Generic Name: cetirizine (seh TEER ih zeen) Brand Names: Zyrtec What is cetirizine? Cetirizine is an antihistamine. Cetirizine blocks the actions of the naturally occurring chemical histamine in the body. Cetirizine is 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. Cetirizine may also be used for purposes other than those listed in this medication guide. Please consult your personal physician before you start taking any type of medication. You can find this at our Mexican pharmacy everyday low prices.