Musinex Side Effects

Mucinex is a brand name for the medication guaifenesin, which people take to relieve coughing and chest congestion caused by colds, flu or allergies. An expectorant, Mucinex originally was available by prescription only, but now can be purchased over-the-counter. It is commonly misspelled Musinex. Several side effects are possible.

Common Side Effects

• The most common side effects when using Mucinex Cough Mini-Melt Granule Packets include dizziness, drowsiness and stomach upset.

Junior Strength Medicine

• Common side effects for children taking Mucinex Junior Strength Granules include nausea and vomiting.

Other Side Effects

• Other possible side effects with Mucinex medications include constipation or diarrhea, gas, headache and rash.

Too Much Medication

• Taking too much Mucinex can cause more obvious dizziness or drowsiness, as well as fatigue, weakness and a slow heartbeat.

Mucinex D

• Another type of Mucinex is called Mucinex D, which contains pseudoephedrine in addition to guaifenesin. Pseudoephedrine has other side effects, including a fast or pounding heartbeat, dizziness, anxiety, nervousness, restlessness and insomnia.