Get 24-hour relief from allergy symptoms caused by ragweed, tree pollen, dust mites, pet dander hay fever and other upper respiratory allergies with Zyrtec Allergy Relief Medicine Tablets. With 10 milligrams of the antihistamine cetirizine hydrochloride per tablet, this prescription-strength allergy relief medicine provides 24 hours of relief from common symptoms of allergies including runny nose, sneezing, itchy, watery eyes, and itching of the nose or throat.