Levocetirizine is used to relieve the symptoms of hay fever and hives of the skin. It is an antihistamine that works by preventing the effects of a substance called histamine, which is produced by the body. Histamine can cause itching, sneezing, runny nose, and watery eyes. It can also close up the bronchial tubes (air passages of the lungs) and make breathing difficult. Histamine can also cause some persons to have hives, with severe itching of the skin.