Levocetirizine is a second-generation antihistamine used to relieve symptoms associated with seasonal allergic rhinitis (hay fever), perennial allergic rhinitis, and chronic idiopathic urticaria (hives). It works by blocking histamine H1 receptors, which helps reduce allergy symptoms such as sneezing, runny nose, itchy eyes, and skin rashes. Compared to older antihistamines, levocetirizine is less likely to cause drowsiness and typically begins working within an hour of ingestion, providing 24-hour symptom relief with once-daily dosing.