Dapsone-induced methemoglobinemia: case of the blue lady.

Methemoglobinemia is a life-threatening condition that can be difficult to diagnose. While methemoglobinemia can be congenital and should be considered in cyanotic infants,1 it is more often an adverse medication effect, most commonly related to dapsone use.2 As up to 1 in 9 emergency department visits in Canada might be owing to adverse medication effects, physicians and other health care providers should routinely consider the relationship between medications and atypical clinical symptoms.3 We describe the diagnosis and management of a patient with acquired methemoglobinemia as a result of dapsone use.