Drug interactions
Erythromycin + Fentanyl transdermal
Severity: Major
Erythromycin and Fentanyl transdermal: 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 inhibits CYP3A4, the main pathway clearing fentanyl, and can raise fentanyl levels. With a transdermal patch, the depot effect means toxicity can be prolonged and may persist after the inhibitor is stopped.
What this interaction means in plain words
Erythromycin and Fentanyl transdermal 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.
Why it happens
CYP3A4 inhibition reduces fentanyl clearance and raises plasma concentrations.
What to do
Avoid if possible and choose a non-CYP3A4-inhibiting antibiotic. If combined, monitor for respiratory depression and sedation frequently and reduce the patch dose as needed.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Erythromycin and Fentanyl transdermal, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 7 days on the web. No card needed.
References
Other interactions of Erythromycin
- Conivaptan + Erythromycin Contraindicated
- Dihydroergotamine intranasal + Erythromycin Contraindicated
- Dihydroergotamine + Erythromycin Contraindicated
- Domperidone + Erythromycin Contraindicated
- Dronedarone + Erythromycin Contraindicated
- Droperidol + Erythromycin Contraindicated
Frequently asked questions
Can I take Erythromycin with Fentanyl transdermal?
MediHelp rates the interaction as major. Erythromycin and Fentanyl transdermal 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 inhibits CYP3A4, the main pathway clearing fentanyl, and can raise fentanyl levels. With a transdermal patch, the depot effect means toxicity can be prolonged and may persist after the inhibitor is stopped.
How serious is the interaction between Erythromycin and Fentanyl transdermal?
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 and choose a non-CYP3A4-inhibiting antibiotic. If combined, monitor for respiratory depression and sedation frequently and reduce the patch dose as needed.
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.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
