Viagra Dosage

How to Choose the Right Strength of Viagra

Viagra (sildenafil) is a medication for erectile dysfunction that can help you to get and keep an erection. It works by relaxing your blood vessels and increasing the blood flow to your penis.

There are three different doses of Viagra: 25mg, 50mg, and 100mg. The normal starting dose for Viagra is 50mg, but you can switch doses with the help of a doctor if you need to.

Read on for more information about the different doses of Viagra, and find out what the right dose for you is.

"The standard starting dosage for Viagra is 50mg. If this dosage doesn't work for you, you can ask your doctor whether you can try 100mg tablets."

dr zenon andreou medical director
Dr Zenon Andreou Medical Director
Dr Babak Ashrafi Clinical Lead for Service Development

Medically reviewed by

Dr Babak Ashrafi

Last reviewed: 23 Dec 2020

What Are the Doses of Viagra?

Viagra is available in three doses in the UK. 50mg is the standard dose, 25mg is the lowest dose, and 100mg is the highest.

The dosage refers to how much of the active ingredient (sildenafil citrate) is in the tablet. 1mg is the same as 0.1g, so the amount of active ingredient in a Viagra tablet is quite small, but that’s all that’s needed for it to work safely for most men.

More about Viagra 50mg

This is the standard starting dose of Viagra, and is usually what a doctor will recommend if you’ve never tried Viagra before. Viagra 50mg is effective and safe for most men to take, and is the most commonly-used dosage. This is also the only dose you can buy over the counter in the UK.

More about Viagra 25mg

This is the lowest dose available. 25mg is slightly less effective than 50mg and 100mg, but has the lowest risk of side effects and interactions with other medications. A doctor may recommend this dosage if you tried Viagra 50mg and found that it worked for you, but you also had mild side effects. You may also start on this dose if you have health conditions that make higher doses less safe, such as high blood pressure, or if you’re taking medications that could interact with Viagra.

More about Viagra 100mg

This is the highest dose of Viagra. Viagra 100mg is the most effective dosage, but it also has the greatest risk of side effects. You may want to try Viagra 100mg if the standard 50mg dose didn’t work well enough for you, but you didn’t get any serious side effects.

The maximum daily dosage of Viagra

100mg is the maximum daily dose of Viagra. You should never take more than 100mg in one day. Even if you’re on a lower dose, you should still only take one tablet a day and talk to a doctor first before increasing your dose. Taking more Viagra than you have been prescribed can be unsafe.

You should also not combine Viagra with other erectile dysfunction medications because this can cause serious side effects.

How to Pick the Right Dose for You

Which dose to start with

  • If you haven’t tried Viagra before then you’d normally start on 50mg of Viagra. This is a good dose for most men to see the effect they want while still having a low chance of Viagra side effects.
  • In some cases, depending on your health or other medications, a doctor might only recommend 25mg, even to start with. This is because higher doses might not be as safe for you.

How to switch doses

  • If you’ve tried Viagra 50mg before and it didn’t work then you might be able to increase your dose to 100mg, as long as you didn’t get any side effects. 100mg of Viagra could work for you where 50mg didn’t, but it also has a higher chance of giving you side effects.
  • If you tried Viagra 50mg and you got side effects, but you’re happy with the improvements to your erections, then you could move down to 25mg.
  • If you’ve tried 100mg and it still doesn’t work then you might need to look at alternative treatments
  • If you’ve tried 25mg and you’re still getting side effects you can’t put up with, then you also might need to look at alternative treatments

Which dosage works the fastest

On average across all three doses, Viagra takes 30 minutes to 1 hour to start working. Higher doses take slightly longer to reach their maximum strength inside your body, but this difference is fairly small.

If you want a treatment that works noticeably faster than Viagra, you could try Spedra. Spedra gets to work as fast as 15mins after you take it. You could also try Cialis Daily which you take once a day instead of before sex. Since you take it every day it’s always working so there’s no time to wait before having sex.

Which dosage has the least side effects

Overall, Viagra gives side effects to less than 2% of men who use it, though this can change depending on the dose. Below you can see the chance of getting a specific side effect, and how different dosages can affect this.

25mg of Viagra has the lowest chance of side effects, but any dose of Viagra should be safe for you as long as a doctor has prescribed it. See our pages on Viagra Side Effects for more information.

Which is best for a certain age

You shouldn't pick your dose based on age. A doctor will let you know if you need a lower dose for safety reasons, which is more likely as you get older but varies on a person to person basis. As you get older your body gets less efficient at removing Viagra from your system, so your dose may last longer. But, as you get older, your erectile dysfunction symptoms may get worse so a higher dosage might be needed.

Since there's a lot of different factors that affect age and Viagra dosage, the best thing to do is order 50mg if it's your first time and your doctor will let you know if you need a different dose.

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Doses of Generic Viagra

The doses of Sildenafil (generic Viagra) are exactly the same. You can get 25mg, 50mg, and 100mg Sildenafil and they work the same way. 50mg is the standard starting dose for most people and you can change doses with help from a doctor if you need to.

Over the Counter Doses of Viagra

Currently the only dose of Viagra available over the counter in the UK is 50mg, which is available as Viagra Connect. Other doses may become available over the counter in the future.You can buy all doses of Viagra online without having to see a doctor or pharmacist face-to-face.

How to Get the Most Out of Your Dose of Viagra

No matter which dose you’re taking, there’s a few things you can do to make sure your treatment is as safe and effective as possible:

  • Try and be as accurate as possible when giving health information to your doctor when you order Viagra
  • Read the patient information leaflet that comes with your Viagra
  • Take your Viagra as instructed by your doctor
  • Take your Viagra at least an hour before you want to have sex, to give it time to kick in
  • Try to not to eat a heavy meal before taking Viagra
  • Try not to drink alcohol with your Viagra since this makes it less effective and makes side effects more likely
  • Avoid grapefruit juice since this also makes side effects more likely
  • Avoid recreational or illegal drugs, especially amyl nitrates (poppers) since these can cause serious side effects
  • Make sure you’re relaxed and aroused when you want to have sex
  • Be aware that it can take a few doses before you see the full effect of Viagra so you might want to take in on a few different days by yourself before you try it with a partner
  • Patient Reviews