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Abstract

Methylene blue is a broad and potent therapeutic substance that is effective in treating various medical conditions in the Intensive Care Unit (ICU). Methylene blue (MB) has a multitarget mode of action that involves inhibiting nitric oxide synthase and guanylate cyclase, as well as serving as a redox agent. This makes it beneficial in treating various disorders in the intensive care unit, including septic and vasoplegic shock, methemoglobinemia, and Ifosfamide-induced encephalopathy. This comprehensive narrative review provides current evidence regarding MB use in the ICU setting, constituents of the chemical, clinical applications, its efficacy, safety, dosing, guidelines, actual recommendations for its usage, and future research directions for use in ICU. MB has demonstrated enhanced results for people who are critically unwell. However, when using MB as a supplementary medication, it is important to carefully examine the dosage and treatment schedule in order to obtain the best possible clinical outcome. This includes closely monitoring and making necessary adjustments, especially for patients with conditions such as renal or hepatic impairment, as well as Glucose-6-Phosphate Dehydrogenase (G6PD) deficiency. Further research and clinical trials are essential for expanding the understanding and application of MB in critical care.
Abbreviations: CPB: cardiopulmonary bypass, G6PD: Glucose-6-Phosphate Dehydrogenase, ICU: Intensive Care Unit, iNOS: inducible nitric oxide synthase, MAOIs: monoamine oxidase inhibitors, MB: Methylene blue, NADH: nicotinamide adenine dinucleotide hydrogen, NO: Nitric oxide, SNRIs: serotonin and norepinephrine reuptake inhibitors, SSRIs: selective serotonin reuptake inhibitors, IV: intravenous, TCAs: tricyclic antidepressants 
Keywords: Intensive care unit; Methylene blue; Review
Citation: Qutob RA. Methylene blue in the intensive care unit: A literature review. Anaesth. pain intensive care 2025;29(3):407-417. DOI: 10.35975/apic.v29i3.2829
Received: February 03, 2025; Revised: February 28, 2025; Accepted: March 05, 2025