ApprovedPDE5 inhibitor
Vardenafil
Levitra, Staxyn
Short-acting, highly selective PDE5 inhibitor. Sharper on and sharper off than tadalafil, with less visual disturbance than sildenafil.
FDA-approved
FDA-approved for erectile dysfunction. Available generically.
What it is
Vardenafil is a PDE5 inhibitor with the same core mechanism as tadalafil and sildenafil, differing in selectivity and duration.
How the three compare
| Sildenafil | Vardenafil | Tadalafil | |
|---|---|---|---|
| Half-life | ~4 h | ~4-5 h | ~17.5 h |
| Onset | 30-60 min | 30-60 min | 30-120 min |
| Food interaction | Significant - fat delays it | Moderate | Minimal |
| Daily dosing viable | No | No | Yes |
| Distinctive side effect | Blue-tinted vision (PDE6 cross-reactivity) | QT prolongation signal | Back and muscle ache |
Vardenafil's selectivity for PDE5 over PDE6 - the retinal enzyme - is higher than sildenafil's, which is why the blue-vision effect is much less common. That selectivity is its main argument.
Practical notes
- This is a situational drug. If you want continuous coverage, tadalafil's half-life is the reason it exists; vardenafil cannot do that job.
- Food matters less than with sildenafil but is not irrelevant - a heavy fatty meal still delays onset.
- The QT signal is the reason to check your other medications. Combined with other QT-prolonging drugs, or in known long QT syndrome, another agent is the better choice.
- Nitrates, absolutely not. Same as the rest of the class.
Side effects and warning signs
Commonly reported
- Headache
- Flushing
- Nasal congestion
- Indigestion
- Dizziness from blood pressure reduction
Stop and get medical help
- Erection lasting over 4 hours - priapism is an emergency
- Sudden vision or hearing loss
- QT interval prolongation - vardenafil carries more of this signal than the other PDE5 inhibitors, which matters if you take other QT-prolonging drugs or have a known conduction abnormality
- Absolute contraindication with nitrates, including poppers