Drug interactions
Diltiazem + Verapamil
Severity: Major
Diltiazem and Verapamil: major interaction.
Last updated Sources: UK SmPC
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
Both are non-dihydropyridine calcium channel blockers and CYP3A4 substrates and inhibitors, so each can raise the other's levels. Combined use produces additive effects on AV nodal conduction, heart rate, contractility and blood pressure. This may result in marked bradycardia, AV block, heart failure or hypotension.
What this interaction means in plain words
Diltiazem 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.
Diltiazem belongs to Cardiovascular; Verapamil belongs to Cardiovascular.
Why it happens
Additive pharmacodynamic calcium channel blockade at the AV node and vasculature, plus mutual CYP3A4 inhibition.
What to do
Avoid combining the two; use one non-dihydropyridine agent, adding a dihydropyridine if more blood pressure control is needed. If co-use is unavoidable, monitor ECG, heart rate and blood pressure closely.
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 Verapamil
- Dofetilide + Verapamil Contraindicated
- Flibanserin + Verapamil Contraindicated
- Lomitapide + Verapamil Contraindicated
- Lonafarnib + Verapamil Contraindicated
- Pimozide + Verapamil Contraindicated
- Acebutolol + Verapamil Major
Other interactions of Diltiazem
- Diltiazem + Flibanserin Contraindicated
- Diltiazem + Ivabradine Contraindicated
- Diltiazem + Lomitapide Contraindicated
- Diltiazem + Lonafarnib Contraindicated
- Acebutolol + Diltiazem Major
- Alfentanil + Diltiazem Major
Frequently asked questions
Can I take Diltiazem with Verapamil?
MediHelp rates the interaction as major. Diltiazem 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. Both are non-dihydropyridine calcium channel blockers and CYP3A4 substrates and inhibitors, so each can raise the other's levels. Combined use produces additive effects on AV nodal conduction, heart rate, contractility and blood pressure. This may result in marked bradycardia, AV block, heart failure or hypotension.
How serious is the interaction between Diltiazem 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: Avoid combining the two; use one non-dihydropyridine agent, adding a dihydropyridine if more blood pressure control is needed. If co-use is unavoidable, monitor ECG, heart rate and blood pressure closely.
What other medicines interact with Verapamil?
MediHelp also lists interactions of Verapamil with, for example, Dofetilide, Flibanserin, Lomitapide. The full list is on the Verapamil page.
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