Evidence map›Paper›PMID 41458260›Full record

ArticleOxford medical case reports2025

Methylene blue-induced Hemolysis in a patient with lidocaine-induced Methemoglobinemia: a case report.

Murad Mehmood, Fatema Jaber A Almarri

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Article in Oxford medical case reports, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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1 · What the graph read from it

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4 · The record

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5 · Who and what money

Authors and funding

2 authors.

Murad MehmoodDepartment of Emergency Medicine, Hamad General Hospital, Al Rayyan Road, Hamad Medical City (Zone 37), Ad Dawhah (Doha Municipality), State of Qatar, P.O. Box 3050, Doha 16060, Qatar.ORCID https://orcid.org/0009-0003-5434-6656
Fatema Jaber A AlmarriDepartment of Emergency Medicine, Hamad General Hospital, Al Rayyan Road, Hamad Medical City (Zone 37), Ad Dawhah (Doha Municipality), State of Qatar, P.O. Box 3050, Doha 16060, Qatar.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

backgroundMethemoglobinemia is an uncommon but potentially life-threatening disorder where hemoglobin iron is oxidized to the ferric state, impairing oxygen transport. Topical anesthetics such as lidocaine can induce methemoglobinemia. Methylene blue (MB) is the first-line antidote, but high doses can oxidize hemoglobin and may precipitate hemolysis even in individuals with normal glucose-6-phosphate dehydrogenase (G6PD) activity. CASE PRESENTATION: A 31-year-old woman with recurrent genital herpes self-applied excessive 5% lidocaine cream (≈3 tubes/day) for two weeks. She presented with progressive fatigue, cyanosis and hypoxemia. Arterial blood gas showed methemoglobin 13.6%. She received intravenous MB at another hospital and subsequently developed severe anemia (hemoglobin 6.6 g/dL) with laboratory evidence of intravascular hemolysis. G6PD activity was normal. Supportive management included high-flow oxygen, oral ascorbic acid, intravenous antivirals and antibiotics, and transfusion of two units of packed red blood cells. Methemoglobin levels and hemoglobin gradually normalized, and she was discharged in stable condition.

conclusionThis case illustrates the paradoxical risk of MB-induced hemolysis in a G6PD-sufficient patient. Clinicians should consider alternative treatments such as ascorbic acid when managing methemoglobinemia and educate the public on safe use of topical anesthetics.

Indexed as

ascorbic acid/therapeutic useHemolysis/chemically inducedlidocaine/toxicityMethemoglobinemia/chemically inducedmethylene blue/adverse effects

Identifiers

PMID41458260
PMCPMC12741446

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