An unusual complication of cocaine toxicity.

A 25-year man presented to the Accident and Emergency Department complaining of dizziness and shortness of breath after taking 70 grams of cocaine over 10 hours. He said a friend had noticed that his skin had turned dark blue. On examination the patient was severely centrally and peripherally cyanosed. His pulse oximeter oxygen saturations were 88% on air. An arterial blood gas showed a methaemoglobin level of 45.6%. The patient was diagnosed with cocaine-induced methaemoglobinaemia and given methyl thioninium chloride (methylene blue). He made an uneventful recovery.