• Nam-Young Chung, Rajni Batra, Myrzia Itzkevitch, Donna Boruchov, and Mary Baldauf.
• Department of Pediatrics, Brookdale University Hospital Medical Center, Brooklyn, New York 11212, USA.
• J Emerg Med. 2010 Jun 1; 38 (5): 601-6.

BackgroundMethemoglobinemia is an uncommon cause of tissue hypoxia, but it can be life threatening if it is not identified and treated promptly.ObjectivesTo highlight the importance of understanding the potential risks of over-the-counter medications, especially in unsupervised use. Topical benzocaine must be used with caution, even in the healthy population.Case ReportWe report a case of methemoglobinemia secondary to topical benzocaine gel. A 6-year-old boy presented to our Pediatric Emergency Department with cyanosis, vomiting, and lethargy after using a gel-type, 7.5% benzocaine (Baby Orajel) for a toothache. Physical examination revealed dusky blue skin, tachycardia, tachypnea, and a normal neurologic examination. His percutaneous oxygen saturation remained 77-83% despite the administration of 100% oxygen. His arterial blood sample had a dark chocolate color appearance, and methemoglobinemia was suspected. His methemoglobin level was 69.9%, which is considered a lethal level. After a single dose of methylene blue (1 mg/kg/dose), cyanosis was reduced and oxygenation improved.ConclusionOver-the-counter topical benzocaine should be used with caution, and the presence of methemoglobinemia must be promptly identified and treated.Copyright 2010 Elsevier Inc. All rights reserved.

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