Codeine phosphate is a opioid analgesic medication used for the treatment of mild to moderate pain. Codeine is often used when relief is not provided by other pain killers such as ibuprofen or paracetamol. Codeine is a prescription pain medication used to treat mild to moderate pain. It comes in tablet form and as the main ingredient in prescription-grade cough suppressants. Tylenol 3, another popular pain reliever, is codeine combined with acetaminophen. Codeine is an opiate (sometimes called a narcotic)