Drug interactions
Chloroquine + Promethazine
Severity: Moderate
Chloroquine and Promethazine: moderate 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
Chloroquine inhibits CYP2D6 to a modest degree and may increase promethazine levels. Both drugs can also affect cardiac repolarization, which adds theoretical concern for QT prolongation.
What this interaction means in plain words
Chloroquine and Promethazine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Chloroquine belongs to Anti Parasitic; Promethazine belongs to Respiratory.
Why it happens
Chloroquine inhibits CYP2D6 metabolism of promethazine and both may prolong the QT interval.
What to do
Monitor for sedation and consider an ECG in patients with QT risk factors. Reduce the promethazine dose if adverse effects appear.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Promethazine
- Cabergoline + Promethazine Contraindicated
- Dopamine + Promethazine Contraindicated
- Ibutilide + Promethazine Contraindicated
- Pimozide + Promethazine Contraindicated
- Promethazine + Thioridazine Contraindicated
- Alfentanil + Promethazine Major
Other interactions of Chloroquine
- Chloroquine + Cisapride Contraindicated
- Chloroquine + Dofetilide Contraindicated
- Chloroquine + Dronedarone Contraindicated
- Chloroquine + Droperidol Contraindicated
- Chloroquine + Panobinostat Contraindicated
- Chloroquine + Pimozide Contraindicated
Frequently asked questions
Can I take Chloroquine with Promethazine?
MediHelp rates the interaction as moderate. Chloroquine and Promethazine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Chloroquine inhibits CYP2D6 to a modest degree and may increase promethazine levels. Both drugs can also affect cardiac repolarization, which adds theoretical concern for QT prolongation.
How serious is the interaction between Chloroquine and Promethazine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for sedation and consider an ECG in patients with QT risk factors. Reduce the promethazine dose if adverse effects appear.
What other medicines interact with Promethazine?
MediHelp also lists interactions of Promethazine with, for example, Cabergoline, Dopamine, Ibutilide. The full list is on the Promethazine page.
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