The normal presentation of a patient with a drug induced methemoglobinemia is a low pulse oximetry (SpO₂) reading, usually in the mid 80% range, while having a very high PaO₂ on an arterial blood gas (ABG)1. We present a case where the initial ABG showed a very high PaO₂ and a metabolic alkalosis while the SpO₂ fluctuated (85%- 99%). Those findings combined with hemodynamic instability complicated the diagnosis and delayed optimal care.