Drug interactions
Quinine + Thioridazine
Severity: Contraindicated
Quinine 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
Thioridazine causes dose-related QT prolongation and quinine adds to this effect. The combination markedly increases the risk of torsades de pointes and sudden death.
What this interaction means in plain words
Quinine 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.
Quinine belongs to Anti Parasitic; Thioridazine belongs to Central Nervous System.
Why it happens
Additive prolongation of cardiac repolarization; quinine may also inhibit CYP2D6, raising thioridazine levels.
What to do
Avoid the combination and use a non-QT-prolonging antimalarial or antipsychotic. If quinine is unavoidable, withhold thioridazine and monitor ECG and electrolytes.
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 Quinine
- Arsenic trioxide + Quinine Contraindicated
- Dofetilide + Quinine Contraindicated
- Dronedarone + Quinine Contraindicated
- Ibutilide + Quinine Contraindicated
- Mefloquine + Quinine Contraindicated
- Nilotinib + Quinine 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 Quinine with Thioridazine?
MediHelp rates the interaction as contraindicated. Quinine 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. Thioridazine causes dose-related QT prolongation and quinine adds to this effect. The combination markedly increases the risk of torsades de pointes and sudden death.
How serious is the interaction between Quinine 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: Avoid the combination and use a non-QT-prolonging antimalarial or antipsychotic. If quinine is unavoidable, withhold thioridazine and monitor ECG and electrolytes.
What other medicines interact with Quinine?
MediHelp also lists interactions of Quinine with, for example, Arsenic trioxide, Dofetilide, Dronedarone. The full list is on the Quinine page.
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