Vardenafil (Levitra): Dosage, Side Effects, QT Caution and UK Access
Medical disclaimer: This article is for informational purposes only. Vardenafil is a prescription-only medicine. Always consult a qualified prescriber. In a medical emergency, call 999 or go to your nearest A&E.
Vardenafil is an MHRA-approved phosphodiesterase type 5 (PDE5) inhibitor for erectile dysfunction, licensed under the brand name Levitra. It belongs to the same drug class as sildenafil (Viagra), tadalafil (Cialis), and avanafil (Spedra) — and works through the same fundamental mechanism. However, vardenafil has a distinct pharmacological profile that makes it a valuable alternative for men who do not respond optimally to sildenafil, with one important clinical caution: QT interval prolongation. This guide covers dosage, how it compares to sildenafil and tadalafil, side effects, the QT caution, contraindications, and how to get it in the UK. For a comparison of all four medications, see: Viagra vs Cialis vs Levitra vs Stendra.
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What Is Vardenafil?
Vardenafil is a PDE5 inhibitor developed by Bayer and first licensed for ED in 2003 under the brand name Levitra. Generic vardenafil is available in the UK, though it is less widely available than generic sildenafil. Vardenafil works by blocking the PDE5 enzyme in the smooth muscle of penile blood vessels — the same mechanism as the other three MHRA-approved ED medications.
Vardenafil's receptor selectivity profile is slightly different from sildenafil's, with potentially higher potency at the PDE5 receptor. This is the pharmacological basis for the clinical observation that some men who do not respond adequately to sildenafil do respond to vardenafil.
Note on Availability
Vardenafil is less widely stocked in UK pharmacies than sildenafil or tadalafil. It is available through registered online pharmacies including Access Doctor following a clinical consultation.
Vardenafil Dosage
| Patient Group | Starting Dose | Maximum Dose | Timing |
|---|---|---|---|
| Standard (adults under 65) | 10mg | 20mg | 25–60 minutes before sexual activity |
| Men over 65 | 5mg | 20mg | 25–60 minutes before activity |
| Moderate liver impairment | 5mg | 10mg | With prescriber guidance |
| Taking CYP3A4 inhibitors | 5mg | 5mg | Do not combine with potent inhibitors (ritonavir) |
Vardenafil is moderately affected by food: a high-fat meal can delay onset and reduce peak plasma concentration, though the effect is less pronounced than with sildenafil. Take on an empty stomach or after a light meal for the most predictable results. Avoid alcohol in large quantities.
How Vardenafil Compares to Sildenafil and Tadalafil
| Vardenafil (Levitra) | Sildenafil (Viagra) | Tadalafil (Cialis) | |
|---|---|---|---|
| Onset | 25–60 min | 30–60 min | 30 min |
| Duration | 4–6 hours | 4–6 hours | Up to 36 hours |
| Affected by food? | Mildly — avoid high-fat meals | Yes — significantly | No |
| Daily option? | No | No | Yes (5mg daily) |
| Visual side effects | Uncommon | More common than vardenafil | Uncommon |
| QT prolongation risk | Yes — requires cardiac screening | No significant effect | No significant effect |
| Clinical efficacy | ~80% | ~82% | ~81% |
| Generic available? | Yes (limited availability) | Yes (widely available) | Yes (widely available) |
The QT Prolongation Caution — Important
Vardenafil is the only PDE5 inhibitor that produces clinically meaningful QT interval prolongation — a slowing of electrical repolarisation in the heart that can, in predisposed individuals, trigger a potentially dangerous arrhythmia called torsades de pointes.
This does not mean vardenafil is unsafe for most men — in men with a normal cardiac history and a normal QT interval, the effect is clinically minor. However, it means vardenafil is absolutely contraindicated in:
- Men with congenital long QT syndrome
- Men taking medicines that prolong the QT interval — including certain antiarrhythmics (quinidine, amiodarone, sotalol), certain antibiotics (azithromycin, clarithromycin), antipsychotics (haloperidol, quetiapine), and others
- Men with hypokalaemia (low potassium) or hypomagnesaemia, which predispose to QT prolongation
Your prescriber will screen for QT-prolonging medications and cardiac history as part of the consultation. If you are already taking any of the medicines listed above, vardenafil is unlikely to be appropriate — tadalafil or sildenafil would be safer alternatives.
Side Effects of Vardenafil
The side effect profile of vardenafil is broadly similar to sildenafil and tadalafil, with some differences:
- Headache — most common; caused by vasodilation. Paracetamol is usually sufficient.
- Facial flushing — warmth and redness in face and chest; transient
- Nasal congestion — temporary
- Indigestion — take with a light meal
- Dizziness — stand carefully; avoid alcohol
- Visual disturbances — generally less frequent than with sildenafil
- QT prolongation — see above; relevant only in men with pre-existing cardiac or electrolyte risk
Emergency: Seek Immediate Care If
An erection lasting more than 4 hours (priapism — attend A&E immediately), sudden vision or hearing loss, chest pain, or collapse. Stop vardenafil and call 999.
Contraindications
In addition to the QT caution above, vardenafil shares the same contraindications as all PDE5 inhibitors:
- Nitrate medicines in any form (absolute contraindication — potentially fatal blood pressure drop)
- Riociguat (Adempas)
- Severe hepatic impairment
- Stroke or MI within the past 6 months
- Severe hypotension or uncontrolled hypertension
- Hereditary degenerative retinal disorder (retinitis pigmentosa)
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Frequently Asked Questions
What is the difference between vardenafil and sildenafil?
Both are PDE5 inhibitors with similar onset (25–60 min) and duration (4–6 hours). Vardenafil has a slightly different receptor selectivity profile and may work for some men who don't respond to sildenafil. The main practical difference is that vardenafil carries a QT prolongation risk requiring cardiac screening — sildenafil does not. Visual side effects are also less common with vardenafil.
Who should consider vardenafil instead of sildenafil?
Vardenafil is most useful for men who have tried sildenafil at the correct dose under good conditions (empty stomach, adequate stimulation, appropriate timing) and found it insufficiently effective. Differences in pharmacological selectivity mean some men respond better to one drug than another.
What is QT prolongation and why does it matter with vardenafil?
QT interval prolongation is a slowing of electrical repolarisation in the heart. In predisposed individuals (those with long QT syndrome or taking QT-prolonging medicines), this can trigger a dangerous arrhythmia. Vardenafil produces mild QT prolongation. For most men with a normal cardiac history it is not clinically significant, but it is an absolute contraindication in men with long QT syndrome or on QT-prolonging medicines.
Does vardenafil work for diabetic men?
Yes. As with other PDE5 inhibitors, vardenafil is effective in diabetic men, though success rates are somewhat lower than in the general ED population due to diabetic neuropathy and vasculopathy. Some men with diabetes who do not respond adequately to sildenafil may respond better to vardenafil.
How long does vardenafil take to work?
Typically 25–60 minutes. It is moderately affected by food: a high-fat meal can delay onset. Take on an empty stomach or after a light meal for the most predictable timing.
Is Levitra available in the UK without a prescription?
No. Vardenafil (Levitra) requires a prescription in all doses. Unlike sildenafil, there is no over-the-counter vardenafil product. Access Doctor's pharmacist independent prescribers can assess suitability and prescribe via a confidential online consultation.
For a comprehensive overview of erectile dysfunction — causes, symptoms, and all treatment options — visit our complete guide to erectile dysfunction.
References
- NICE. Erectile dysfunction — management. CKS 2023. cks.nice.org.uk
- MHRA. Vardenafil summary of product characteristics. medicines.org.uk/emc
- Hatzimouratidis K et al. EAU Guidelines on Sexual and Reproductive Health 2024. uroweb.org
- Bischoff E. Potency, selectivity, and consequences of nonselectivity of PDE inhibition. Int J Impot Res. 2004.
- GPhC. Standards for registered pharmacies. pharmacyregulation.org