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.

CASE DESCRIPTION

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.

CLINICAL IMPLICATIONS

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.