Drug interactions
Diltiazem + Timolol
Severity: Major
Diltiazem and Timolol: 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 slows sinus and AV node conduction and reduces contractility, and timolol adds to these effects. This can lead to severe bradycardia, AV block, hypotension, or heart failure decompensation.
What this interaction means in plain words
Diltiazem and Timolol 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; Timolol belongs to Cardiovascular.
Why it happens
Additive negative chronotropic, dromotropic, and inotropic effects; diltiazem may also reduce beta-blocker clearance.
What to do
Avoid in patients with conduction abnormalities or reduced ventricular function. If combined, use low doses 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 Timolol
- Acebutolol + Timolol Major
- Aldesleukin + Timolol Major
- Amifostine + Timolol Major
- Amiodarone + Timolol Major
- Arformoterol + Timolol Major
- Atenolol-chlorthalidone + Timolol 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 Timolol?
MediHelp rates the interaction as major. Diltiazem and Timolol 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 slows sinus and AV node conduction and reduces contractility, and timolol adds to these effects. This can lead to severe bradycardia, AV block, hypotension, or heart failure decompensation.
How serious is the interaction between Diltiazem and Timolol?
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 patients with conduction abnormalities or reduced ventricular function. If combined, use low doses and monitor ECG, heart rate, and blood pressure.
What other medicines interact with Timolol?
MediHelp also lists interactions of Timolol with, for example, Acebutolol, Aldesleukin, Amifostine. The full list is on the Timolol page.
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