Drug Interaction Report

Alfuzosin and Telithromycin: Interaction Details

A pharmacist-reviewed analysis of the Alfuzosin and Telithromycin 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

Telithromycin

No brand names on record
+

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 297 documented Alfuzosin interactions, 34 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 alfuzosin plasma concentrations and an increased risk of QT interval prolongation

Interaction Deep Dive

The metabolism of alfuzosin, a CYP3A4 substrate, may be inhibited by concomitant administration of telithromycin, a strong CYP3A4 inhibitor. Increased alfuzosin plasma concentrations can lead to QT interval prolongation and torsade de pointes1. Prolongation of the QT interval has also been reported in patients receiving telithromycin 2. The concomitant use of alfuzosin and potent CYP3A4 inhibitors is contraindicated 1.

Why it happens (mechanism)

Inhibition of CYP3A4-mediated alfuzosin metabolism by telithromycin; additive effects on QT interval prolongation

Literature reports

1 report — tap to read

a) In a postmarketing study that evaluated the effect of concomitant administration of alfuzosin with another QT interval-prolonging drug of similar effect size, the observed QT interval prolongation was greater than that seen with either drug alone, but was not more than additive. The corrected (Fridericia) QT interval (QTcF) increased by 5.9 milliseconds (upper bound of 95% confidence interval (CI), 9.4 milliseconds). The QTcF increase observed with moxifloxacin 400 mg (positive control) was 10.2 milliseconds (upper bound 95% CI, 13.8 milliseconds). The mean placebo-subtracted QTcF increase following administration of alfuzosin 10 mg alone was 1.9 milliseconds (upper bound 95% CI, 5.5 milliseconds) 1.

Common questions

Can I take Alfuzosin and Telithromycin together?

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

How serious is the Alfuzosin and Telithromycin 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.

Questions for your pharmacist

  • Does my dose of Alfuzosin or Telithromycin 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, 2010. DailyMed
  2. Product Information: KETEK(R) oral tablets, telithromycin oral tablets. Sanofi-Aventis, US, LLC, Bridgewater, NJ, 2010. DailyMed
Was this write-up helpful?
Telithromycin

Keep reading about Telithromycin

All Telithromycin interactions (146)
Also serious with: Lovastatin Simvastatin Dihydroergotamine Injection Finerenone
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:

Telithromycin + Activated Charcoal American Hellebore Arsenic Cesium Ephedra Grapefruit Sida Cordifolia St. John's Wort + 170 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.