Demerol is an opioid pain medication. An opioid is sometimes called a narcotic. Demerol is a strong prescription pain medicine that is used to manage the relief of short-term pain when other pain treatments, such as non-opioid pain medicines, do not treat your pain well enough or you cannot tolerate it. Careless use of Demerol can put you at risk of overdose and death. Even if you take your dose correctly as prescribed, you are at risk for opioid addiction, abuse, and misuse that can lead to death.