Metamizole is a pyrazole that is antiipyrine substituted at C-4 by a methyl(sulfomethyl)amino group, the sodium salt of which, metamizole sodium, was widely used as a powerful analgesic and antipyretic, but withdrawn from many markets from the 1970s due to a risk of causing risk of causing agranulocytosis. It has a role as an antipyretic, an antirheumatic drug, a non-narcotic analgesic, a non-steroidal anti-inflammatory drug, a peripheral nervous system drug, a prodrug and a cyclooxygenase 3 inhibitor. It is a member of pyrazoles and an amino sulfonic acid. It derives from an antipyrine. It is a conjugate acid of a metamizole(1-).