A case report of topical local anaesthetic cream inducing methaemoglobinaemia with an over-the-counter medication

What is known and objective: Methaemoglobinaemia is an altered state of haemoglobin caused by a variety of therapeutics which impairs tissue oxygenation. There are numerous cases in the literature of methaemoglobinaemia induced iatrogenically in a hospital environment. This is a case of methaemoglobinaemia induced by an over-the-counter topical local anaesthetic in a patient with widespread skin lesions. Case summary: A 55 year old woman presented with a generalised blistering rash and features of impaired tissue perfusion. She was found to have a methaemoglobinaemia and oxidative haemolysis. It was subsequently determined she had applied an over-the-counter topical local anaesthetic ointment. What is new and conclusion: This case presented a diagnostic challenge along with a rare case of methaemoglobinaemia induced by an over-the-counter topical local anaesthetic.