Drug interactions
Thioridazine + Venlafaxine
Severity: Contraindicated
Thioridazine and Venlafaxine: contraindicated interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Thioridazine causes dose-related QT prolongation and torsades de pointes, and its metabolism depends on CYP2D6, which venlafaxine weakly inhibits. Venlafaxine may therefore both add to QT effects and raise thioridazine levels.
What this interaction means in plain words
Thioridazine and Venlafaxine are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two.
Thioridazine belongs to Central Nervous System; Venlafaxine belongs to Central Nervous System.
Why it happens
Additive QT prolongation, with CYP2D6 inhibition by venlafaxine increasing thioridazine exposure.
What to do
Avoid the combination and choose an alternative antipsychotic or antidepressant. Thioridazine labeling warns against drugs that inhibit its metabolism or prolong the QT interval.
What to ask your pharmacist
- Is there an alternative to one of these two medicines for me?
- If both are essential, who is monitoring me and how often?
- Which symptoms mean I should stop and seek help straight away?
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Other interactions of Venlafaxine
- Isocarboxazid + Venlafaxine Contraindicated
- Methylene blue + Venlafaxine Contraindicated
- Phenelzine + Venlafaxine Contraindicated
- Procarbazine + Venlafaxine Contraindicated
- Rasagiline + Venlafaxine Contraindicated
- Safinamide + Venlafaxine Contraindicated
Other interactions of Thioridazine
- Abiraterone + Thioridazine Contraindicated
- Adagrasib + Thioridazine Contraindicated
- Amiodarone + Thioridazine Contraindicated
- Amisulpride + Thioridazine Contraindicated
- Amitriptyline + Thioridazine Contraindicated
- Amoxapine + Thioridazine Contraindicated
Frequently asked questions
Can I take Thioridazine with Venlafaxine?
MediHelp rates the interaction as contraindicated. Thioridazine and Venlafaxine are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two. Thioridazine causes dose-related QT prolongation and torsades de pointes, and its metabolism depends on CYP2D6, which venlafaxine weakly inhibits. Venlafaxine may therefore both add to QT effects and raise thioridazine levels.
How serious is the interaction between Thioridazine and Venlafaxine?
MediHelp rates it contraindicated, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination and choose an alternative antipsychotic or antidepressant. Thioridazine labeling warns against drugs that inhibit its metabolism or prolong the QT interval.
What other medicines interact with Venlafaxine?
MediHelp also lists interactions of Venlafaxine with, for example, Isocarboxazid, Methylene blue, Phenelzine. The full list is on the Venlafaxine page.
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