A probable case of metamizole-induced neutropaenia presenting 10 days after drug discontinuation

Metamizole (dipyrone) is a non-opioid analgesic and antipyretic agent belonging to the pyrazolone class. While it is widely used in many countries due to its favourable safety profile compared to non-steroidal anti-inflammatory drugs and opioids, its use has been associated with rare but potentially life-threatening haematologic adverse effects, including neutropaenia and agranulocytosis. These complications typically occur within 6-14 days of treatment initiation but may also arise earlier or significantly later, even after discontinuation of the drug. Given that late-onset neutropaenia after metamizole discontinuation may be underdiagnosed, we present the case of a 92-year-old woman who developed transient, likely drug-induced neutropaenia 10 days later, with spontaneous haematologic recovery. The patient remained asymptomatic, with no signs of infection or evidence of inflammatory or neoplastic systemic disease.