Methemoglobinemia from dapsone therapy for a suspected brown spider bite.

Recent reports have suggested the use of dapsone for brown spider bites. This drug, for many years restricted to use in cases of leprosy and rare dermatologic disorders, has significant side effects that must be recognized. A case of methemoglobinemia is reported in one such patient treated with dapsone. The difficulty of making the diagnosis of brown spider bite is discussed.