Codeine is a weak narcotic pain reliever and cough suppressant similar to morphine and hydrocodone. In fact, a small amount of codeine is converted to morphine in the body. The precise mechanism of action of codeine is not known; however, like morphine, codeine binds to receptors in the brain (opioid receptors) that are important for transmitting the sensation of pain throughout the body and brain. Codeine increases tolerance to pain, decreasing discomfort, but the pain still is apparent to the patient. In addition to reducing pain, codeine also causes sedation drowsiness and depresses breathing. Codeine frequently is combined with acetaminophen (Tylenol) or aspirin for more effective pain relief. Buy Codeine pills Online.