Codeine is a prescription medication which relieves mild to moderate pain. It was originally discovered as a naturally occurring constituent of opium. However, today's pharmaceutical-grade codeine is produced by methylating morphine. Codeine comes alone or combined with another painkiller such as Tylenol (acetaminophen). It is formulated into tablets, capsules or liquid to be taken orally. Codeine and codeine-combo preparations are usually taken every 4-6 hours. Since codeine can be habit forming, care must be taken to follow the doctor's instructions. Do not take a larger dose, or take it more frequently, or take it for longer than the doctor has prescribed.