Codeine is a medication that falls into the opioid class of drugs. It is often used to relieve mild to moderate pain and can also be found in some over-the-counter cough medicines for its cough-suppressing properties. Codeine works by binding to opioid receptors in the brain and spinal cord, thereby reducing the perception of pain and, in the case of cough, suppressing the urge to cough.

It's essential to use codeine as prescribed by a healthcare provider because it can be habit-forming and has the potential for misuse. Like other opioids, codeine can cause side effects such as drowsiness, constipation, and respiratory depression (slowed breathing) when taken in excessive amounts or not as directed.