Sildenafil vs Vardenafil: Which May Suit You?

Sildenafil vs Vardenafil: A Balanced Comparison for Erectile Dysfunction

Published: 17 October 2026

When comparing sildenafil vs vardenafil for erectile dysfunction (ED), both are effective PDE5 inhibitors that help men achieve and maintain an erection when sexually aroused [3][5]. Sildenafil (the active ingredient in Viagra) and vardenafil (the active ingredient in Levitra) work in similar ways but differ in how quickly they start working, how long they last, and how food affects them. This guide compares the two medicines to help you understand which might be more suitable for your needs, though the final choice should always be made with a UK prescriber after a clinical assessment.

How Sildenafil vs Vardenafil Work in the Body

Both sildenafil and vardenafil belong to a class of medicines called phosphodiesterase type 5 (PDE5) inhibitors [3][5]. They work by relaxing the blood vessels in the penis, allowing increased blood flow when you are sexually stimulated. Neither medicine will cause an erection on its own—sexual arousal is essential for them to work [1].

The key difference lies in their chemical structure, which affects how your body absorbs and processes each medicine. Vardenafil is often described as more selective for the PDE5 enzyme, which in theory might mean fewer effects on other enzymes in the body, though both medicines have been used safely by millions of men worldwide [5][3].

In clinical practice, both medicines have similar success rates in helping men with ED achieve erections firm enough for sexual intercourse [9]. The choice between them often comes down to practical factors such as timing, meal planning, and individual response, rather than one being universally more effective than the other.

Onset Time: How Quickly Do Sildenafil and Vardenafil Work?

Sildenafil typically starts working about 60 minutes after you take it, though some men notice effects within 30 minutes [3]. For best results, it is usually recommended to take sildenafil about one hour before you plan to have sex. The medicine reaches peak levels in your bloodstream around this time, making it most effective.

Vardenafil generally works a little faster, with effects often noticed within 25 to 60 minutes [5]. Many men find that vardenafil starts working closer to the 25–30 minute mark, which can offer slightly more spontaneity compared to sildenafil. However, individual responses vary, and some men may not notice a significant difference in onset time between the two.

Neither medicine should be taken more than once in a 24-hour period [3][5]. If you are planning sexual activity, it is worth considering your schedule: sildenafil may require a bit more advance planning, while vardenafil's potentially quicker onset might suit those who prefer less waiting time.

Planning Around Onset Times

If spontaneity is important to you, vardenafil's slightly faster onset may be an advantage. However, if you are comfortable planning an hour ahead, sildenafil works just as effectively. Both medicines require sexual stimulation to work, so the timing should fit naturally into your intimate moments rather than feeling rushed or forced [1].

Duration of Action: How Long Do the Effects Last?

Sildenafil's effects typically last for around four to six hours after taking the tablet [3]. This does not mean you will have an erection for that entire time—rather, it means the medicine remains active in your system, allowing you to achieve an erection when sexually aroused during that window. After about four to six hours, the effects gradually wear off.

Vardenafil has a similar duration of action, also lasting around four to five hours [5]. In practical terms, both medicines offer a comparable window of opportunity for sexual activity. Neither is designed to provide the extended 36-hour window that tadalafil (Cialis) offers, so if you are looking for a longer-lasting option, tadalafil might be worth discussing with your prescriber [4].

For many men, a four-to-six-hour window is more than sufficient for planned sexual activity. Both sildenafil and vardenafil allow for one or more attempts at intercourse within that timeframe, provided you remain sexually stimulated. If the effects wear off and you wish to take another dose, you must wait at least 24 hours [3][5].

Food and Alcohol: How Meals Affect Sildenafil vs Vardenafil

Food can significantly affect how well sildenafil works. A high-fat meal (such as a large burger, chips, or a rich curry) can delay the absorption of sildenafil, meaning it takes longer to start working and may be less effective [3]. For best results, sildenafil is often taken on an empty stomach or after a light meal. If you have eaten a heavy meal, you may need to wait longer for the medicine to take effect.

Vardenafil is less affected by food than sildenafil, though a very high-fat meal can still slow its absorption slightly [5]. Many men find vardenafil more forgiving if they have eaten before taking it, which can be an advantage if you prefer not to plan meals around your medication. That said, taking vardenafil on an empty stomach or after a light meal is still ideal for the fastest and most reliable effect.

Alcohol can make erectile dysfunction worse and adds to the blood-pressure-lowering effects of both medicines, potentially causing dizziness or light-headedness [3][5]. A small amount of alcohol (one or two units) is unlikely to cause problems for most men, but heavy drinking is best avoided when using either sildenafil or vardenafil. If you are unsure how much is safe, discuss it with your prescriber during your consultation.

Practical Meal Planning

If you often eat larger meals in the evening and prefer not to adjust your routine, vardenafil's reduced sensitivity to food may make it a more convenient choice. If you are happy to take your tablet on an empty stomach or after a light snack, sildenafil works just as well and is often more affordable [3][5].

Available Strengths and Dosing for Sildenafil vs Vardenafil

Sildenafil is available in three strengths: 25 mg, 50 mg, and 100 mg [3]. The usual starting dose is 50 mg, taken about one hour before sexual activity. Depending on how well it works and whether you experience side effects, your prescriber may adjust the dose to 25 mg (if side effects are troublesome) or 100 mg (if 50 mg is not effective enough). The maximum dose is 100 mg, and it should not be taken more than once a day.

Vardenafil is available in 5 mg, 10 mg, and 20 mg strengths [5]. The usual starting dose is 10 mg, taken about 25 to 60 minutes before sex. Your prescriber may lower the dose to 5 mg if you experience side effects, or increase it to 20 mg if needed. Like sildenafil, vardenafil should only be taken once in a 24-hour period, and the maximum dose is 20 mg.

Both medicines are prescription-only, meaning you will need a consultation with a UK prescriber before you can obtain them [1][2]. At Cured Pharmacy, our online consultation is reviewed by a UK-registered prescriber who will recommend the most appropriate starting dose based on your health, other medicines, and individual circumstances. The dose can be adjusted over time if needed.

Side Effects, Safety, and Who Each Medicine May Suit

Common side effects of both sildenafil and vardenafil include headache, flushing (redness or warmth in the face and neck), indigestion, nasal congestion, and dizziness [3][5]. These effects are usually mild and temporary, often improving as your body adjusts to the medicine. Vardenafil may cause slightly less visual disturbance (such as a blue tinge to vision) compared to sildenafil, though this side effect is uncommon with either medicine.

Both medicines are contraindicated if you take nitrates (such as GTN spray or isosorbide mononitrate), nicorandil, riociguat, or recreational drugs known as 'poppers', because the combination can cause a dangerous drop in blood pressure [3][5]. If you take alpha-blockers for prostate symptoms or blood pressure (such as tamsulosin or doxazosin), you must be stable on that medicine before starting a PDE5 inhibitor, and your prescriber will usually recommend the lowest dose to start. Potent CYP3A4 inhibitors (such as ritonavir, ketoconazole, or clarithromycin) can raise levels of both medicines, requiring dose adjustments or avoidance—your prescriber will check all your current medicines during the consultation [3][5].

Sildenafil may suit you if you prefer a well-established, widely used medicine with a lower cost, especially if you are comfortable planning around meals and waiting about an hour for it to work. Vardenafil may be a better fit if you value a slightly faster onset, less interference from food, or if you have tried sildenafil and found it less suitable. Neither medicine is universally better—the right choice depends on your lifestyle, preferences, and how your body responds. If you are new to ED treatment, seeing your GP is important, as erectile dysfunction can be an early warning sign of heart disease or diabetes [1][2].

When to Seek Urgent Help

If you experience an erection lasting more than four hours (priapism), sudden loss of vision or hearing, or chest pain during sex, seek urgent medical help immediately [3][5]. These are rare but serious side effects that require prompt treatment. If you feel unwell or have concerns about side effects, contact your GP or pharmacist for advice.

Scientific References

1. NHS. (n.d.). Erectile dysfunction (impotence). NHS website. https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/ [accessed 17 October 2026]
2. National Institute for Health and Care Excellence. (n.d.). Erectile dysfunction. Clinical Knowledge Summaries. https://cks.nice.org.uk/topics/erectile-dysfunction/ [accessed 17 October 2026]
3. Joint Formulary Committee. (n.d.). Sildenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/sildenafil/ [accessed 17 October 2026]
4. Joint Formulary Committee. (n.d.). Tadalafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/tadalafil/ [accessed 17 October 2026]
5. Joint Formulary Committee. (n.d.). Vardenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/vardenafil/ [accessed 17 October 2026]
6. Goldstein, I., Lue, T. F., Padma-Nathan, H., Rosen, R. C., Steers, W. D., & Wicker, P. A. (1998). Oral sildenafil in the treatment of erectile dysfunction. New England Journal of Medicine, 338(20), 1397–1404. https://pubmed.ncbi.nlm.nih.gov/9580646/ [accessed 17 October 2026]

Information on this page is for educational purposes only and is not medical advice. Prescription treatments require clinical assessment by a UK-registered prescriber. Always consult a qualified healthcare professional before starting or changing any medication.