Drug interactions
Ciprofloxacin + Quinidine
Severity: Major
Ciprofloxacin and Quinidine: major 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
Quinidine markedly prolongs the QT interval and carries a well-known risk of torsades de pointes. Ciprofloxacin has a smaller QT effect but can add to this risk, particularly in patients with other predisposing factors.
What this interaction means in plain words
Ciprofloxacin and Quinidine 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.
Ciprofloxacin belongs to Anti Bacterial; Quinidine belongs to Anti Parasitic.
Why it happens
Additive inhibition of cardiac potassium channels, prolonging repolarization.
What to do
Prefer a non-QT-prolonging antibiotic when possible. If the combination is unavoidable, monitor ECG and keep potassium and magnesium within normal range.
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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References
Other interactions of Ciprofloxacin
- Agomelatine + Ciprofloxacin Contraindicated
- Ciprofloxacin + Fezolinetant Contraindicated
- Ciprofloxacin + Thioridazine Contraindicated
- Ciprofloxacin + Tizanidine Contraindicated
- Ciprofloxacin + Vandetanib Contraindicated
- Alosetron + Ciprofloxacin Major
Other interactions of Quinidine
- Adagrasib + Quinidine Contraindicated
- Arsenic trioxide + Quinidine Contraindicated
- Artemether / lumefantrine + Quinidine Contraindicated
- Chloroquine + Quinidine Contraindicated
- Dofetilide + Quinidine Contraindicated
- Dronedarone + Quinidine Contraindicated
Frequently asked questions
Can I take Ciprofloxacin with Quinidine?
MediHelp rates the interaction as major. Ciprofloxacin and Quinidine 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. Quinidine markedly prolongs the QT interval and carries a well-known risk of torsades de pointes. Ciprofloxacin has a smaller QT effect but can add to this risk, particularly in patients with other predisposing factors.
How serious is the interaction between Ciprofloxacin and Quinidine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Prefer a non-QT-prolonging antibiotic when possible. If the combination is unavoidable, monitor ECG and keep potassium and magnesium within normal range.
What other medicines interact with Ciprofloxacin?
MediHelp also lists interactions of Ciprofloxacin with, for example, Agomelatine, Fezolinetant, Thioridazine. The full list is on the Ciprofloxacin page.
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