the healthcare practitioner if no improvement within 7 days.

Pregnancy and Lactation

Use guaifenesin with caution during pregnancy if the benefits outweigh the risks. Animal studies show risk and human studies are not available, or neither animal nor human studies were done.

It is unknown if guaifenesin is excreted in breast milk; use caution if breastfeeding.


Cold and Flu: Finding Relief for Your Cough See Slideshow
Medscape. Guaifenesin.

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