Drug Interaction Report

Fentanyl Transdermal Patch and Vilazodone: Interaction Details

A pharmacist-reviewed analysis of the Fentanyl Transdermal Patch and Vilazodone interaction: the documented clinical effects, severity rating, onset, mechanism, and management considerations, with cited references throughout.

AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature

Vilazodone

Viibryd
+

Fentanyl Transdermal Patch

Duragesic®
Dr. Brian Staiger, PharmD, BCPS
Medically reviewed by
Dr. Brian Staiger, PharmD, BCPS
Updated Aug 8, 2026
Editorial policy · Data sources
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Interaction severity
Major
Potentially serious — often needs a change or close monitoring.
How we grade severity & evidence

Severity levels

  • Contraindicated: These should generally not be used together.
  • Major: Potentially serious — often needs a change or close monitoring.
  • Moderate: Can be significant — usually manageable with monitoring.
  • Minor: Usually limited clinical impact.

Evidence grades

  • Established: Well documented — supported by controlled studies or strong clinical data.
  • Probable: Good supporting evidence, though not definitively proven.
  • Suspected: Some evidence suggests this interaction, but it is not well established.
  • Possible: Limited or conflicting evidence; the interaction may occur.
  • Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.

Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.

Of 493 documented Fentanyl Transdermal Patch interactions, 469 are rated major — including this one.
Worried about symptoms right now? Contact your pharmacist or prescriber, or call Poison Control at 1-800-222-1222 (US). Call 911 for an emergency.
Onset
unspecified
Evidence
theoretical
Severity
Major

What happens

Increased risk for serotonin syndrome (hypertension, hyperthermia, myoclonus, mental status changes)

Interaction Deep Dive

Serotonin syndrome has been reported with vilazodone monotherapy and in combination with other serotonergic drugs; coadministration with another serotonergic drug may increase risk for serotonin syndrome1. Increased serotonin levels which may produce additive serotonergic effects can occur if serotonergic agents are taken concurrently. Symptoms of serotonin syndrome include neuromuscular abnormalities (including hyperreflexia, tremor, muscle rigidity, clonus, peripheral hypertonicity, and shivering), autonomic hyperactivity (including tachycardia, mydriasis, diaphoresis, the presence of bowel sounds, and diarrhea), and mental status changes (including agitation and delirium). Serotonin syndrome can be life-threatening 2. Therefore, exercise caution with concomitant use of vilazodone and this drug. Discontinue use of both vilazodone and the concomitant serotonergic agent immediately if symptoms of serotonin syndrome emerge and initiate supportive symptomatic treatment. If concomitant use of vilazodone with other serotonergic drugs is clinically warranted, inform patients of the increased risk for serotonin syndrome and monitor for symptoms 1.

Why it happens (mechanism)

Additive serotonergic effects

Common questions

Can I take Fentanyl Transdermal Patch and Vilazodone together?

Increased risk for serotonin syndrome (hypertension, hyperthermia, myoclonus, mental status changes) Always confirm with your pharmacist or prescriber before making any change.

How serious is the Fentanyl Transdermal Patch and Vilazodone interaction?

It is rated major. Potentially serious — often needs a change or close monitoring.

How quickly could this interaction happen?

The documented onset is "unspecified". The timing of this interaction is not well characterized.

How strong is the evidence for this interaction?

The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.

Questions for your pharmacist

  • Does my dose of Fentanyl Transdermal Patch or Vilazodone need adjusting while I take them together?
  • What symptoms should prompt me to call you or my prescriber right away?
  • Does the timing of my doses matter for this combination?
  • Is there a safer alternative to one of these medications for me?

References (2)

  1. Product Information: VIIBRYD(R) oral tablets, vilazodone HCl oral tablets. Allergan USA Inc (per FDA), Madison, NJ, 2023. DailyMed
  2. Boyer EW & Shannon M: The serotonin syndrome. N Eng J Med 2005; 352(11):1112-1120. PubMed
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Vilazodone

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Fentanyl Transdermal Patch

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Beyond drug–drug

These medications also interact with supplements

Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:

Vilazodone + Activated Charcoal Grapefruit Lithium St. John's Wort 1,3-dmaa 5-htp Acacia Rigidula Acetyl-l-carnitine + 168 more

major · moderate · minor — check everything you take with our drug–supplement interaction checker.

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This information is for education, not a substitute for professional medical advice. Do not start, stop, or change any medication without talking to your pharmacist or prescriber.