Drug Interaction Report

Avanafil and Terazosin: Interaction Details

A pharmacist-reviewed analysis of the Avanafil and Terazosin 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

Avanafil

Stendra Stendra®
+

Terazosin

Hytrin® Tezruly
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 113 documented Avanafil interactions, 60 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 of hypotension

Interaction Deep Dive

Concomitant use of avanafil (phosphodiesterase 5 inhibitor) and terazosin (alpha blocker) may increase the risk of symptomatic hypotension due to additive vasodilation. Although coadministration of avanafil and terazosin has not been studied, standing and supine blood pressures were decreased when avanafil was coadministered with the alpha blockers doxazosin and tamsulosin in studies of healthy subjects. When concomitant use is necessary, initiate avanafil at a dose of 50 mg, and initiate it only in patients stable on terazosin therapy1. When initiating terazosin in patients already receiving avanafil, begin terazosin at the lowest dose 21.

Why it happens (mechanism)

Additive vasodilation; additive hypotensive effects

Literature reports

2 reports — tap to read

a) Coadministration of avanafil with doxazosin was associated with a mean maximum decrease in supine and standing blood pressure of -6 mmHg (95% CI, -9.1 mmHg to -2.9 mmHg) and -2.5 mmHg (95% CI, -6.5 mmHg to 1.5 mmHg), respectively, compared with doxazosin plus placebo in a randomized, double-blind, crossover trial (n=24). Healthy subjects received doxazosin 1 mg for 1 day, 2 mg for 2 days, 4 mg for 4 days, and 8 mg for 11 days; avanafil 200 mg or placebo was administered on days 15 and 18, 1.3 hours after the doxazosin dose 1.

b) Coadministration of avanafil with tamsulosin was associated with a mean maximum decrease in supine and standing blood pressure of -3.1 mmHg (95% CI, -6.4 mmHg to 0.1 mmHg) and -3.6 mmHg (95% CI, -8.1 mmHg to 0.9 mmHg), respectively, compared with tamsulosin plus placebo in a randomized, double-blind, crossover trial (n=24). Healthy subjects received tamsulosin 0.4 mg daily for 11 days; avanafil 200 mg or placebo was administered on days 8 and 11, 3.3 hours after the tamsulosin dose 1.

Common questions

Can I take Avanafil and Terazosin together?

Increased risk of hypotension Always confirm with your pharmacist or prescriber before making any change.

How serious is the Avanafil and Terazosin 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.

From our Q&A

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

Questions for your pharmacist

  • Does my dose of Avanafil or Terazosin 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: STENDRA(R) oral tablets, avanafil oral tablets. Metuchen Pharmaceuticals LLC (per FDA), Freehold, NJ, 2022. DailyMed
  2. Product Information: TEZRULY(TM) oral soultion, terazosin oral solution. ANI Pharmaceuticals, Inc (per FDA), Baudette, MN, 2024. DailyMed
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Avanafil

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Terazosin

Keep reading about Terazosin

All Terazosin interactions (16) Terazosin drug information
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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:

Avanafil + Activated Charcoal American Mistletoe Grapefruit Hawthorn St. John's Wort Acacia Rigidula Adrafinil African Wild Potato + 136 more
Terazosin + Activated Charcoal American Hellebore American Mistletoe Tyramine Adrafinil Agmatine Algal Oil Andrographis + 129 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.