Zyrtec, Generic Zyrtec, Cetirizine is an antihistamine.

Cetirizine blocks the actions of the naturally occurring chemical histamine in the body and less likely than some other antihistamines to cause side effects such as drowsiness and dizziness.

Cetirizine is used to treat the symptoms of allergies such as sneezing; runny nose; itching, tearing, and redness of the eyes; and hives.