Drug Interaction Report

Ketoconazole and Alfuzosin: Interaction Details

A pharmacist-reviewed analysis of the Ketoconazole and Alfuzosin 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

Ketoconazole

Extina Ketodan Kuric Nizoral Recorlev T8 Keto Flush Xolegel
+

Alfuzosin

UroXatral Uroxatral®
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 186 documented Ketoconazole interactions, 29 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
rapid
Evidence
probable
Severity
Contraindicated

What happens

Increased alfuzosin exposure and an increased risk of QT interval prolongation

Interaction Deep Dive

The concomitant use of alfuzosin (CYP3A4 substrates that prolong QT) and ketoconazole is contraindicated1 as it may increase alfuzosin exposure and may also increase the risk of QT interval prolongation and sometimes resulting in life-threatening ventricular tachyarrhythmias including occurrences of torsades de pointes, a potentially fatal arrhythmia 2. Repeated oral administration of ketoconazole 400 mg increased alfuzosin AUC 3.2-fold and Cmax 2.3-fold following a single dose of alfuzosin 10 mg. Repeated oral administration of ketoconazole 200 mg per day increased alfuzosin AUC 2.5-fold and Cmax 2.1-fold following a single dose of alfuzosin 10 mg 1.

Why it happens (mechanism)

Inhibition of CYP3A4-mediated metabolism of alfuzosin; additive QT interval prolongation

Literature reports

1 report — tap to read

a) Repeated oral administration of ketoconazole 400 mg increased alfuzosin AUC 3.2-fold and Cmax 2.3-fold following a single dose of alfuzosin 10 mg. Repeated oral administration of ketoconazole 200 mg per day increased alfuzosin AUC 2.5-fold and Cmax 2.1-fold following a single dose of alfuzosin 10 mg 1.

Common questions

Can I take Ketoconazole and Alfuzosin together?

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

How serious is the Ketoconazole and Alfuzosin interaction?

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

How quickly could this interaction happen?

The documented onset is "rapid". Effects can appear quickly, often within about 24 hours of combining the drugs.

How strong is the evidence for this interaction?

The evidence is graded "probable". Good supporting evidence, though not definitively proven.

Questions for your pharmacist

  • Does my dose of Ketoconazole or Alfuzosin 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: UROXATRAL(R) oral extended-release tablets, alfuzosin HCl oral extended-release tablets. sanofi-aventis U.S. LLC, Bridgewater, NJ, 2009. DailyMed
  2. Product Information: Ketoconazole oral tablet, ketoconazole oral tablet. Taro Pharmaceuticals U.S.A. Inc. (per DailyMed), Hawthorne, NY, 2024. DailyMed
Was this write-up helpful?
Ketoconazole

Keep reading about Ketoconazole

All Ketoconazole interactions (186)
Also serious with: Dihydroergotamine Injection Finerenone Lefamulin Loperamide
Alfuzosin

Keep reading about Alfuzosin

All Alfuzosin interactions (297) Alfuzosin drug information
Also serious with: Ritonavir Saquinavir Sparfloxacin Posaconazole
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:

Ketoconazole + Activated Charcoal Beer Grapefruit Siberian Cocklebur St. John's Wort Wine Acacia Rigidula Adrafinil + 174 more
Alfuzosin + Activated Charcoal Grapefruit St. John's Wort Acacia Rigidula Adrafinil African Wild Potato American Elder Astaxanthin + 131 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.