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 prescribed for conditions like hay fever and hives. This medication is available over-the-counter and is typically taken once daily. It is known for causing less drowsiness compared to older antihistamines, making it a popular choice for those who need to remain alert. However, some individuals may still experience mild sedation as a side effect.