How Does Vardenafil Work for Erectile Dysfunction?

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Key takeaways

• Vardenafil blocks the PDE5 enzyme, improving blood flow to the penis during sexual arousal.
• It typically works within 25 to 60 minutes and lasts around four to five hours.
• Sexual stimulation is needed—vardenafil does not cause an automatic erection.
• Never take vardenafil with nitrates, nicorandil, poppers, or another PDE5 inhibitor.
• All ED medicines at Cured Pharmacy require a prescription after an online consultation.

The Science Behind How Vardenafil Works

To understand how does vardenafil work, it helps to know what happens during a normal erection. When you become sexually aroused, nerve signals trigger the release of nitric oxide in the penis. Nitric oxide activates an enzyme that produces cyclic guanosine monophosphate (cGMP), a chemical messenger that relaxes the smooth muscle in the blood vessels of the penis [5]. This relaxation allows blood to flow in, filling the spongy erectile tissue and causing an erection.

After ejaculation or when arousal fades, another enzyme called phosphodiesterase type 5 (PDE5) breaks down cGMP, allowing the blood vessels to constrict again and the erection to subside. In men with erectile dysfunction, this process does not work efficiently. Vardenafil blocks PDE5, preventing it from breaking down cGMP too quickly [5]. This means cGMP levels stay higher for longer, blood vessels remain relaxed, and blood flow to the penis is improved—making it easier to get and keep an erection when sexually stimulated.

It is important to note that vardenafil does not create sexual desire or cause an erection on its own. Sexual stimulation is still needed to trigger the release of nitric oxide and start the chain of events. Vardenafil simply enhances the body's natural response to arousal [5].

How Quickly Does Vardenafil Work and How Long Does It Last?

Vardenafil typically starts to work within 25 to 60 minutes of taking a tablet, though some men may notice effects sooner [5]. For best results, it is usually taken about an hour before you plan to have sex. Taking vardenafil on an empty stomach may help it work a little faster, as a high-fat meal can delay absorption [12].

The effects of vardenafil can last for around four to five hours, during which time it may be easier to achieve an erection if you are sexually aroused [5]. This does not mean you will have an erection for the entire duration—only that the medicine is active in your system and can help when you need it. You should not take vardenafil more than once in a 24-hour period.

Vardenafil is available in three strengths: 5 mg, 10 mg, and 20 mg. The usual starting dose is 10 mg, taken as needed before sexual activity [5]. Your prescriber may adjust the dose depending on how well it works for you and whether you experience any side effects. Always follow the dose recommended by your prescriber and do not take more than prescribed.

Factors That Can Affect How Vardenafil Works

Several factors can influence how well vardenafil works. Heavy alcohol can impair your ability to get an erection and may increase the risk of side effects such as dizziness or low blood pressure [5]. Grapefruit juice can raise the level of vardenafil in your blood, potentially increasing side effects, so it is best avoided [12].

Certain medicines can interact with vardenafil. Potent CYP3A4 inhibitors—such as ritonavir, cobicistat, ketoconazole, itraconazole, and clarithromycin—can significantly increase vardenafil levels, and vardenafil is contraindicated or should be avoided with these medicines [5][12]. CYP3A4 inducers like rifampicin, carbamazepine, phenytoin, and St John's wort can reduce vardenafil's effectiveness [5]. Your prescriber will review all your current medicines during the online consultation to check for interactions.

At a glance

Who Can Take Vardenafil and Who Should Avoid It?

Vardenafil is a prescription-only medicine in the UK, so it is only supplied after an online consultation reviewed by a UK-registered prescriber. It may be suitable for adult men with erectile dysfunction, but it is not appropriate for everyone [5].

You must not take vardenafil if you are using nitrate medicines for angina (such as GTN spray, isosorbide mononitrate, or isosorbide dinitrate), nicorandil, riociguat, or recreational drugs known as 'poppers' (amyl or alkyl nitrites). Combining vardenafil with any of these can cause a dangerous drop in blood pressure [5]. You also should not take vardenafil alongside another PDE5 inhibitor such as sildenafil, tadalafil, or avanafil.

Vardenafil is not suitable if you have had a recent heart attack or stroke, unstable angina, severe heart failure, very low blood pressure, or a previous episode of non-arteritic anterior ischaemic optic neuropathy (NAION), a rare form of sudden vision loss [5][12]. Men with certain inherited retinal disorders should also avoid vardenafil. If you take alpha-blockers for an enlarged prostate or high blood pressure (such as doxazosin, tamsulosin, or alfuzosin), you may still be able to use vardenafil, but you must be stable on the alpha-blocker and start on the lowest dose of vardenafil, as the combination can cause dizziness or low blood pressure [5]. Your prescriber will assess your medical history and current medicines to ensure vardenafil is safe for you.

How Does Vardenafil Compare to Other ED Treatments?

Vardenafil is one of four PDE5 inhibitors licensed in the UK for erectile dysfunction. The others are sildenafil (Viagra), tadalafil (Cialis), and avanafil (Spedra) [1][2]. All four work by the same basic mechanism—blocking PDE5 to improve blood flow to the penis—but they differ in how quickly they start to work and how long their effects last.

Sildenafil typically takes about an hour to work and lasts for around four to five hours [3]. Vardenafil has a similar onset and duration, though some men find it works slightly faster [5]. Tadalafil is longer-acting, with effects that can last up to 36 hours, and can be taken as a lower daily dose for continuous effect [4]. Avanafil is the fastest-acting, often working within 15 to 30 minutes [6][11].

There is no single 'best' ED medicine—what works well for one person may not suit another. Some men prefer the flexibility of tadalafil's longer window, while others like the quicker onset of avanafil or the familiarity of sildenafil. Vardenafil may be a good option if you want something that works relatively quickly and does not stay in your system for as long as tadalafil. Your prescriber can help you choose the most appropriate treatment based on your lifestyle, other medicines, and any side effects you experience.

Choosing Between Vardenafil and Other PDE5 Inhibitors

When deciding between vardenafil and other PDE5 inhibitors, consider how spontaneous you want to be and how your body responds to each medicine. If you prefer to plan ahead and want a longer window of opportunity, tadalafil may be more suitable. If you want a faster onset, avanafil might be a better choice. Vardenafil sits in the middle, offering a balance of relatively quick action and a moderate duration.

Cost can also be a factor. At Cured Pharmacy, generic sildenafil starts from £0.45 per tablet (£0.36 with code Ednew on your first order), while vardenafil is priced at £16.95 (£13.56 with code Ednew). Tadalafil is £7.95 (£6.36 with code Ednew), and avanafil (Spedra) is £20.95 (£16.76 with code Ednew). All require a prescription following an online consultation with a UK prescriber.

Common Side Effects and What to Expect When Taking Vardenafil

Like all medicines, vardenafil can cause side effects, although not everyone experiences them. The most common side effects include headache, flushing (redness and warmth in the face or chest), nasal congestion, indigestion, and dizziness [5][12]. These are usually mild and short-lived, often improving as your body adjusts to the medicine.

Less common side effects include back pain, muscle aches, nausea, and visual disturbances such as blurred vision or increased sensitivity to light [5]. If you experience any visual changes, stop taking vardenafil and seek medical advice. Rarely, vardenafil can cause a sudden decrease or loss of vision in one or both eyes, which may be a sign of NAION. If this happens, stop taking the medicine immediately and contact a doctor urgently [5][12].

Another rare but serious side effect is priapism—a painful erection lasting more than four hours. Priapism requires emergency treatment to prevent permanent damage to the penis, so if your erection lasts longer than four hours, go to A&E straight away [5]. Sudden loss of hearing or ringing in the ears has also been reported rarely; if this occurs, stop taking vardenafil and seek medical advice. If you experience chest pain during or after sex, do not use nitrates to treat it—tell the doctor you have taken vardenafil [5].

Practical Tips for Using Vardenafil Safely and Effectively

To get the most benefit from vardenafil, take it about an hour before you plan to have sex, though it may work sooner [5]. Swallow the tablet whole with water—do not crush or chew it. You can take vardenafil with or without food, but a heavy, high-fat meal may delay how quickly it works [12].

Do not take more than one dose in 24 hours, and do not increase your dose without speaking to your prescriber. If vardenafil does not work the first time, it may be more effective on subsequent attempts, as some men need to try it several times before seeing the full benefit [2]. If it still does not work after several attempts, contact your prescriber to discuss adjusting the dose or trying a different medicine.

Avoid drinking large amounts of alcohol when taking vardenafil, as this can make it harder to get an erection and increase the risk of side effects such as dizziness or low blood pressure [5]. Do not use vardenafil recreationally or share it with others—it is a prescription medicine that should only be used under medical supervision. If you have any concerns or experience side effects, speak to your prescriber or pharmacist. Erectile dysfunction can be an early warning sign of underlying health conditions such as heart disease or diabetes, so if you have not already done so, see your GP for a full health check [1][2].

When to Seek Further Medical Advice

If vardenafil does not improve your erections after several attempts, or if your erectile dysfunction suddenly gets worse, see your GP. Erectile dysfunction can be caused by physical conditions (such as diabetes, high blood pressure, or narrowed blood vessels), psychological factors (such as stress, anxiety, or depression), or a combination of both [1][10]. Your GP can investigate the underlying cause and recommend appropriate treatment, which may include lifestyle changes, counselling, or addressing other health conditions.

You should also seek medical advice if you develop new symptoms such as chest pain, shortness of breath, or palpitations, or if you have concerns about your heart health. Sexual activity places extra strain on the heart, so it is important to ensure you are fit enough for sex before using any ED medicine [2][5]. Your prescriber will assess your cardiovascular health during the consultation, but if your health changes, let them know.

When to get urgent help

• Erection lasting more than 4 hours (priapism)—go to A&E immediately to prevent permanent damage.
• Sudden loss of vision in one or both eyes—stop vardenafil and seek urgent medical advice.
• Chest pain during or after sex—do not use nitrates; tell the doctor you have taken vardenafil.
• Sudden loss of hearing or severe dizziness—stop the medicine and contact a doctor the same day.
• Severe allergic reaction (swelling of face, lips, tongue, or difficulty breathing)—call 999.

Call 999 or go to A&E in an emergency, or contact NHS 111 for urgent advice.

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