Rebound methaemoglobinaemia secondary to intentional sodium nitrite ingestion.

We report a case of rebounding severe methaemoglobinaemia secondary to sodium nitrite ingestion, despite several administrations of methylene blue. The patient's clinical course was characterised by a series of alternating improvements and deteriorations and proved challenging for treating clinicians. On discussion with poisoning experts, it was hypothesised that a small amount of sodium nitrite remained in the gastrointestinal tract leading to prolonged absorption of the causative agent.