Drug interactions
Diltiazem + Erythromycin
Severity: Major
Diltiazem and Erythromycin: 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
Both are CYP3A4 substrates and inhibitors, so each can raise the other's concentrations. This can lead to hypotension, bradycardia, and increased erythromycin-associated QT risk.
What this interaction means in plain words
Diltiazem and Erythromycin 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; Erythromycin belongs to Anti Bacterial.
Why it happens
Mutual inhibition of CYP3A4 metabolism, with possible P-glycoprotein effects.
What to do
Prefer an alternative antibiotic such as azithromycin. If combined, monitor blood pressure, heart rate and ECG.
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 Erythromycin
- Conivaptan + Erythromycin Contraindicated
- Dihydroergotamine intranasal + Erythromycin Contraindicated
- Dihydroergotamine + Erythromycin Contraindicated
- Domperidone + Erythromycin Contraindicated
- Dronedarone + Erythromycin Contraindicated
- Droperidol + Erythromycin Contraindicated
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 Erythromycin?
MediHelp rates the interaction as major. Diltiazem and Erythromycin 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 CYP3A4 substrates and inhibitors, so each can raise the other's concentrations. This can lead to hypotension, bradycardia, and increased erythromycin-associated QT risk.
How serious is the interaction between Diltiazem and Erythromycin?
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 an alternative antibiotic such as azithromycin. If combined, monitor blood pressure, heart rate and ECG.
What other medicines interact with Erythromycin?
MediHelp also lists interactions of Erythromycin with, for example, Conivaptan, Dihydroergotamine intranasal, Dihydroergotamine. The full list is on the Erythromycin page.
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