Drug interactions
Fentanyl + Nirmatrelvir
Severity: Major
Fentanyl and Nirmatrelvir: major interaction.
Last updated
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
Nirmatrelvir inhibits CYP3A4 and may raise fentanyl concentrations, increasing the risk of sedation and respiratory depression.
What this interaction means in plain words
Fentanyl and Nirmatrelvir 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.
Fentanyl belongs to Musculoskeletal; Nirmatrelvir belongs to Anti Virals.
Why it happens
Inhibition of CYP3A4-mediated fentanyl metabolism.
What to do
Monitor closely for respiratory depression and sedation and reduce the fentanyl dose if necessary. Continue monitoring for several days after the antiviral course ends.
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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Other interactions of Fentanyl
- Alvimopan + Fentanyl Contraindicated
- Fentanyl + Isocarboxazid Contraindicated
- Fentanyl + Olanzapine / samidorphan Contraindicated
- Fentanyl + Phenelzine Contraindicated
- Fentanyl + Tranylcypromine Contraindicated
- Alfentanil + Fentanyl Major
Other interactions of Nirmatrelvir
- Alfuzosin + Nirmatrelvir Contraindicated
- Amiodarone + Nirmatrelvir Contraindicated
- Apalutamide + Nirmatrelvir Contraindicated
- Carbamazepine + Nirmatrelvir Contraindicated
- Colchicine + Nirmatrelvir Contraindicated
- Dronedarone + Nirmatrelvir Contraindicated
Frequently asked questions
Can I take Fentanyl with Nirmatrelvir?
MediHelp rates the interaction as major. Fentanyl and Nirmatrelvir 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. Nirmatrelvir inhibits CYP3A4 and may raise fentanyl concentrations, increasing the risk of sedation and respiratory depression.
How serious is the interaction between Fentanyl and Nirmatrelvir?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor closely for respiratory depression and sedation and reduce the fentanyl dose if necessary. Continue monitoring for several days after the antiviral course ends.
What other medicines interact with Fentanyl?
MediHelp also lists interactions of Fentanyl with, for example, Alvimopan, Isocarboxazid, Olanzapine / samidorphan. The full list is on the Fentanyl page.
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