Semaglutide-associated agranulocytosis requiring hospitalisation and granulocyte colony-stimulating factor: a case report.

Semaglutide, a glucagon-like peptide-1 receptor agonist (GLP-1RA), is widely used in obesity and type 2 diabetes. Although generally well tolerated, severe haematological adverse reactions remain poorly characterised. A 48-year-old woman treated with subcutaneous semaglutide for obesity developed febrile agranulocytosis with an absolute neutrophil count of 0.0×10⁹/L after several months of therapy. Baseline blood counts had been normal prior to treatment. Bone marrow aspirate and biopsy showed preserved cellularity with granulocytic maturation arrest at the promyelocyte/myelocyte stage. Semaglutide was discontinued and empiric broad-spectrum antibiotics together with a single dose of granulocyte colony-stimulating factor were administered, resulting in rapid and sustained haematological recovery. Alternative aetiologies were systematically investigated. Causality assessment using the Naranjo algorithm suggested a possible drug-related reaction (score 3). Although causality cannot be definitively established from a single case, the temporal relationship, objective haematological findings, positive dechallenge and systematic exclusion of alternative aetiologies support a possible drug-related association. This case highlights a rare but serious adverse drug reaction and underscores the importance of multidisciplinary causality assessment and pharmacovigilance.