Drug interactions
Erythromycin + Fentanyl
Severity: Major
Erythromycin and Fentanyl: 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
Erythromycin can substantially raise fentanyl concentrations, leading to prolonged sedation and potentially fatal respiratory depression. The risk is greatest after starting the inhibitor or stopping it later when fentanyl dosing is stable.
What this interaction means in plain words
Erythromycin and Fentanyl 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.
Erythromycin belongs to Anti Bacterial; Fentanyl belongs to Musculoskeletal.
Why it happens
Inhibition of CYP3A4 reduces fentanyl clearance.
What to do
Avoid if possible, or monitor closely for sedation and respiratory depression and reduce the fentanyl dose as needed. Re-evaluate the dose if erythromycin is withdrawn.
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 Fentanyl
- Alvimopan + Fentanyl Contraindicated
- Fentanyl + Isocarboxazid Contraindicated
- Fentanyl + Olanzapine / samidorphan Contraindicated
- Fentanyl + Phenelzine Contraindicated
- Fentanyl + Tranylcypromine Contraindicated
- Alfentanil + Fentanyl Major
Frequently asked questions
Can I take Erythromycin with Fentanyl?
MediHelp rates the interaction as major. Erythromycin and Fentanyl 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. Erythromycin can substantially raise fentanyl concentrations, leading to prolonged sedation and potentially fatal respiratory depression. The risk is greatest after starting the inhibitor or stopping it later when fentanyl dosing is stable.
How serious is the interaction between Erythromycin and Fentanyl?
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 if possible, or monitor closely for sedation and respiratory depression and reduce the fentanyl dose as needed. Re-evaluate the dose if erythromycin is withdrawn.
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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