Reactions to Mucinex

Updated June 13, 2017

Mucinex is the over-the-counter brand name for guaifenesin. Mucinex is an expectorant that is used to relieve chest congestion by making it easier to cough up mucus. You may experience a few side effects when using Mucinex.


A less serious side effect of taking Mucinex is stomach upset. You may suffer from nausea or vomiting. Speak to your physician if you experience these symptoms.


A common side effect of Mucinex is headache, and you may also experience some dizziness. Talk to your doctor if these symptoms persist.


A rare and unusual reaction to Mucinex is skin irritation. Contact your physician if you begin to develop a rash.

Allergic Reaction

Signs of an allergic reaction to Mucinex are breathing difficulties, swelling of the lips, tongue and face, closing of the throat and hives. Stop taking Mucinex and seek immediate medical attention if you experience these symptoms.


Mucinex is not recommended for children under 12. Women who are pregnant or breast-feeding should consult their physician before taking Mucinex. Stop using Mucinex and contact your doctor if your coughing lasts more than seven days, if coughing comes back and you develop a rash, fever or persistent headache. Keep Mucinex out of reach of children. If overdose is suspected; contact the poison control centre and seek medical attention immediately.

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