Drug interactions
Cyclobenzaprine + Duloxetine
Severity: Major
Cyclobenzaprine and Duloxetine: 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
Duloxetine and cyclobenzaprine both enhance serotonergic signaling, raising the risk of serotonin syndrome. Duloxetine also inhibits CYP2D6 and CYP1A2, which can modestly raise cyclobenzaprine exposure and its anticholinergic and sedative effects.
What this interaction means in plain words
Cyclobenzaprine and Duloxetine 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; Duloxetine belongs to Central Nervous System.
Why it happens
Additive serotonin reuptake inhibition plus possible CYP1A2 and CYP2D6 inhibition by duloxetine raising cyclobenzaprine levels.
What to do
Avoid if an alternative muscle relaxant is suitable. If used, monitor for serotonin toxicity and excess sedation or anticholinergic effects.
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 Cyclobenzaprine
- Cyclobenzaprine + Isocarboxazid Contraindicated
- Cyclobenzaprine + Linezolid Contraindicated
- Cyclobenzaprine + Phenelzine Contraindicated
- Cyclobenzaprine + Safinamide Contraindicated
- Cyclobenzaprine + Selegiline Contraindicated
- Cyclobenzaprine + Selegiline transdermal Contraindicated
Other interactions of Duloxetine
- Duloxetine + Isocarboxazid Contraindicated
- Duloxetine + Linezolid Contraindicated
- Duloxetine + Methylene blue Contraindicated
- Duloxetine + Phenelzine Contraindicated
- Duloxetine + Procarbazine Contraindicated
- Duloxetine + Rasagiline Contraindicated
Frequently asked questions
Can I take Cyclobenzaprine with Duloxetine?
MediHelp rates the interaction as major. Cyclobenzaprine and Duloxetine 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. Duloxetine and cyclobenzaprine both enhance serotonergic signaling, raising the risk of serotonin syndrome. Duloxetine also inhibits CYP2D6 and CYP1A2, which can modestly raise cyclobenzaprine exposure and its anticholinergic and sedative effects.
How serious is the interaction between Cyclobenzaprine and Duloxetine?
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 an alternative muscle relaxant is suitable. If used, monitor for serotonin toxicity and excess sedation or anticholinergic effects.
What other medicines interact with Cyclobenzaprine?
MediHelp also lists interactions of Cyclobenzaprine with, for example, Isocarboxazid, Linezolid, Phenelzine. The full list is on the Cyclobenzaprine page.
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