MajorFirst-generation antipsychotics. Butyrophenone derivatives×SNRI (serotonin-norepinephrine reuptake inhibitor)
Updated · Methodology
Mechanism
Additive QT prolongation. Venlafaxine at high doses (above 150 mg/day) prolongs QT; haloperidol does so on its own (especially parenterally).
Symptoms
QT prolongation on ECG. Dizziness, syncope, palpitations. Severe cases: polymorphic ventricular tachycardia (torsades de pointes). Risk is higher with hypokalaemia and hypomagnesaemia.
Management
Avoid the combination with high venlafaxine doses and parenteral haloperidol. At low venlafaxine doses (75 mg) and oral haloperidol, the combination is acceptable with ECG monitoring at 2 weeks. Alternative antipsychotics with minimal QT effect: olanzapine or aripiprazole.
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.
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Sources
- FDA: Haloperidol tablet (Ajanta Pharma USA Inc.) – Prescribing Information (2008)– ; DailyMed setid 31e33656-2f53-49e6-9816-261ea2e6961a
- AEMPS: Ficha técnica: Venlafaxina (nº registro 67542), sección 4.5 (2024)– AEMPS, CIMA, nº registro 67542, revisión 03/2024, sección 4.5
- AEMPS: Ficha técnica: Haloperidol Esteve 2 mg/ml solución oral (nº registro 58355), secciones 4.4 y 4.5 (2020)– AEMPS, CIMA, nº registro 58355, revisión 07/2020, secciones 4.4 y 4.5