Drug interactions
Quinidine + Verapamil
Severity: Major
Quinidine and Verapamil: major 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
Verapamil can raise quinidine concentrations, and quinidine can in turn raise verapamil exposure. Both drugs affect cardiac conduction and vascular tone, so the combination can cause hypotension, bradycardia, AV block and QT-related arrhythmia.
What this interaction means in plain words
Quinidine and Verapamil 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 belongs to Anti Parasitic; Verapamil belongs to Cardiovascular.
Why it happens
Verapamil inhibits CYP3A4 metabolism of quinidine, quinidine may reduce verapamil clearance, and both have additive negative effects on hemodynamics and conduction.
What to do
Monitor blood pressure, heart rate and ECG (PR and QTc intervals) when starting or stopping either drug. Consider lowering the quinidine dose and checking quinidine levels where available.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Quinidine and Verapamil, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 14 days on the web. No card needed.
Other interactions of Quinidine
- Adagrasib + Quinidine Contraindicated
- Arsenic trioxide + Quinidine Contraindicated
- Artemether / lumefantrine + Quinidine Contraindicated
- Chloroquine + Quinidine Contraindicated
- Dofetilide + Quinidine Contraindicated
- Dronedarone + Quinidine Contraindicated
Other interactions of Verapamil
- Dofetilide + Verapamil Contraindicated
- Flibanserin + Verapamil Contraindicated
- Lomitapide + Verapamil Contraindicated
- Lonafarnib + Verapamil Contraindicated
- Pimozide + Verapamil Contraindicated
- Acebutolol + Verapamil Major
Frequently asked questions
Can I take Quinidine with Verapamil?
MediHelp rates the interaction as major. Quinidine and Verapamil 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. Verapamil can raise quinidine concentrations, and quinidine can in turn raise verapamil exposure. Both drugs affect cardiac conduction and vascular tone, so the combination can cause hypotension, bradycardia, AV block and QT-related arrhythmia.
How serious is the interaction between Quinidine and Verapamil?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor blood pressure, heart rate and ECG (PR and QTc intervals) when starting or stopping either drug. Consider lowering the quinidine dose and checking quinidine levels where available.
What other medicines interact with Quinidine?
MediHelp also lists interactions of Quinidine with, for example, Adagrasib, Arsenic trioxide, Artemether / lumefantrine. The full list is on the Quinidine page.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
