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How long does Sildenafil make you last?

10 min read time

Written by: Sunny Dhain

Medically reviewed by: Tannaz Sohrabi

Published 07/03/2024 Updated 31/07/2026

Sildenafil starts working within 30 to 60 minutes and remains effective for about 4 hours. It remains in your bloodstream for 15 to 25 hours after that. Taking a higher dose makes the effect stronger, but it doesn’t extend the window.

New to Sildenafil?

How long does Sildenafil make you last?

People ask us this in two quite different ways.

Some patients mean the time window, which is around four hours. The NHS advises that sildenafil can be taken up to 4 hours before sex, and within that window it’s easier to get and keep an erection when you’re aroused.

Other patients ask if it will prevent premature ejaculation, and the answer is no. Sildenafil is licensed for erectile dysfunction and acts on blood flow to the penis. It has no effect on ejaculatory control, and it isn’t a treatment for premature ejaculation.

Some men do notice that once the worry about losing an erection goes away, sex improves as an indirect effect of treating anxiety, not something the medicine does on its own. If finishing sooner than you want is the actual problem you’re trying to solve, it’s a different condition with different treatments. Our premature ejaculation page covers those, or you can raise it in your consultation, and we’ll talk it through.

Two things people often assume that aren’t true: sildenafil doesn’t give you a four-hour erection, and it doesn’t do anything at all without arousal. After you ejaculate, the erection subsides as it normally would.

How long do the effects last?

About four hours for most people.

It’s strongest in the first hour or two, then tails off gradually rather than switching off. Peak concentration in the blood occurs between 30 and 120 minutes after taking it on an empty stomach, which is why the middle of the window is usually the most dependable.

Four hours is an average, but averages hide a lot. Age, liver and kidney function, other medicines you’re on and whether you’ve eaten all shift it. Men over 65 and anyone whose liver isn’t clearing drugs as efficiently will often find the effect lasts longer, which is one reason a lower starting dose gets used in those groups.

One thing that isn’t a good sign: an erection lasting more than four hours. That’s priapism, and it needs emergency treatment to prevent lasting damage. Don’t wait it out.

How long does 100mg Sildenafil last?

Roughly four hours, same as 25mg and 50mg. The dose changes how strong the response is, not how long you’re covered for.

We flag this because it’s the assumption behind many of the questions we get, and most online pages either dodge it or get it wrong. What governs the duration is how fast your body clears the drug, and that doesn’t change much with dose. Starting from a higher peak means the last hour or so may feel a bit more usable, but 100mg won’t turn a four-hour medicine into an eight-hour one. If the window itself is the problem, the answer is usually a different medicine rather than more of this one. Tadalafil stays active for up to 36 hours.

Dose	25mg	50mg	100mg
Typical use	Lower starting dose, often for men over 65 or with reduced liver or kidney function	Standard starting dose for most adults	Where 50mg has been tried and the response wasn’t enough
Time to start working	30–60 minutes	30–60 minutes	30–60 minutes
Duration of effect	~4 hours	~4 hours	~4 hours
Side effect likelihood	Lowest	Moderate	Highest

The BNF sets 100mg as the maximum single dose, and the NHS makes it clear that sildenafil shouldn’t be taken more than once in 24 hours, whatever the strength. Above 100 mg, you don’t get better results; you just get more side effects. Any change of dose should come from your prescriber rather than from taking two of what you already have at home.

How long does it take to work?

Usually 30 to 60 minutes. The NHS suggests taking it 30 to 60 minutes before sex and notes you can take it as much as four hours ahead.

Four things move that timing:

Food – A heavy or fatty meal significantly slows absorption, and the NHS recommends taking it on an empty stomach for ED. A snack is fine, but a large dinner beforehand is the most common reason a dose seems to have had no effect.

Alcohol – raises the odds of headache and dizziness, and enough of it will make an erection harder to get in the first place, which rather works against the point.

Grapefruit – Grapefruit and its juice can raise sildenafil levels. Avoid both, per the FDA prescribing information.

Your own metabolism – Age, liver function and other medications all affect absorption and clearance, which is why two men on the same dose can have quite different experiences of it.

The NHS makes a related point that’s worth repeating: when sildenafil appears not to have worked, the usual explanations are not waiting long enough, or waiting too long. Give a dose several attempts before you write it off.

How long does Sildenafil stay in your system?

Longer than it works for. Around 15 to 25 hours in a healthy adult.

The half-life is about 3 to 5 hours, so the amount in your blood halves roughly every four hours. A drug is generally considered substantially cleared after about five half-lives, which is where the 15 to 25 hour figure comes from.

Time after dose	Status
30–60 minutes	Starts working
1–2 hours	Peak concentration
~4 hours	Effective window closing
~12 hours	A quarter or less remaining
15–25 hours	Substantially cleared

Clearance runs slower if you’re over 65, if your liver or kidneys aren’t working well, or if you take anything that prevents enzymes in the liver from breaking down the medication.

This means drugs like ketoconazole, erythromycin and ritonavir slow the process down and can mean a reduced starting dose is appropriate.

There are two practical consequences. It’s why the once-in-24-hours limit exists, because a second dose taken too soon is added on top of a drug that hasn’t finished clearing. And if you ever need emergency treatment for chest pain, tell the medical team when you last took it.

Nitrates given for angina can cause a dangerous drop in blood pressure alongside sildenafil, so they need to know.

Getting the most from a dose

Take it 30 to 60 minutes before sex, on an empty stomach or after something light.

Skip a large fatty meal beforehand.

No grapefruit or grapefruit juice.

Keep alcohol intake modest.

Swallow the tablet whole with water.

One dose in 24 hours, maximum.

You need to be aroused. The medicine supports the response; it doesn’t create it.

Give a new dose several times before deciding it’s wrong for you, and come back to us rather than changing it yourself.

Not sure Sildenafil is right for you?

Check your suitability with an online consultation

How it compares on duration

If four hours don’t suit you, duration is the main thing that separates these medicines.

Medicine	Time to work	Duration
Sildenafil (Viagra)	30–60 minutes	~4 hours
Tadalafil (Cialis)	30–45 minutes	Up to 36 hours, and available as a low daily dose
Vardenafil (Levitra)	30–60 minutes	Around 4–5 hours
Spedra (Avanafil)	15–30 minutes	Around 4–6 hours

The NHS notes that tadalafil, avanafil and vardenafil work in a similar way if sildenafil doesn’t suit you. There are non-drug routes as well, including vacuum devices and working on the things that contribute to ED in the first place: smoking, weight, alcohol, stress.

ED can be an early sign of cardiovascular disease or diabetes, which is a large part of why we ask the questions we ask before prescribing anything. Our erectile dysfunction and stop smoking pages go into more detail.

Ready to get started?

Frequently Asked Questions

How long does sildenafil make you last?

The window is around four hours, during which it’s easier to get and keep an erection when you’re aroused. It doesn’t delay ejaculation, and it doesn’t produce a continuous erection for that whole time.

How long does 100mg sildenafil last?

Around four hours, the same as the lower doses. A higher dose gives a stronger response, not a longer window, and it makes side effects more likely.

How long does sildenafil stay in your system?

Roughly 15 to 25 hours in a healthy adult, based on a half-life of 3 to 5 hours. Longer if you’re over 65 or your liver or kidneys are impaired.

How long does sildenafil take to work?

Typically 30 to 60 minutes. If it’s taking longer, a heavy meal beforehand is the usual culprit.

Does sildenafil keep you hard after coming?

No. The erection subsides after ejaculation as it normally would, and you’ll need further arousal for another one.

Can I take sildenafil two days in a row?

Yes, as long as it’s been prescribed for you and you keep to one dose in any 24-hour period.

Does sildenafil stop working over time?

Not in the way people worry about. The NHS says there don’t appear to be lasting harmful effects from taking it long term, and tolerance isn’t really the issue. If a dose that used to work has stopped working, come and talk to us. That often reflects a change in what’s causing the ED rather than anything to do with the medicine.

What are the common side effects?

Headache, nausea, indigestion, flushing, dizziness, and a blocked nose are the most commonly reported. Plenty of men get none, or only mild ones. The serious risk to know about is combining sildenafil with nitrates prescribed for chest pain.

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How we reviewed this article:

Sources

Sildenafil (Viagra) — About sildenafil (2026) NHS [accessed 31st July 2026]
Sildenafil (Viagra) — How and when to take sildenafil (2026) NHS [accessed 31st July 2026]
Sildenafil (Viagra) — Who can and cannot take sildenafil (2026) NHS [accessed 31st July 2026]

Current version
31st Jul 2026 Edited by: Sunny Dhain, MPharmRS PGDip IndP
31st Jul 2026 Medically reviewed by: Tannaz Sohrabi

Medically reviewed by:

Tannaz Sohrabi

Tannaz is Superintendent Pharmacist at The Family Chemist, where she leads the clinical governance and safety standards of the pharmacy and online clinic. With extensive experience across both hospital and community pharmacy, she brings a strong clinical background and a deep understanding of patient care to the service.

Last reviewed: 31st Jul 2026

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How long does Sildenafil make you last?

Content

How long does Sildenafil make you last?

How long do the effects last?

How long does 100mg Sildenafil last?

How long does it take to work?

How long does Sildenafil stay in your system?

Getting the most from a dose

How it compares on duration