CriticalAntidepressant, irreversible non-selective monoamine oxidase inhibitor (MAO-A and MAO-B)×Selective 5-HT1B/1D serotonin receptor agonist
Updated · Methodology
Mechanism
Sumatriptan is a 5-HT1B/1D agonist, partly metabolised by MAO-A. Phenelzine irreversibly inhibits MAO – sumatriptan accumulates and excess serotonin triggers fatal serotonin syndrome.
Symptoms
Agitation, tachycardia, hyperthermia, myoclonus, hyperreflexia within hours.
Management
Combination contraindicated. 14 days after MAOI withdrawal before starting triptan.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.
Summary of a multi-drug list →
Medicine list: everything you take in one place →
Sources
- FDA: Imitrex (sumatriptan) prescribing information, Section 4 (2013)
- AEMPS: Ficha técnica: Sumatriptán (nº registro 66453), sección 4.3 (2025)– AEMPS, CIMA, nº registro 66453, revisión 11/2025, sección 4.3