Drug Interaction Report

Butorphanol and Fentanyl Transdermal Patch: Interaction Details

A pharmacist-reviewed analysis of the Butorphanol and Fentanyl Transdermal Patch 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

Butorphanol

Butorphic Dolorex Solution Torbugesic Torphadine Vetorphic
+

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 35 documented Butorphanol interactions, 33 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

Reduced analgesic effect or precipitation of withdrawal symptoms, and an increased risk of serotonin syndrome

Interaction Deep Dive

Avoid concomitant use of fentaNYL with a mixed opioid agonist/antagonist or a partial agonist opioid analgesic as this may reduce the analgesic effect of fentaNYL and/or may precipitate withdrawal symptoms. Additionally, concomitant use may also increase the risk of serotonin syndrome. Serotonin syndrome symptoms may include mental status changes (eg, agitation, hallucinations, coma), autonomic instability (eg, tachycardia, labile blood pressure, hyperthermia), neuromuscular aberrations (eg, hyperreflexia, incoordination, rigidity), and/or gastrointestinal symptoms (eg, nausea, vomiting, diarrhea) and can be fatal. If concomitant use is warranted, carefully observe the patient, particularly during treatment initiation and dose adjustment. The onset of symptoms generally occurs within several hours to a few days of concomitant use but may occur later than that. Discontinue fentaNYL if serotonin syndrome is suspected4321.

Why it happens (mechanism)

Opioid receptor antagonism; additive serotonergic effects

Common questions

Can I take Butorphanol and Fentanyl Transdermal Patch together?

Reduced analgesic effect or precipitation of withdrawal symptoms, and an increased risk of serotonin syndrome Always confirm with your pharmacist or prescriber before making any change.

How serious is the Butorphanol and Fentanyl Transdermal Patch 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 Butorphanol or Fentanyl Transdermal Patch 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 (4)

  1. Product Information: DURAGESIC(R) transdermal system, fentanyl transdermal system. Janssen Pharmaceuticals Inc (per manufacturer), Titusville, NJ, 2018. DailyMed
  2. Product Information: ACTIQ(R) oral transmucosal lozenge, fentanyl citrate oral transmucosal lozenge. Teva Pharmaceuticals USA, Inc. (per FDA), Parsippany, NJ, 2023. DailyMed
  3. Product Information: Fentanyl citrate intravenous, intramuscular injection, fentanyl citrate intravenous, intramuscular injection. Hospira Inc (per FDA), Lake Forest, IL, 2023. DailyMed
  4. Product Information: FENTORA(R) buccal tablets, fentanyl citrate buccal tablets. Teva Pharmaceuticals USA Inc (per FDA), Parsippany, NJ, 2023.
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Butorphanol

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All Butorphanol interactions (35)
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Fentanyl Transdermal Patch

Keep reading about Fentanyl Transdermal Patch

All Fentanyl Transdermal Patch interactions (493) Fentanyl Transdermal Patch drug information
Also serious with: Ensitrelvir Samidorphan Safinamide Phenelzine
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:

Butorphanol + 1,4-butanediol Activated Charcoal Beer Gamma-hydroxybutyrate (ghb) Kava L-tryptophan Wine 5-htp + 92 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.