Cetirizine is an antihistamine that is available only by prescription, according to MedlinePlus. Cetirizine is used to temporally reduce symptoms associated with hay fever and allergies caused by exposure to substances like molds, pet dander and dust mites. Some of the common symptoms that cetirizine helps to alleviate are watery eyes, runny nose, itchy nose and sneezing.
Cetirizine is normally taken once per day and comes in chewable tablet, extended release and regular tablet forms, according to MedlinePlus. This medication should not be used to eliminate hives that are not itching or those that are not blistered or bruised. The potential side effects associated with Cetirizine use are vomiting, drowsiness, dry mouth, diarrhea, fatigue and stomach pain.