Pethidine, also known in the US as meperidine (brand name: Demerol), is classified as a prescription opioid pain medication (opioid analgesic), also called a narcotic. Pethidine is used for the relief of moderate to severe pain. It has fallen out of use in the US and some other countries because it is considered a high-alert drug due to a significant risk of dangerous side effects when used in error.