Severe methemoglobinemia due to topical dapsone misuse in a teenage girl.

Dapsone gel is a topical treatment for facial acne in adolescents and adults, and while systemic dapsone therapy is known to be associated with methemoglobinemia, once-daily topical dapsone has been well tolerated with few side effects in large randomized controlled trials. We describe the first reported case of severe methemoglobinemia in a healthy adolescent using daily topical dapsone. Although the medication was prescribed for facial use only, the patient reported topical use over her back and chest as well. This case illustrates the potential for significant systemic dapsone absorption even with daily topical dosing and demonstrates the need for clear anticipatory guidance to prevent the potential morbidity and mortality associated with methemoglobinemia from improper topical dapsone use.