Promethazine is in a group of drugs called phenothiazines (FEEN-oh-THYE-a-zeens). It works by changing the actions of chemicals in your brain. Promethazine also acts as an antihistamine. It blocks the effects of the naturally occurring chemical histamine in your body. Promethazine is used to treat allergy symptoms such as itching, runny nose, sneezing, itchy or watery eyes, hives, and itchy skin rashes. Promethazine also prevents motion sickness, and treats nausea and vomiting or pain after surgery. It is also used as a sedative or sleep aid. Promethazine is not for use in treating symptoms of asthma, pneumonia, or other lower respiratory tract infections. Promethazine may also be used for other purposes not listed in this medication guide.
As an antihistamine, Phenergan (Promethazine) is used to treat allergy symptoms such as a runny nose or itching from a rash. In addition to that, Phenergan may also be used to combat the occurrence of nausea and vomiting after a surgery. Phenergan works by blocking histamines that are created during an allergic reaction. The drug blocks out pain and nausea by altering natural substances such as acetylcholine.