Drug interactions
Cyclobenzaprine + Fentanyl
Severity: Major
Cyclobenzaprine 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
Cyclobenzaprine is sedating and anticholinergic, and together with fentanyl it can increase drowsiness and respiratory depression. Its serotonergic activity also gives a small risk of serotonin syndrome.
What this interaction means in plain words
Cyclobenzaprine 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.
Cyclobenzaprine belongs to Musculoskeletal; Fentanyl belongs to Musculoskeletal.
Why it happens
Additive CNS depression, with additional serotonergic effects.
What to do
Use the lowest effective doses and monitor for sedation, respiratory depression and signs of serotonin toxicity.
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 Fentanyl
- Alvimopan + Fentanyl Contraindicated
- Fentanyl + Isocarboxazid Contraindicated
- Fentanyl + Olanzapine / samidorphan Contraindicated
- Fentanyl + Phenelzine Contraindicated
- Fentanyl + Tranylcypromine Contraindicated
- Alfentanil + Fentanyl Major
Other interactions of Cyclobenzaprine
- Cyclobenzaprine + Isocarboxazid Contraindicated
- Cyclobenzaprine + Linezolid Contraindicated
- Cyclobenzaprine + Phenelzine Contraindicated
- Cyclobenzaprine + Safinamide Contraindicated
- Cyclobenzaprine + Selegiline Contraindicated
- Cyclobenzaprine + Selegiline transdermal Contraindicated
Frequently asked questions
Can I take Cyclobenzaprine with Fentanyl?
MediHelp rates the interaction as major. Cyclobenzaprine 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. Cyclobenzaprine is sedating and anticholinergic, and together with fentanyl it can increase drowsiness and respiratory depression. Its serotonergic activity also gives a small risk of serotonin syndrome.
How serious is the interaction between Cyclobenzaprine 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: Use the lowest effective doses and monitor for sedation, respiratory depression and signs of serotonin toxicity.
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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