Promethazine is used to relieve or prevent the symptoms of hay fever, allergic conjunctivitis (inflammation of the eye), and other types of allergy or allergic reactions. It 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 sometimes close up the bronchial tubes (air passages of the lungs) and make breathing difficult .
Promethazine is also used to prevent and control motion sickness, nausea, vomiting, and dizziness. In addition, it may be used to help people go to sleep and control their pain or anxiety before or after surgery or other procedures
