Doxazosin and Vardenafil: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Vardenafil
Doxazosin
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.
What happens
Potentiation of hypotensive effects
Interaction Deep Dive
Studies with vardenafil and alpha-blockers suggest concomitant administration of vardenafil and this drug may potentiate hypotensive effects. Patients should be on a stable dose regimen of this drug prior to beginning treatment with vardenafil. For patients who are on a stable regimen of this drug, start vardenafil therapy at the lowest recommended initial dose of 5 mg (2.5 mg when used concomitantly with certain CYP3A4 inhibitors). Stepwise increase in alpha-blocker dose may be associated with further lowering of blood pressure in patients taking a PDE-5 inhibitor including vardenafil. If concurrent therapy is deemed necessary, consider a time interval between the dosing of vardenafil and an alpha blocker1. In patients taking alpha-blockers, do not initiate vardenafil therapy with vardenafil orally disintegrating tablets. Lower doses of vardenafil film-coated tablets should be used as initial therapy in these patients. If needed, consider switching to vardenafil oral disintegrating tablets from vardenafil film-coated tablets in patients being treated with alpha-blockers 2.
Why it happens (mechanism)
Additive effects on blood pressure
Literature reports
3 reports — tap to read
a) Hypotension has been reported with 5 mg vardenafil when administered to benign prostatic hyperplasia patients on chronic alpha-blocker therapy in two separate randomized, double blind, crossover studies of tamsulosin 0.4 mg daily (n=21) and terazosin 5 or 10 mg daily (n=21). A decrease in standing systolic blood pressure of more than 30 mmHg was reported in 5 patients who received terazosin and in 2 patients who received tamsulosin, when vardenafil was administered simultaneously. Hypotension was not observed in any patients when vardenafil and terazosin were administered 6 hours apart, but was reported in 1 patient when tamsulosin and vardenafil were separated by 6 hours 1.
b) One case of hypotension (defined as a decrease from baseline in standing systolic blood pressure of more than 30 mmHg) and 3 cases of dizziness were reported with simultaneous administration of vardenafil 10 mg or 20 mg and tamsulosin 0.4 mg or 0.8 mg daily in a randomized, double blind, 2-period crossover study in patients with benign prostatic hyperplasia (n=23) on stable tamsulosin therapy for 4 weeks or longer 1.
c) One case of hypotension (defined as a decrease from baseline in standing systolic blood pressure of more than 30 mmHg) and 3 cases of dizziness were reported with single doses of vardenafil 5 mg or 10 mg administered 4 hours after alfuzosin 10 mg daily in a randomized, double-blind, 3-period crossover study in patients with benign prostatic hyperplasia (n=24) treated with a stable dose of alfuzosin for 4 weeks or longer 1.
Common questions
Can I take Doxazosin and Vardenafil together?
Potentiation of hypotensive effects Always confirm with your pharmacist or prescriber before making any change.
How serious is the Doxazosin and Vardenafil interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
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.
From our Q&A
Real reader questions about these medications, each personally answered by our pharmacist:
Questions for your pharmacist
- Does my dose of Doxazosin or Vardenafil 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)
- Product Information: LEVITRA(R) oral tablets, vardenafil HCl oral tablets. Bayer Health Care Pharmaceuticals Inc (per FDA), Whippany, NJ, 2023. DailyMed
- Product Information: STAXYN(R) oral disintegrating tablets, vardenafil HCl oral disintegrating tablets. GlaxoSmithKline (per FDA), Research Triangle Park, NC, 2023. DailyMed
Keep reading about Vardenafil
Keep reading about Doxazosin
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