Diarrhea and coughing have also been observed in children. Cetirizine, the active ingredient of Zyrtec, is a second-generation antihistamine that blocks the action of histamine (a product of the ...

The active ingredient in Xyzal (levocetirizine) is a form of cetirizine (the active ingredient in Zyrtec). Xyzal offers several advantages for people dealing with allergies: It provides fast ...