What You Need to Know About Mucinex

Young woman coughing
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Mucinex is an over the counter cough medication that helps to break up chest congestion. It is an expectorant, which means it thins out congestion so that it can drain and be expelled more easily when you cough. It does not stop or suppress a cough, it simply makes it more effective. Mucinex lasts for 12 hours.

Active Ingredients (in each extended release tablet)

Guaifenesin 600mg (expectorant)


Adults children 12 years and older - One or two tablets every 12 hours. Do not exceed 4 tablets in 24 hours.

Not for children under 12 years of age. There are other Mucinex products available for children under 12.


Mucinex helps loosen and thin mucus in the chest so that it can be expelled more easily when coughing.

Side Effects 

  • Dizziness
  • Headache
  • Upset stomach

Rare but serious side effects that should be reported to your doctor immediately:

  • Signs of allergic reaction including skin rash, itching or hives
  • Swelling of face, lips or tongue
  • Difficulty breathing (call 911)
  • Warnings

    Do not use this medication in children under 12 years old.
    • There are Mucinex products available for younger children in different strengths and formulations.
      • Ask a Doctor Before Use

        • If you have a chronic cough that is caused by asthma, smoking or emphysema
      • If you have a cough that produces a lot of mucous
      • If you are pregnant or breastfeeding
      • Stop Use and Ask a Doctor If

        • Cough worsens or lasts more than 7 days
        • Cough occurs with fever, headache or rash that won't go away
        • Source:
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    Article Sources

    • "Mucinex Product Labeling (Drug Facts)." Mucinex 2008. Reckitt Beckiser Inc. 27 Jul 09.