Metamizole: reassessment of its therapeutic role.

The use of metamizole is controversial, as reflected in the very different national regulations affecting it. The striking disparities between policies for metamizole made us try to determine if there were reasons to ban, limit or liberalize its utilization. After reviewing the literature, it was concluded that metamizole should not be withdrawn from the countries where its use is still relatively free. However, metamizole causes life-threatening adverse events that are usually unpredictable and can only be prevented by better prescribing habits, so it is suggested that its use as a first-line agent should be restricted to the treatment of the pain of acute colic and circumstances in which parenteral administration of a non-narcotic agent is mandatory. Studies are needed to determine the role of second-line oral analgesics in terms of their overall toxicity and efficacy. In the meantime it is proposed that oral metamizole should be used only when other analgesics (e.g. paracetamol) have failed.