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Serotonin Syndrome after Cardiopulmonary Bypass: A Case Demonstrating the Interaction Between Methylene Blue and Selective Serotonin Reuptake Inhibitors

Hanna, Engy R. MD; Clark, Jeffrey A. MD

doi: 10.1213/XAA.0000000000000010
Case Reports: Case Report

Methylene blue, a drug used to treat vasoplegia and methemoglobinemia, also inhibits monoamine oxidase-A. When given in combination with serotonergic medications, methylene blue can lead to serotonin excess syndrome. Given the widespread use of serotonergic medication to treat depression, anesthesia providers should be aware of this potentially lethal interaction. Patients undergoing cardiopulmonary bypass for cardiac surgery are a specific population at risk for postbypass vasoplegic shock. The use of methylene blue to treat vasoplegia in this group of patients should be weighed in light of their current medications and potential drug interactions.

From the Department of Anesthesiology, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire.

Accepted for publication October 18, 2013.

Funding: No funding.

The authors declare no conflicts of interest.

Address correspondence to Engy R. Hanna, MD, Department of Anesthesiology, Dartmouth-Hitchcock Medical Center, One Medical Center Dr., Lebanon, NH 03756. Address e-mail to

© 2014 International Anesthesia Research Society