Critical
Methylthioninium chloride (methylene blue) × Sertraline
Antidotes (V03AB17). The drug has one FDA-approved indication – methaemoglobinaemia. Biohacker use is off-label.×Selective serotonin reuptake inhibitors (SSRIs)
Mechanism
Methylene blue (methylthioninium chloride) given intravenously is a potent reversible MAO-A inhibitor. Sertraline (SSRI) raises synaptic serotonin. Co-administration sharply amplifies serotonergic transmission.
Symptoms
Serotonin syndrome: agitation, confusion, tremor, myoclonus, hyperreflexia, dilated pupils. Autonomic features: profuse sweating, tachycardia, hypertension, fever above 38.5 °C. Severe cases progress to seizures, rhabdomyolysis, disseminated intravascular coagulation, and death. First signs appear within hours of concurrent dosing.
Management
Avoid the combination. IV methylene blue is reserved for emergencies (methaemoglobinaemia, septic shock), and sertraline is stopped at least 5 days before any planned dose. For emergency use on an SSRI, monitor temperature, pulse, and muscle tone in ICU with cyproheptadine available.