Drug Interaction Report

Granisetron Transdermal Patch and Fluconazole: Interaction Details

A pharmacist-reviewed analysis of the Granisetron Transdermal Patch and Fluconazole 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

Fluconazole

Diflucan
+

Granisetron Transdermal Patch

Sancuso Sancuso®
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
Contraindicated
These should generally not be used together.
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 281 documented Granisetron Transdermal Patch interactions, 16 are rated contraindicated — 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
Contraindicated

What happens

Increased granisetron exposure and an increased risk of QT interval prolongation

Interaction Deep Dive

Concomitant use of fluconazole with other QT interval prolonging drugs which are metabolized via CYP3A, such as granisetron1, is contraindicated as it may increase granisetron exposure. Fluconazole-mediated CYP3A4 inhibition may continue for 4 to 5 days after discontinuation because of the long half-life 23.

Why it happens (mechanism)

Inhibition of CYP3A-mediated metabolism of granisetron; additive QT interval prolongation

Literature reports

1 report — tap to read

a) Case reports have described QT prolongation and torsades de pointes associated with fluconazole 45.

Common questions

Can I take Granisetron Transdermal Patch and Fluconazole together?

Increased granisetron exposure and an increased risk of QT interval prolongation Always confirm with your pharmacist or prescriber before making any change.

How serious is the Granisetron Transdermal Patch and Fluconazole interaction?

It is rated contraindicated. These should generally not be used together.

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.

From our Q&A

Real reader questions about these medications, each personally answered by our pharmacist:

Questions for your pharmacist

  • Does my dose of Granisetron Transdermal Patch or Fluconazole 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 (5)

  1. Product Information: KYTRIL(R) IV injection, granisetron HCl IV injection. Genentech USA, Inc, South San Francisco, CA, 2011.
  2. Product Information: DIFLUCAN(R) oral tablets, suspension, fluconazole oral tablets, suspension. Roerig (per FDA), New York, NY, 2024. DailyMed
  3. Product Information: DIFLUCAN(R) intravenous injection, fluconazole intravenous injection. Roerig (per FDA), New York, NY, 2024. DailyMed
  4. Khazan M & Mathis AS: Probable cause of torsades de pointes induced by fluconazole. Pharmacotherapy 2002; 22(12):1632-1637.
  5. Wassmann S, Nickenig G, & Bohm M: Long QT syndrome and torsade de pointes in a patient receiving fluconazole. Ann Intern Med 1999; 131:797. PubMed
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Fluconazole

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All Fluconazole interactions (166)
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Granisetron Transdermal Patch

Keep reading about Granisetron Transdermal Patch

All Granisetron Transdermal Patch interactions (281) Granisetron Transdermal Patch drug information
Also serious with: Phenelzine Pimozide Piperaquine Saquinavir
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:

Fluconazole + Activated Charcoal Beer Siberian Cocklebur Wine Adrafinil Ashwagandha Black Cohosh Boldo + 73 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.