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 ...

As with other drugs, cetirizine can cause side effects, such as drowsiness and sore throat. If you are not able to tolerate side effects from cetirizine, talk with your doctor or pharmacist.