Nestosyl is usually used for dental pain in children. We report a methemoglobinemia after accidental ingestion of 10 ml in a 2 year-old girl. Cyanosis was cleared and O2 saturation and PaO2 were normalized 15 mn after methylene blue (1 mg/kg) administered intravenously. Nestosyl contains butoform, benzocaine, resorcine and 8-hydroxyquinoleine: the 3 latest can induce methemoglobinemia. The benefit of the drug is not demonstrated and this potentially severe side effect justifies its delivery only after medical prescription and information about its dangers.