Demerol is the trade name of meperidine, a synthetic opioid analgesic that is used to treat moderate to severe pain. Demerol is a prescription medication that functions in a manner similar to morphine. Though it was once mistakenly believed that Demerol is less addictive than morphine is, that has proven not to be the case. Because of Demerol’s high risk for dependence, and due to the potential toxicity when the drug is used for an extended period of time, this medication is usually prescribed only for short-term use, such as to relieve acute pain in the immediate aftermath of surgery. Demerol may be taken orally as a tablet or syrup; it may also be administered via intramuscular injection.