Analgesic drugs are classified into three groups:
Nonopioid analgesic drugs include acetaminophen and nonsteroidal anti-inflammatory drugs or NSAIDs.
Opioid drugs, sometimes referred to as "narcotics", include natural substances such as morphine, and semi synthetic and synthetic substances. These substances relieve pain by binding to opioid receptors in the nervous system.
Coanalgesic medications are drugs that have a primary use other than pain relief, but also help produce analgesia for some painful conditions.