Dofetilide and Vardenafil: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Dofetilide
Vardenafil
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
An increased risk of QT interval prolongation
Interaction Deep Dive
In 59 healthy males, therapeutic and supratherapeutic doses of vardenafil led to similar QTc interval increases compared to the active-control moxifloxacin. Patients with congenital QT prolongation or those receiving class IA or class III antiarrhythmics should avoid using vardenafil. Due to the risk of additive QTc prolongation, the concurrent administration of vardenafil and class III antiarrhythmic agents should be avoided12.
Why it happens (mechanism)
Additive QT interval prolongation
Literature reports
1 report — tap to read
a) In a single-dose, double-blind, randomized, placebo- and active-controlled crossover study, 59 male patients receiving vardenafil 10 mg (therapeutic), vardenafil 80 mg (supratherapeutic), or moxifloxacin 400 mg experienced similar increases in QT interval measurements taken one hour after dosing. Single-dose administration resulted in a placebo-subtracted mean change from baseline QT (uncorrected) of 3 msec (90% confidence interval [CI]: 1, 5) for moxifloxacin 400 mg and -2 msec (90% CI: -4, 0) for both vardenafil 10 mg and 80 mg. Mean change from baseline Fridericia QT correction was 10 msec (90% CI: 8, 11) for vardenafil 80 mg, and 8 msec (90% CI: 6, 9) for both vardenafil 10 mg and moxifloxacin. Mean change from baseline for individual QT correction was 4 msec (90% CI: 3, 6) for vardenafil 10 mg, 6 msec (90% CI: 4, 7) for vardenafil 80 mg, and 7 msec (90% CI: 5, 8) for moxifloxacin. Mean increases in heart rate with vardenafil 10 mg and 80 mg were 5 and 6 beats per minute, respectively, compared with placebo 12.
Common questions
Can I take Dofetilide and Vardenafil together?
An increased risk of QT interval prolongation Always confirm with your pharmacist or prescriber before making any change.
How serious is the Dofetilide 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 "unspecified". The timing of this interaction is not well characterized.
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 Dofetilide 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 Dofetilide
Keep reading about Vardenafil
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:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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