MajorSSRI (selective serotonin reuptake inhibitor)×SNRI (serotonin-norepinephrine reuptake inhibitor)
Updated · Methodology
Mechanism
Venlafaxine blocks serotonin and noradrenaline reuptake, so the serotonergic effect stacks with an SSRI. Its SmPC bans only irreversible MAOIs, describing other serotonergic combinations as ones to be watched. QTc prolongation and torsade were recorded post-marketing, mostly in overdose.
Symptoms
Serotonin syndrome: agitation, confusion, tremor, myoclonus, hyperreflexia, sweating, diarrhoea, tachycardia, and in severe cases hyperthermia and rigidity. Symptoms usually appear within a day of adding the second drug or raising the dose. In patients with cardiac risk factors QTc is tracked separately.
Management
The pair usually appears while switching from one antidepressant to another, and the overlap is kept short. Agitation, tremor, sweating and hyperthermia in the first days after a dose change are the warning signs.
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: Effexor XR (venlafaxine) prescribing information (2017)– ; DailyMed setid c848a5d8-ba94-4c84-80e3-0bf35fb8e32e
- AEMPS: Ficha técnica de Seropram 30 mg (citalopram) (2024)– AEMPS CIMA, nregistro 63564, revisión 01/2024, secciones 4.2, 4.3 y 4.4
- AEMPS: Ficha técnica de Dobupal 50 mg (venlafaxina) (2024)– AEMPS CIMA, nregistro 60667, revisión 03/2024, secciones 4.4 y 4.5