Guaiphenesin, also spelled guaifenesin, thins the mucus sitting in the airways so that coughing clears it more easily. It suits a chesty, productive cough and is the opposite of a cough suppressant.

What Guaiphenesin Is Used For

Chesty cough with thick phlegm
Cough during a cold, flu or bronchitis
An ingredient in combination cough syrups

Common Side Effects

Nausea
Stomach discomfort
Dizziness
Drowsiness in some combination products

Precautions

Drinking plenty of water does much of the thinning work, so fluids matter as much as the syrup. Read combination labels carefully, since many products mix an expectorant with a suppressant, which works against itself. See a doctor if the cough lasts more than two to three weeks, brings up blood, or comes with fever, breathlessness or chest pain.

This page is general information only. It is not a substitute for advice from your doctor or pharmacist, and it does not include dosage. Always follow the directions given to you and read the leaflet inside the pack.