Drug interactions
Perphenazine + Thioridazine
Severity: Contraindicated
Perphenazine and Thioridazine: 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
Perphenazine inhibits CYP2D6, increasing thioridazine exposure, and both drugs prolong the QT interval. This markedly raises the risk of torsades de pointes.
What this interaction means in plain words
Perphenazine and Thioridazine 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.
Perphenazine belongs to Central Nervous System; Thioridazine belongs to Central Nervous System.
Why it happens
CYP2D6 inhibition by perphenazine raises thioridazine levels, with additive hERG blockade.
What to do
Do not combine; thioridazine labeling contraindicates use with agents that inhibit its CYP2D6 metabolism and with other QT-prolonging drugs. Use a single antipsychotic with lower cardiac risk.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Perphenazine and Thioridazine, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 14 days on the web. No card needed.
Other interactions of Thioridazine
- Abiraterone + Thioridazine Contraindicated
- Adagrasib + Thioridazine Contraindicated
- Amiodarone + Thioridazine Contraindicated
- Amisulpride + Thioridazine Contraindicated
- Amitriptyline + Thioridazine Contraindicated
- Amoxapine + Thioridazine Contraindicated
Other interactions of Perphenazine
- Ibutilide + Perphenazine Contraindicated
- Perphenazine + Pimozide Contraindicated
- Adagrasib + Perphenazine Major
- Alfentanil + Perphenazine Major
- Amiodarone + Perphenazine Major
- Amisulpride + Perphenazine Major
Frequently asked questions
Can I take Perphenazine with Thioridazine?
MediHelp rates the interaction as contraindicated. Perphenazine and Thioridazine 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. Perphenazine inhibits CYP2D6, increasing thioridazine exposure, and both drugs prolong the QT interval. This markedly raises the risk of torsades de pointes.
How serious is the interaction between Perphenazine and Thioridazine?
MediHelp rates it contraindicated, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Do not combine; thioridazine labeling contraindicates use with agents that inhibit its CYP2D6 metabolism and with other QT-prolonging drugs. Use a single antipsychotic with lower cardiac risk.
What other medicines interact with Thioridazine?
MediHelp also lists interactions of Thioridazine with, for example, Abiraterone, Adagrasib, Amiodarone. The full list is on the Thioridazine page.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
