Vardenafil vs Sildenafil: Which ED pill matches your timing, dose, and side effect comfort?

Erectile dysfunction (ED) is common, and two of the most used prescription options are vardenafil (Levitra) and sildenafil (Viagra). Both are PDE5 inhibitors that support erections during sexual activity, but they do not feel the same for everyone.

They can differ in how strong they feel, how fast they start, how long they help, and which side effects you notice.

Differences between vardenafil and sildenafil for ED

These are the points many men care about most when choosing an erectile dysfunction treatment.

• Sildenafil can start working in as little as 12 minutes but usually acts within 30 minutes. Vardenafil often starts in about 30 to 60 minutes.
• Vardenafil usually lasts about 4 to 5 hours. Sildenafil can stay effective up to 12 hours in some men, although most benefit is strongest in the first 4 hours.
• Typical dosing is different: vardenafil often starts at 10 mg (up to 20 mg), while sildenafil often starts at 50 mg (up to 100 mg). Both are taken no more than once per day for ED.
• Both can cause common side effects such as headache, flushing, and stomach upset. Rare serious risks include sudden vision loss and chest pain.
• Empty stomach often helps both work faster. Men over 65 or with certain health issues often start at lower doses.

How do vardenafil and sildenafil create an erection in the body?

To understand why these ED pills work, it helps to follow the steps your body already uses. Sexual stimulation starts the process. Your body releases nitric oxide, which raises cGMP in penile tissue. cGMP helps blood vessels and smooth muscle shift into a state that supports blood flow into the penis.

Both drugs block PDE5, the enzyme that breaks down cGMP. When PDE5 is blocked, cGMP stays active longer. That gives your body more time to produce and keep an erection during sex.

Here is how each one does that job.

Vardenafil mechanism and selectivity

Vardenafil targets phosphodiesterase type 5 (PDE5). PDE5 normally breaks down cyclic guanosine monophosphate (cGMP), which helps control blood flow.

Research shows vardenafil inhibits PDE5 very strongly, with an IC50 of 0.89 nanomolar. That number is small, so it shows only a tiny amount is needed to block the enzyme’s activity. When PDE5 stays blocked, cGMP remains active longer. Smooth muscle in the penis relaxes. Blood flow rises. An erection can happen.

Sexual stimulation still matters. Why? Stimulation triggers nitric oxide release. Nitric oxide starts cGMP production. Without nitric oxide, the drug has little to work with, so you should not expect an automatic erection.

Vardenafil is also highly selective. One study found it had a safety margin of over 33,000 times compared with other enzymes. This high selectivity means it is strongly targeted, which can reduce side effects linked to hitting the wrong enzyme.

Sildenafil competitive inhibition and muscle effects

Sildenafil works in a similar way, but it is often explained as competitive inhibition. Sildenafil mimics the shape of cGMP and competes at the spot where PDE5 would normally bind and break cGMP down.

When PDE5 is blocked, cGMP builds up inside smooth muscle cells. Then cGMP activates a protein kinase. This lowers calcium levels inside the cells, encourages potassium to move out, and blocks another protein that would tighten the muscle. Smooth muscle relaxes. Blood can flow into the corpus cavernosum, which is the spongy tissue that fills during an erection.

Sildenafil also needs sexual stimulation. No stimulation means no nitric oxide release. No nitric oxide means low cGMP production. In that case, the pill will not create an erection on its own.

PDE5 is the main enzyme that breaks down cGMP in the penis. That is why inhibiting it is so effective for erectile dysfunction. Sildenafil targets PDE5 and does not cause unwanted muscle relaxation in areas like the bladder or the heart, which supports safer use for many patients.

How fast do vardenafil and sildenafil work, and how long do they last?

Timing is one of the biggest reasons men choose Levitra vs Viagra. Do you want a faster start? Do you want a longer window? Your schedule, meals, and metabolism can change what you feel.

Timing overview for ED use:

• Vardenafil onset: 15 to 60 minutes (typically about 30 to 60 minutes)
• Vardenafil duration: about 4 to 5 hours
• Sildenafil onset: 12 to 30 minutes (typically around 27 minutes)
• Sildenafil duration: strongest around 4 hours, can last 8 to 12 hours in some men

Vardenafil onset, peak levels, and real-world window

Vardenafil can act quickly. In one study, some men reached peak plasma concentrations in as little as 15 minutes after a single oral dose. Most patients reached peak levels around 0.6 to 0.9 hours, which is about 36 to 54 minutes.

The median time to reach peak concentration (Tmax) stayed under an hour across doses:

• 0.66 hours for 20 mg
• 0.68 hours for 40 mg

So when should you take it? Many men plan sexual activity 30 to 60 minutes after dosing.

How long does it last? The half-life averaged 4 to 5 hours. In practice, the effective window is often about 4 hours, with potential benefit up to 4 to 5 hours depending on the person.

One study also noted that 50% of users achieved an erection within 30 minutes after taking vardenafil. Food can change this. A high-fat meal can delay onset by about 1 hour and reduce peak concentration by 18%. This is why many instructions suggest an empty stomach for faster results.

Sildenafil onset, response rates, and extended effect

Sildenafil can also start fast. In a study of men with erectile dysfunction, the median onset of action was 27 minutes, with some men responding as early as 12 minutes after a 50 mg dose.

Response rates were strong in that study:

• 71% achieved erections within 30 minutes
• 82% responded within 45 minutes

That can feel more predictable when you want a clear start time. Still, meals can slow the start. Many men report the best speed when sildenafil is taken on an empty stomach.

What about how long it lasts? One study found sildenafil can remain effective up to 12 hours in some men, although the peak performance is usually within the first 4 hours.

The same research reported erection duration at different times after dosing.

Self-reported erection duration:

• 33 minutes at 1 hour
• 23 minutes at 8 hours
• 16 minutes at 12 hours

RigiScan measurements (erections with at least 60% rigidity):

• 26 minutes at 1 hour
• 11 minutes at 8 hours
• 8 minutes at 12 hours

Sildenafil’s plasma half-life is around 3 to 5 hours, but the clinical window can last longer than the blood level suggests. For many men, it is safest to expect the strongest response for up to 4 hours, with weaker effects that may continue up to 8 or even 12 hours depending on your body, food intake, and other factors.

Which ED pill performs better in studies for erection success and satisfaction?

Effectiveness includes successful penetration, maintaining the erection, and how satisfied men feel over time. Results can also shift when men have health issues like diabetes or hypertension.

The data below shows what studies reported for both vardenafil and sildenafil.

Vardenafil study results, including men with health conditions

In a study of European men using flexible dosing, vardenafil significantly improved erectile function. The IIEF-EF domain score moved from moderate ED levels toward milder ED, while placebo showed very little change.

Men also reported strong improvement rates:

• 80% to 86% of men on vardenafil reported improved erections
• 21% to 36% on placebo reported improved erections

Success rates for intercourse also improved:

• 84% success by weeks 8 and 12 for vardenafil users
• 49% to 53% for placebo

For maintaining an erection:

• 58% to 74% success with vardenafil
• 22% to 34% with placebo

Another study tested 20 mg vardenafil in 573 men, many with diabetes and hypertension. The results were strong even after the first dose:

• 81% achieved successful penetration after the first dose
• 70% maintained their erections after the first dose

By the end of the study, results improved further:

• 85% for penetration
• 78% for maintenance

So, vardenafil can perform consistently, including in men with common medical conditions that often make ED harder to treat.

Sildenafil long-term satisfaction and broad trial evidence

Sildenafil has strong long-term data. In a four-year study with 979 men using flexible doses, at every yearly check-in, over 94% said they were satisfied with how it worked for their erections. Nearly all men also said it helped them engage in sexual activity.

A large pooled analysis also supports sildenafil’s effectiveness. Researchers combined results from 11 double-blind, placebo-controlled trials with 2,667 men. Across IIEF scores, general questions, and patient event logs, sildenafil improved erectile function significantly more than placebo. The benefit showed up across different age groups and different causes of erectile dysfunction.

What dose should you use for vardenafil or sildenafil, and who should start lower?

Dosing is one of the easiest places to get confused, especially when you see that vardenafil doses look smaller than sildenafil doses. That does not mean one is weaker. They are measured differently, and each has its own standard range.

To set expectations, both medications for ED are typically taken as needed, and both should be taken no more than once per day.

Vardenafil (Levitra):

• Starting dose: 10 mg
• Dose range: 5 mg to 20 mg
• Maximum dose: 20 mg
• Frequency: once per day

Sildenafil (Viagra):

• Starting dose: 50 mg
• Dose range: 25 mg to 100 mg
• Maximum dose: 100 mg
• Frequency: once per day

Vardenafil dosing details, ODT rules, and who should avoid it

Vardenafil is often started at 10 mg taken orally once a day, about 60 minutes before sex. Depending on how it works and how you tolerate it, the dose can be raised to 20 mg or lowered to 5 mg. You should not take it more than once per day.

Some men should start lower:

• Men aged 65 or older often start at 5 mg as needed.
• The 5 mg start also applies to patients using alpha-blockers or those with moderate liver disease, since effects can be stronger.

In cases of severe liver dysfunction, vardenafil should be avoided.

Vardenafil also comes as an orally disintegrating tablet (ODT). The ODT version is not interchangeable with the standard film-coated tablets. If you need a dose higher or lower than 10 mg, you should use the film-coated tablets, not the ODT.

ODT use details matter:

• Take the ODT without liquid.
• Take it right after removing it from the packaging.

Also keep expectations realistic. Sexual stimulation is still required for vardenafil to work.

Sildenafil dosing for ED and for pulmonary hypertension

Sildenafil tablets for ED come in 25 mg, 50 mg, and 100 mg. The typical starting dose for most men is 50 mg taken when needed.

Timing matters:

• You can take it up to 4 hours before sexual activity.
• Many men find it works best on an empty stomach.

If needed, the dose can be raised to 100 mg or lowered to 25 mg, based on response and side effects. You must not take more than one dose per day.

Sildenafil also has a different dosing plan when used for pulmonary hypertension:

• Adults typically take 20 mg three times a day.
• For children, the dose depends on weight and ranges from 10 mg to 20 mg, also three times daily.

Sildenafil can be given as tablets or liquid. Instructions stay the same: stick to the prescribed amount, and do not double up if you miss a dose.

What side effects should you expect from vardenafil or sildenafil?

Side effects can feel like the deciding factor, especially if you already deal with headaches, reflux, or sinus issues. Most men get mild, short-lived symptoms, but a few warning signs mean you should stop and get medical help right away.

Common side effects you may notice

Both vardenafil and sildenafil can cause:

• Headache
• Flushing or warmth in the face
• Stuffy or runny nose
• Indigestion or upset stomach
• Dizziness
• Nausea

Vardenafil can also cause extra mild symptoms in some men, such as light vision changes, body aches, or feeling sleepy. Sildenafil can also cause similar mild issues, but many people mostly notice the headache and flushing.

Serious side effects that need urgent help

These are rare, but they matter. Get emergency care if you notice:

• Chest pain, tightness, or trouble breathing, especially during or after sex
• Sudden vision loss or major vision changes
• Sudden hearing loss
• Fainting, severe dizziness, or a fast or pounding heartbeat
• A painful erection that does not go away (especially if it lasts more than 2 hours)
• Signs of a severe allergy, such as swelling of the lips, mouth, throat, or tongue, or trouble swallowing

Which one fits your needs best?

• If you want a shorter, more focused window, vardenafil often fits that plan. It usually starts within 30 to 60 minutes and lasts about 4 to 5 hours.
• If you want a longer time window, sildenafil often gives more flexibility. It can start as early as 12 minutes, commonly works within 30 minutes, and may last up to 8 to 12 hours in some men, with the strongest effect in the first 4 hours.
• If you are older than 65 or have certain health issues, vardenafil often starts at 5 mg, while sildenafil often adjusts between 25 mg to 100 mg for ED depending on response and side effects.
• If side effects are your main concern, both can cause common issues like headache, flushing, and indigestion, but both also carry rare serious risks such as chest pain and sudden vision loss, so urgent symptoms should never be ignored.
• If speed matters, taking either medication on an empty stomach can help, and a high-fat meal can slow vardenafil onset by about 1 hour and lower peak concentration by 18%.