Does hydrocodone and chlorpheniram have the same chemical in them ## The answer to your question is no. Hydrocodone and Chlorpheniramine have completely different chemical structures and are prescribed for different purposes as individual medications. There is however a liquid combination of Chlorpheniramine + Hydrocodone that is marketed as a narcotic antitussive (cough suppressant) and antihistamine combination. The antitussive (codeine) works by suppressing the cough center in the brain. The antihistamine (promethazine) works by blocking the action of histamine, which reduces the symptoms of an allergic reaction such as itch, watery eyes and runny nose. Learn More: Hydrocodone Details Chlorpheniramine Details I hope this info helps! ## The antitussive (hydrocodone) works by suppressi...