Abstract Methemoglobinemia represents a rare blood disorder which occurs through the oxidation of hemoglobin (Hb) from its ferrous (Fe 2+ ) to ferric (Fe 3+ ) state, thus disabling its oxygen transport function. The condition leads to functional hypoxia which manifests as cyanosis that does not respond to oxygen therapy. The condition affects neonates most severely because their enzymatic systems are not fully developed and their fetal Hb has a tendency to become oxidized. We report a case of a 4-week-old male term infant who developed severe cyanosis after receiving excessive EMLA cream (lidocaine/prilocaine) for circumcision pain relief. The methemoglobin level reached 52% which established the diagnosis. The administration of methylene blue brought about a quick clinical recovery of the patient. The case demonstrates the difficulties in diagnosis and potential dangers of using topical anesthetics in newborns while showing why early detection and proper treatment and parental education remain crucial.