Drug interactions
Diltiazem + Metoprolol
Severity: Major
Diltiazem and Metoprolol: 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
Diltiazem and metoprolol both depress sinus and AV nodal function and contractility, and diltiazem may modestly raise metoprolol exposure. The combination may cause severe bradycardia, AV block, hypotension or heart failure.
What this interaction means in plain words
Diltiazem and Metoprolol 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; Metoprolol belongs to Cardiovascular.
Why it happens
Additive negative chronotropic, dromotropic and inotropic effects, with possible reduced metoprolol clearance from diltiazem CYP inhibition.
What to do
Avoid in left ventricular dysfunction, bradycardia or conduction disease. If used, start low and monitor ECG, heart rate and blood pressure.
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 Metoprolol
- Metoprolol + Thioridazine Contraindicated
- Amifostine + Metoprolol Major
- Amiodarone + Metoprolol Major
- Atenolol-chlorthalidone + Metoprolol Major
- Atenolol + Metoprolol Major
- Betaxolol + Metoprolol 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 Metoprolol?
MediHelp rates the interaction as major. Diltiazem and Metoprolol 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 and metoprolol both depress sinus and AV nodal function and contractility, and diltiazem may modestly raise metoprolol exposure. The combination may cause severe bradycardia, AV block, hypotension or heart failure.
How serious is the interaction between Diltiazem and Metoprolol?
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 in left ventricular dysfunction, bradycardia or conduction disease. If used, start low and monitor ECG, heart rate and blood pressure.
What other medicines interact with Metoprolol?
MediHelp also lists interactions of Metoprolol with, for example, Thioridazine, Amifostine, Amiodarone. The full list is on the Metoprolol page.
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