The doctor prescribed me alegra, what is that?

Antihistamine: It's an allergy medication. It's spelled allegra (fexofenadine).

Antihistamine.: Allegra is second generation class of antihistamines. In other words, it is like a non-drowsy version of Benadryl, (diphenhydramine) which belongs to first generation antihistamine class. It is typically prescribed for seasonal allergies and various other allergic symptoms.