Drug interactions
Chloroquine + Cimetidine
Severity: Moderate
Chloroquine and Cimetidine: 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
Cimetidine reduces chloroquine clearance and has been reported to increase chloroquine levels. Higher exposure could raise the risk of toxicity including QT prolongation.
What this interaction means in plain words
Chloroquine and Cimetidine 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; Cimetidine belongs to Gastrointestinal Tract.
Why it happens
Cimetidine inhibits hepatic metabolism of chloroquine, and may reduce its renal clearance.
What to do
Avoid the combination if possible by using famotidine or a PPI; if used together, monitor for chloroquine toxicity and consider an ECG.
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 Cimetidine
- Cimetidine + Dofetilide Contraindicated
- Cimetidine + Fezolinetant Contraindicated
- Alfentanil + Cimetidine Major
- Atazanavir + Cimetidine Major
- Carmustine + Cimetidine Major
- Cimetidine + Citalopram 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 Cimetidine?
MediHelp rates the interaction as moderate. Chloroquine and Cimetidine 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. Cimetidine reduces chloroquine clearance and has been reported to increase chloroquine levels. Higher exposure could raise the risk of toxicity including QT prolongation.
How serious is the interaction between Chloroquine and Cimetidine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination if possible by using famotidine or a PPI; if used together, monitor for chloroquine toxicity and consider an ECG.
What other medicines interact with Cimetidine?
MediHelp also lists interactions of Cimetidine with, for example, Dofetilide, Fezolinetant, Alfentanil. The full list is on the Cimetidine page.
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