Critical
Linezolid × Methylthioninium chloride (methylene blue)
Oxazolidinone antibiotic×Antidotes (V03AB17). The drug has one FDA-approved indication – methaemoglobinaemia. Biohacker use is off-label.
Mechanism
Linezolid is a reversible MAO inhibitor with antibacterial activity. IV methylene blue is a reversible MAO-A inhibitor. Two MAO inhibitors together raise the risk of hypertensive crisis and serotonin syndrome even without an SSRI on board.
Symptoms
Hypertensive crisis, tachycardia, severe headache, fever, agitation, confusion. With concomitant serotonergics (SSRI, SNRI, TCA, tramadol), full serotonin syndrome may develop with myoclonus, hyperreflexia, and rhabdomyolysis.
Management
Avoid the combination. For emergency methylene blue use in a patient on linezolid, give for life-threatening indications under ICU monitoring of blood pressure, pulse, and temperature. Pause linezolid if feasible; stop both at the first sign of hypertensive crisis.