Methemoglobinemia from topical benzocaine.

Acute cyanosis and methemoglobinemia developed following topical application and partial ingestion of benzocaine for esophagogastroduodenoscopy. A diagnosis of acute toxic methemoglobinemia should be considered when cyanosis, with or without neurologic symptoms, occurs following the use of local anesthetics in the absence of cardiopulmonary disease. Laboratory tests should include oxygen saturation and methemoglobin concentration. Management includes supplemental oxygen administration and intravenous methylene blue.