Promethazine-DM is the generic form of Phenergan-DM. It is a prescription medication available in syrup form that contains promethazine and dextromethorphan. It is used to prevent coughing and a runny nose.
Promethazine is an antihistamine that lessens coughing by decreasing postnasal drip, the secretions that drain from the sinuses into the throat.
Dextromethorphan is a medication that suppresses the cough reflex.
Dextromethorphan is a synthetic derivative of codeine, but it does not have the potential for abuse and dependence.
The most common side effect of Promethazine-DM is drowsiness. Promethazine-DM can also cause dry mouth and dry eyes.
Dextromethorphan should not be taken with antidepressants in the monoamine oxidase inhibitor (MAOI) or selective serotonin reuptake inhibitor (SSRI) families due to the risk of a rare but serious side effect known as serotonin syndrome.
Promethazine can sometimes cause so much drowsiness that it slows breathing to a dangerous extent. Promethazine should be used with caution in children and should not be given to children under the age of 2.