Benzocaine-induced methemoglobinemia.

Methemoglobinemia is an uncommon but important complication associated with the use of topical anesthetics. We describe four cases of methemoglobinemia induced by topical benzocaine use. We review pathophysiology, early diagnosis, and therapy for this reversible yet potentially fatal condition. Physicians who use procedures involving the application of topical anesthetics need to be aware of this side effect to prevent significant morbidity and mortality.