Promethazine/codeine is an inexpensive drug used as a cough suppressant, a decongestant, and an antihistamine. It helps to stop or reduce coughing and congestion. It is more popular than comparable drugs. Promethazine/codeine is only available as a generic drug; all brands have been discontinued. Generic promethazine/codeine is covered by most Medicare and insurance plans, but some pharmacy coupons and cash prices may be lower.