Study summary · research use only
Methylene blue: a controversial diagnostic acid and medication?
Plain-language summary
Paraphrased from the published abstract below — not a verdict on whether anything works.
This narrative review of literature from MEDLINE, Web of Science, Scopus, and Cochrane examines potential risks of methylene blue (MB) administration in humans, a substance used diagnostically and in treatment of methemoglobinemia, vasoplegic syndrome, fosfamide-induced encephalopathy, cyanide intoxication, and detection of leaks or parathyroid corpuscle position during surgery. The authors state the basic toxicological characteristics of MB are unknown despite its long history of use, and describe reports of severe adverse effects that could outweigh benefits for a given indication. They report dose-dependent toxic effects including hemolysis, methemoglobinemia, nausea and vomiting, chest pain, dyspnoea, and hypertension, skin irritation and inflammatory response noted by some countries, and serotoninergic toxicity manifesting as neuromuscular hyperactivity. The review aims to summarize indications for MB and define its potential adverse effects.
Abstract
A narrative review of the literature was conducted to determine if the administration of methylene blue (MB) in humans has potential risks. Studies were identified from MEDLINE, Web of Science, Scopus, and Cochrane. MB is a diagnostic substance used during some diagnostic procedures and also a part of the treatment of several diseases including methemoglobinemia, vasoplegic syndrome, fosfamide-induced encephalopathy, and cyanide intoxication, and the detection of leaks or position of parathyroid corpuscles during surgery. Although the use of MB is historically justified, and it ought to be safe, because it originated as a diagnostic material, the basic toxicological characteristics of this substance are unknown. Despite reports of severe adverse effects of MB, which could significantly exceed any possible benefits evaluated for the given indication. Therefore, the clinical use of MB currently represents a controversial problem given the heterogeneity of available data and the lack of preclinical data. This is in conflict with standards of safe use of such substances in human medicinal practice. The toxic effects of the application of MB are dose-dependent and include serious symptoms such as hemolysis, methemoglobinemia, nausea and vomitus, chest pain, dyspnoea, and hypertension. Some countries regard MB as harmful because of the resulting skin irritation and triggering of an adverse inflammatory response. MB induced serotoninergic toxicity clinically manifests as neuromuscular hyperactivity. This review aims to summarize the current understanding concerning the indications for MB administration and define the potential adverse effects of MB.
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