Morphine , widely used to relieve severe pain, is sometimes abused, often by medical professionals. Codeine , like morphine, is a natural ingredient of opium, although less potent. It is found in prescription cough medicines and pain relievers and is favored by some abusers. Methadone, a synthetic used mainly in the treatment of heroin addiction, is often abused and responsible for a number of overdose deaths. Fentanyl is a powerful synthetic used for severe pain and as a surgical anesthetic.
Abuse is very dangerous.
Narcotics affect many organs through the autonomic nervous system, which controls such body functions as circulation, respiration, and digestion. They cause blood vessels to relax and heartbeat to slow, lowering blood pressure. They slow and weaken contraction of muscles that control breathing and constrict intestinal muscles, slowing digestion. Narcotics may produce drowsiness, grogginess, and mental confusion. As do most drugs of abuse, narcotics induce euphoria.