Drug interactions
Thioridazine + Trifluoperazine
Severity: Major
Thioridazine and Trifluoperazine: major 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
Both phenothiazines prolong the QTc interval, so combining them increases the risk of torsades de pointes. Sedation, anticholinergic effects and extrapyramidal effects are also additive.
What this interaction means in plain words
Thioridazine and Trifluoperazine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Why it happens
Additive QT prolongation through hERG channel blockade.
What to do
Avoid concurrent use of two antipsychotics with QT effects; consolidate to a single agent. Monitor ECG and electrolytes if overlap is unavoidable.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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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 Trifluoperazine?
MediHelp rates the interaction as major. Thioridazine and Trifluoperazine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Both phenothiazines prolong the QTc interval, so combining them increases the risk of torsades de pointes. Sedation, anticholinergic effects and extrapyramidal effects are also additive.
How serious is the interaction between Thioridazine and Trifluoperazine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid concurrent use of two antipsychotics with QT effects; consolidate to a single agent. Monitor ECG and electrolytes if overlap is unavoidable.
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.
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