Metamizole, which has antipyretic and pain-relieving properties, is generally used to treat fever in children who do not respond to paracetamol treatment. The most remarkable side effect of metamizole is that it causes myelotoxicity independently of dose. In this study, we aimed to present the clinical features of paediatric patients who developed agranulocytosis after the use of metamizole and draw attention to this side effect.
The patients who were admitted to Eskişehir Osmangazi University Faculty of Medicine Hospital, Pediatric Infectious Diseases and Pediatric Hematology Service, between January 1, 2015, and December 31, 2018, with a diagnosis of secondary agranulocytosis to metamizole use were examined retrospectively.
In all, 12 patients were included in the study; oral metamizole was used in these patients for fever reduction. The mean absolute neutrophil count was 225/mm ± 226 (0-600/mm) at admission, and the neutrophil value of 11 patients was < 500/mm. The mean length of hospitalisation of the patients was 9.92 ± 8 (3-28) days. Eight patients received intravenous antibiotic therapy and four patients received at least one of the following treatments: intravenous immunoglobulin, granulocyte colony-stimulating factor and methylprednisolone. Bone marrow aspiration examination showed neutrophil/band maturation delaying in the myeloid series with normocellular bone marrow in three patients. Hypocellularity in the bone marrow and decrease in myeloid precursors were observed in three patients. There were no fatal cases.
The development of agranulocytosis after the use of metamizole causes long-term hospitalisation and may require the use of medications in treatment management. Considering the availability of alternative options to treat fever and pain, and given the side-effect profile of metamizole, it should not be the preferred, first-line antipyretic treatment in children.