Cetirizine is an antihistamine medication commonly used to relieve allergy symptoms such as sneezing, runny nose, and itchy eyes. It works by blocking the action of histamine, a substance in the body that causes allergic reactions. Cetirizine is often taken for conditions like hay fever and hives. This medication is available over-the-counter and is typically taken once daily. It is generally well-tolerated, but some people may experience side effects like drowsiness or dry mouth. Always consult a healthcare professional before starting any new medication, especially if you have existing health conditions or are taking other drugs.