CME Review ArticleMethylene Blue An Antidote for Methemoglobinemia and BeyondPushparajah Mak, Renita S. MD∗; Liebelt, Erica L. MD∗,†Author Information From the ∗Assistant Professor of Pediatrics (Pushparajah Mak) and Professor of Pediatrics (Liebelt), University of Arkansas for Medical Sciences †Medical and Research Director (Liebelt), Clinical Pharmacology and Toxicology, and Associate Medical Director (Liebelt), Arkansas Poison Drug and Information Center, University of Arkansas for Medical Sciences, Little Rock, AR. The authors, faculty, and staff in a position to control the content of this CME activity have disclosed that they have no financial relationships with, or financial interest in, any commercial organizations relevant to this educational activity. Reprints: Renita S. Pushparajah Mak, MD, University of Arkansas for Medical Sciences, Arkansas Children’s Hospital, 1 Children’s Way, Slot 512-19B, Little Rock, AR 72202 (e-mail: [email protected]). Pediatric Emergency Care: September 2021 - Volume 37 - Issue 9 - p 474-477 doi: 10.1097/PEC.0000000000002526 Buy CME Test Metrics Abstract Methylene blue has been in medicinal use for centuries and is best known as an antidotal treatment for acquired methemoglobinemia (MetHB). More recently, methylene blue has gained recognition for its efficacious use in the treatment of ifosfamide neurotoxicity and refractory vasoplegic shock in both the pediatric and adult critical care literature, extending its use beyond MetHB. Methylene blue’s mechanism of action is somewhat complex and based partly on its oxidizing capabilities, ironically the same mechanism that causes MetHB. This review will examine methylene blue’s use in the treatment of acquired MetHB and ifosfamide neurotoxicity and review the current literature regarding its role in critically ill pediatric and adult patients with refractory vasoplegic shock. Methylene blue’s pharmacologic actions, dosing, and adverse effects will also be discussed. Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.