Acute toxic methemoglobinemia following dental analgesia.

This communication reports a case of acute toxic methemoglobinemia associated with hypoxia and general motor seizures following dental anesthesia using nitrous oxide and prilocaine hydrochloride. The dosage of prilocaine hydrochloride used was 5.6% of the recognized toxic dosage associated with clinical methemoglobinemia. The patient had no demonstrable congenital tendency toward methemoglobinemia, suggesting this case may represent a previously unreported and potentially fatal reaction to prilocaine hydrochloride. The etiology of the methemoglobin production, the diagnosis of the syndrome, and the emergency treatment are discussed.