Abstract

Methylene blue is a basic thiazine dye frequently used for histologic staining. In clinical toxicology settings, it is also used to treat clinically significant methemoglobinemia. It has dose-dependent oxidation or reduction properties, acting as a reducing agent at lower doses and as an oxidizing agent at higher doses. Hemolytic anemia and hyperbilirubinemia are known toxic effects of methylene blue treatment that have been reported clinically. A 42-year-old woman developed significant methemoglobinemia after acute dapsone overdose; she was treated appropriately with intravenous methylene blue in the therapeutic range. The patient's methemoglobin levels returned to normal. However, 2-4 days later she was noted to have rebound methemoglobinemia, hemolytic anemia, and hyperbilirubinemia. A repeat of Coomb's test and other anemia workups were negative. For management of methylene blue-induced hemolytic anemia, she was administered steroid therapy, N-acetylcysteine, and a blood transfusion. She ultimately recovered, and there were no long-term sequelae from the methylene blue poisoning.

• Keywords: Methylene blue;Hemolytic anemia;Dapsone;Poisoning;;