Demerol is the brand name under which the prescription drug, meperidine, is sold. This medication is used to assist in relieving average to extremely severe pain associated with many medical, surgical, obstetrical, and dental procedures. Prior to or during surgery or other procedures, it may be used in order to help put patients back to sleep and provide relief from pain after childbirth. Demerol is categorized as a Schedule II (C-II) controlled substance. It is affiliated to a class of drugs called opioid narcotic analgesics, which is similar to morphine. Sudden episodes of moderate to severe pain should be treated by Demerol and should not be used to treat long-term ongoing pain. It works to reduce pain by acting on the brain to increase brain tolerance. It tends to work swiftly and should not be used to treat chronic pain.