Methemoglobinemia secondary to over-the-counter Anbesol.
BACKGROUND
Methemoglobinemia is a potentially lethal condition which may result from exposure to benzocaine. It must be treated promptly, because it may cause a significant decrease in oxygen delivery to tissues and organs.


METHODS
A 39-year-old caucasian man presented to the emergency department (ED) with dental pain. After a review of systems and a dental exam, an oxygen saturation of 90% was noted. The patient reported no previous cardiac or pulmonary pathology, but did report using a large amount of over-the-counter Anbesol. A second oxygen saturation measurement had fallen to 87%. An arterial blood gas sample was taken, and the patient was found to have high levels of methemoglobin. He was transferred to the critical care ED and treated with 2 mg/kg intravenous methylene blue.


CONCLUSIONS
Dentists must be aware of the possible lethal effects of benzocaine toxicity, including methemoglobinemia. It is important to recognize the signs and symptoms and act in a judicious manner.
Stony Brook Medical Center, Stony Brook, New York, USA. orrdmd@gmail.com
Timothy M
TM
Orr
Daniel L
DL
Orr
D000287:Administration, Topical; D000328:Adult; D000779:Anesthetics, Local / Q000009:adverse effects*; D001566:Benzocaine / Q000009:adverse effects*; D004791:Enzyme Inhibitors / Q000627:therapeutic use; D006801:Humans; D008297:Male; D008708:Methemoglobinemia / Q000139:chemically induced* / Q000188:drug therapy; D008751:Methylene Blue / Q000627:therapeutic use; D004366:Nonprescription Drugs / Q000009:adverse effects*; D012651:Self Medication / Q000009:adverse effects*; D014098:Toothache / Q000188:drug therapy; D016896:Treatment Outcome
D000779:Anesthetics, Local; D004791:Enzyme Inhibitors; D004366:Nonprescription Drugs; D008751:Methylene Blue; D001566:Benzocaine