Codeine is an opioid found naturally in Papaver somniferum, the opium poppy. It’s somewhat misleading to call it an opioid since codeine primarily functions as a prodrug, offering little of its own activity. Morphine seems to be its primary active metabolite.

The drug is typically a controlled substance, yet it may also be available over-the-counter (OTC) in certain combinations.

Its name comes from the Greek word “kodeia,” which means “poppy head.”

Medically, codeine is used as an analgesic, antitussive, and antidiarrheal. It’s also taken recreationally, often at higher doses.