Drug interactions
Chloroquine + Thioridazine
Severity: Contraindicated
Chloroquine and Thioridazine: contraindicated interaction.
Last updated Sources: US FDA label
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 strongly prolongs the QT interval and chloroquine adds further prolongation. Chloroquine inhibits CYP2D6, which can raise thioridazine concentrations and magnify the risk of torsades de pointes.
What this interaction means in plain words
Chloroquine 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.
Chloroquine belongs to Anti Parasitic; Thioridazine belongs to Central Nervous System.
Why it happens
Additive QT prolongation plus chloroquine inhibition of CYP2D6-mediated thioridazine metabolism.
What to do
Do not combine; choose an alternative antimalarial or antipsychotic. Thioridazine labeling contraindicates use with QT-prolonging agents and CYP2D6 inhibitors.
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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References
Other interactions of Chloroquine
- Chloroquine + Cisapride Contraindicated
- Chloroquine + Dofetilide Contraindicated
- Chloroquine + Dronedarone Contraindicated
- Chloroquine + Droperidol Contraindicated
- Chloroquine + Panobinostat Contraindicated
- Chloroquine + Pimozide 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 Chloroquine with Thioridazine?
MediHelp rates the interaction as contraindicated. Chloroquine 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 strongly prolongs the QT interval and chloroquine adds further prolongation. Chloroquine inhibits CYP2D6, which can raise thioridazine concentrations and magnify the risk of torsades de pointes.
How serious is the interaction between Chloroquine 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; choose an alternative antimalarial or antipsychotic. Thioridazine labeling contraindicates use with QT-prolonging agents and CYP2D6 inhibitors.
What other medicines interact with Chloroquine?
MediHelp also lists interactions of Chloroquine with, for example, Cisapride, Dofetilide, Dronedarone. The full list is on the Chloroquine page.
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