Question: what is the difference between zyrtec d and allegra d?
Answer: Allegra-D (fexofenadine / pseudoephedrine) is a combination allergy medicine that's useful if you have congestion and runny nose. The antihistamine (Cetirizine) in Zyrtec D (Cetirizine / Pseudoephedrine) causes less drowsiness than other medications like Benadryl.