Cetirizine is a second-generation antihistamine that reduces the natural chemical histamine in the body. Histamine can produce symptoms of sneezing, itching, watery eyes, and runny nose. Cetirizine is used to treat cold or allergy symptoms such as sneezing, itching, watery eyes, or runny nose. Cetirizine is also used to treat an allergic reaction, itching and swelling caused by chronic urticaria (hives) and minimizes or eliminates the symptoms of perennial allergic rhinitis, seasonal allergic rhinitis, chronic idiopathic urticaria, allergic asthma, physical urticaria, and atopic dermatitis.