How Does Mucinex Work?

Mucinex is the brand name of an over-the-counter medication for relieving chest congestion. The active ingredient is guaifenesin, an expectorant. Mucinex comes in a variety of formulations containing guaifenesin combined with other ingredients, such as cough suppressants, antihistamines and fever reducers. It is sold as a capsule, a time-released tablet or a liquid.

Is This an Emergency?

If you are experiencing serious medical symptoms, seek emergency treatment immediately.

Actions in the Body

Chest congestion occurs when mucus thickens and clogs air passages. Guaifenesin is an expectorant, which means it thins mucus and makes it is easier to cough up. In a January 2006 article published in the journal "Chest," Donald Bosler, Ph.D., on behalf of the American College of Chest Physicians, reports the effectiveness of guaifenesin for the treating cough is not firmly established. Although Mucinex may help relieve the symptoms of chest congestion in some people, it does not treat the underlying illness.

Side Effects and Cautions

Mucinex can cause a headache, nausea, vomiting or other side effects. Consult a doctor about any unusual symptoms that occur while taking Mucinex.

Talk to a doctor before giving Mucinex or any over-the-counter cough medicine to a child under 6. The U.S. Food and Drug Administration recommends that children under 4 years old never be given over-the-counter cough and cold remedies 5.

Use care in combining Mucinex with similar over-the-counter medications, such as cough syrups or allergy tablets. Read the ingredients lists carefully to avoid taking an overdose of any of the ingredients.

If a cough lasts more than a week or is accompanied by fever, rash or persistent headache, stop taking Mucinex and consult a doctor.