Linezolid and methylene blue cause problems with psychiatric medications

Linezolid and methylene blue can cause serious reactions in patients who are taking serotonergic psychiatric medications, the FDA warned last week.

The agency has received reports of serious central nervous system reactions in patients who were taking a serotonergic psychiatric medication when they received either linezolid or methylene blue. Although the exact mechanism of this drug interaction is unknown, linezolid and methylene blue inhibit the action of monoamine oxidase, so it is believed that the combination of drugs causes high levels of serotonin to build up in the brain, known as serotonin syndrome. Signs and symptoms of serotonin syndrome include mental changes (confusion, hyperactivity, memory problems); muscle twitching; excessive sweating, shivering or shaking; diarrhea; trouble with coordination; and fever.

The FDA recommends that methylene blue or linezolid generally not be given to patients taking serotonergic drugs. However, there are some conditions that may be life-threatening or require urgent treatment with the drugs. For methylene blue, those exceptions may include when it is used in the emergency treatment of methemoglobinemia, ifosfamide-induced encephalopathy, or cyanide poisoning. For linezolid, exceptions may include treatment of vancomycin-resistant Enterococcus faecium infections or nosocomial pneumonia and complicated skin and skin structure infections, including cases caused by methicillin-resistant Staphylococcus aureus.