We report the case of a 27-year-old male patient who presented with refractory hypoxemia following the alleged inhalation of an unknown substance. The patient appeared to show worsening cyanosis despite increment of supplemental oxygenation. A drawn sample of the patient’s blood appeared chocolate brown in color, and disparity was noted between the patient’s oxygen saturation (SaO2) in his blood against the pulse oximetry (SpO2) reading. A diagnosis of toxic methemoglobinemia was established following elevated levels of methemoglobin discovered in his blood. The patient was started on methylene blue and instantaneously recovered without any complications. Methemoglobinemia should be suspected in any patient with refractory cyanosis, and early recognition of this condition could be potentially lifesaving.