Zyrtec 24 Hour Allergy Relief Antihistamine Tablets for powerful relief of your worst allergy symptoms. Allergy tablets start working at hour 1 & work twice as hard when you take it again the next day. This powerful antihistamine tablet contains 10 mg of cetirizine hydrochloride for allergy relief. Prescription-strength allergy medicine treats runny nose, sneezing, and itchy eyes, nose & throat. Get effective allergy relief from the #1 allergist-recommended brand among OTC oral antihistamines. Anti-allergy medicine provides powerful relief to help treat both indoor and outdoor allergies. HSA/FSA Eligible