Vardenafil and Flecainide: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Vardenafil
Flecainide
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
Both flecainide and vardenafil have been associated with QT interval prolongation123. Concomitant use of vardenafil with QT prolonging agents like flecainide should be avoided due to the potential for additive effects on the QT interval 23.
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 (supra-therapeutic), or moxifloxacin 400 mg experienced similar increases in QTc 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 23.
Common questions
Can I take Vardenafil and Flecainide together?
An increased risk of QT interval prolongation Always confirm with your pharmacist or prescriber before making any change.
How serious is the Vardenafil and Flecainide 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 Vardenafil or Flecainide 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 (3)
- Product Information: Flecainide acetate oral tablets, flecainide acetate oral tablets. Amneal Pharmaceuticals (DailyMed), Paterson, NJ, 2011. DailyMed
- 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 Flecainide
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.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist