Foster And Thrive, All Day Allergy Cetirizine Hcl, 10 Mg, 300 TabsProduct Description All day allergy cetirizine HCL is an over the counter antihistamine medication designed to provide relief from allergy symptoms caused by seasonal or year round allergies. The active ingredient, cetirizine hydrochloride, is a second generation antihistamine that works by blocking the effects of histamine, a substance in the body that triggers allergy symptoms like sneezing, runny nose, and itching. Product Benefits Original