Dapsone Induced Methemoglobinemia in a 16-Year-Old Female with Dermatitis Herpetiformis: A Case Report

Abstract

Background: Methemoglobinemia is a rare but potentially life-threatening disorder of oxygen carrying capacity, requiring prompt diagnosis. It could be congenital or acquired. This study presents a rare case of dapsone induced methemoglobinemia in a 16-year-old girl, managed with intravenous methylene blue. Case Presentation: A 16-year-old girl presented to the emergency department with a history of sudden loss of consciousness without seizure activity or trauma. The patient had a room air saturation of 76%. Despite high-flow oxygen therapy, oxygen saturation did not improve. Methemoglobinemia was suspected based on clinical signs. Methemoglobin levels came back >30%. Treatment was initiated with intravenous methylene blue at a dose of 1mg/kg. Over the course of next 5 days, intravenous methylene blue was repeated as required to a maximum dose of 7 mg/kg. The patient’s cyanosis resolved, oxygen saturation normalized to 96% on room air, and methemoglobin levels decreased to 17%. Conclusion: This case underscores the need for a high index of suspicion for methemoglobinemia in patients presenting with unexplained cyanosis and refractory hypoxia, especially in the context of known oxidizing agents like dapsone. Early diagnosis and intervention remain key to favorable outcomes.