Drug interactions
Fentanyl + Ritonavir
Severity: Major
Fentanyl and Ritonavir: 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
Ritonavir is a strong CYP3A4 inhibitor and markedly raises fentanyl exposure. This can cause serious or fatal respiratory depression, including delayed onset after the inhibitor is started.
What this interaction means in plain words
Fentanyl and Ritonavir 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; Ritonavir belongs to Anti Virals.
Why it happens
Potent inhibition of CYP3A4-mediated fentanyl metabolism by ritonavir.
What to do
Avoid if possible or use a substantially reduced fentanyl dose with frequent monitoring for respiratory depression and sedation. Consider a less CYP3A4-dependent opioid.
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 Ritonavir
- Alfuzosin + Ritonavir Contraindicated
- Amiodarone + Ritonavir Contraindicated
- Avanafil + Ritonavir Contraindicated
- Colchicine + Ritonavir Contraindicated
- Dronedarone + Ritonavir Contraindicated
- Eletriptan + Ritonavir Contraindicated
Frequently asked questions
Can I take Fentanyl with Ritonavir?
MediHelp rates the interaction as major. Fentanyl and Ritonavir 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. Ritonavir is a strong CYP3A4 inhibitor and markedly raises fentanyl exposure. This can cause serious or fatal respiratory depression, including delayed onset after the inhibitor is started.
How serious is the interaction between Fentanyl and Ritonavir?
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 use a substantially reduced fentanyl dose with frequent monitoring for respiratory depression and sedation. Consider a less CYP3A4-dependent opioid.
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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