Analgesic

An analgesic (colloquially known as painkiller) is any member of the diverse group of drugs used to relieve pain and to achieve analgesia (literally, "absence of pain"). Analgesic drugs act in various ways on the peripheral and central nervous system; they include paracetamol (acetaminophen), the nonsteroidal anti-inflammatory drugs (NSAIDs) such as the salicylates, narcotic drugs such as morphine, synthetic drugs with narcotic properties such as tramadol, and various others. Some other classes of drugs not normally considered analgesics are used to treat neuropathic pain syndromes; these include tricyclic antidepressants and anticonvulsants.

Reference

• Cancer pain relief and palliative care. Report of a WHO expert committee . Geneva, Switzerland: World Health Organization; 1990. pp. 1-75.