|Short description Overview and Benefits   Promethazine is a drug used to treat allergies. It treats such symptoms as itching, itchy or watery eyes, sneezing, runny nose, skin rashes and hives. The drug may also be prescribed to prevent motion sickness and to treat nausea and vomiting as well as pain after a surgery. The medicine can also be used as a sleeping aid or a sedative.   Promethazine belongs to a group of drugs known as phenothiazines. In its working, the drug changes the effects of chemicals in the brain. It works basically as an antihistamine blocking the effects of histamine in the brain.   It is important to note that Promethazine cannot be used to treat the symptoms of pneumonia, asthma and other infections in the lower respiratory tract.