It is safe to take cetirizine (the active ingredient in Zyrtec) and guaifenesin (the active ingredient in Mucinex) together. There is no interaction between them.

In fact, it is fairly common to take the combination as they each help to treat different symptoms.

Cetirizine, a 'second-generation' antihistamine, is effective for treating many of the symptoms we associate with allergies or colds, including:

  • Sneezing
  • Runny nose
  • Watery eyes
  • Itching
  • Redness

Guaifenesin is an expectorant, helping to clear chest congestion and thin mucus secretions.

Cetirizine and guaifenesin can have synergistic effects.

Cetirizine can help to 'dry' mucus secretions, due to the anticholinergic effects of the drug. This can aid in reducing or helping to expectorate thick mucus that feels as though it is 'stuck' in your chest and airway.

Guaifenesin is generally very well tolerated and has few side effects or interactions. Nausea, drowsiness, dizziness, and headache occur rarely at recommended doses of guaifenesin.

Cetirizine may cause drowsiness in some individuals, but this effect should not be exacerbated by the addition of guaifenesin.

Answer Summary

There is no interaction between guaifenesin and cetirizine. They are safe to take together.

  1. ClinicalKey: Guaifenesin Monograph. ClinicalKey
  2. ClinicalKey: Cetirizine Monograph. ClinicalKey