Mesalazine-induced neutropenia: a rare idiosyncratic reaction

Mesalazine is a 5-aminosalicylate commonly used in the treatment of ulcerative colitis. It has been very rarely associated with neutropenia. We report a woman in her 30s who developed neutropenia 2 years after starting mesalazine. She had not been started on any other medications and extensive investigation for alternative causes of neutropenia were unremarkable. Mesalazine was discontinued and her neutrophil count normalised within 2 weeks.