CODEINE; PHENYLEPHRINE; PROMETHAZINE is a cough suppressant, a decongestant, and an antihistamine. It helps to stop or reduce coughing and congestion of colds or allergies. This medicine will not treat an infection. The lowest GoodRx price for the most common version of promethazine / codeine is around $3.49, 80% off the average retail price of $18.03.