Safety of metamizole (dipyrone) for the treatment of mild to moderate pain-an overview of systematic reviews

Metamizole, as known as dipyrone or novaminsulfone is widely used, especially in Latin America, for its analgesic and antipyretic function. However, several countries have banned it due to the risk of agranulocytosis, skin necrosis, and other serious adverse effects. To assess the safety of metamizole compared to other commonly used non-opioid analgesics (paracetamol, ibuprofen, and acetylsalicylic acid). An overview of systematic reviews. The searches were performed in the PubMed, Cochrane Library, Embase, Scopus and LILACS databases. Systematic reviews of randomized and nonrandomized clinical trials with adult patients with mild to moderate pain that assessed the adverse effects of metamizole were included. A methodological quality assessment was performed through ROBIS. The protocol of this systematic review was submitted to the International Prospective Register of Systematic Reviews (Prospero, CRD42021295272). Of 387 identified studies, four were included, with a total of 20,643 participants, all submitted to a single dose by oral, intramuscular, or intravenous route. No study reported a serious adverse effect. However, 60 of 778 patients (7.7%) who used metamizole; 120/828 (14.5%) who used acetylsalicylic acid; 56/443 (12.6%) who used paracetamol; and 27/213 (12.7%) who used ibuprofen had mild adverse effects. A complementary statistical analysis showed that metamizole, at any dose, has a 38.8% lower chance of adverse effects compared to paracetamol and 46.8% compared to acetylsalicylic acid. The results shows that metamizole is a safe drug with evidence of a lower incidence of adverse effects compared to paracetamol and acetylsalicylic acid.