Type 1 congenital methaemoglobinaemia is a rare cause of cyanosis which may manifest in affected individuals during concomitant illness. Treatment indications and aims differ from that of acquired methaemoglobinaemia. Type 1 methaemoglobinaemia is a distinct condition from the type 2 form which has a high mortality rate in infancy. A 25 year old male with known type 1 congential methaemoglobinaemia presented with cyanosis in the context of Influenza A with raised methaemoglobin levels on arterial blood gas analysis. The patient was assessed based on his level of ‘functional haemoglobin’ with no acute indication for IV methylene blue or ascorbic acid. Consideration could be given to prescription of these on a cosmetic basis for some patient populations.

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