What is Demerol (Meperidine)? Demerol is the brand name of the prescription drug meperidine. The drug is used to treat moderate-to-severe pain, help put people to sleep before an operation, and provide pain relief after childbirth. Demerol is classified as a Schedule II (C-II) controlled substance. Demerol belongs to a class of pain medications called opioid analgesics, which work by binding to receptors on the surface of cells where opium normally binds, and stopping the body from sending pain signals to the brain.