Zyrtec is an antihistamine that reduces the effects of natural chemical histamine in the body. Histamine can produce symptoms of sneezing, itching, watery eyes, and runny nose. Zyrtec is used to treat cold or allergy symptoms such as sneezing, itching, watery eyes, or runny nose.
Zyrtec is also used to treat itching and swelling caused by chronic urticaria (hives). Zyrtec may also be used for purposes not listed in this medication guide.