What are allegra and xyzal (levocetirizine) used for?

Allergies: Allegra and xyzal are two different types of antihistamines. They are called non sedating antihistamines as older antihistamines like Benadryl (diphenhydramine) cause drowsiness in some people. The entire class of medicines are used to treat allergies or allergic reactions.

Antihistamines: Both are oral antihistamines in the 2nd generation, which means they cause much less sedation.