Maoi Interactions

Monoamine oxidase inhibitors block MAO-A in the gut and liver, preventing the breakdown of dietary tyramine. Unmetabolized tyramine triggers a massive release of stored norepinephrine, producing a hypertensive crisis ('cheese reaction') with severe blood pressure spikes, stroke, or death.

St. John's Wort inhibits serotonin, dopamine, and norepinephrine reuptake and has weak MAOI activity in vitro. Combined with a prescription MAOI, monoamine clearance is blocked at multiple levels, producing serotonin syndrome and/or hypertensive crisis.

5-HTP is the direct precursor to serotonin and bypasses the rate-limiting step of serotonin synthesis. Combined with an MAOI, which blocks serotonin breakdown, intracellular and synaptic serotonin can rise to toxic levels, producing serotonin syndrome.