Viagra tablet, VGR100

Finding the right Viagra dosage can take a little time but the potential benefits definitely make it worthwhile. You might start on the 50mg sildenafil dose but other dosages are available. 

But if you’re using the standard sildenafil dosage for ED and don’t feel like you’re quite realising your “erectile potential,” then you should think about speaking to your doctor to switch it up. 

What Sildenafil dosages are there?

There are four different Sildenafil dosages prescribed for the treatment of erectile dysfunction. The different Viagra strengths give the option to raise or lower the amount of active ingredient (sildenafil citrate), depending on how your body reacts to the medication. 

Sildenafil 50mg is the middle dose and the one that most men will be introduced to. Starting here gives your clinician the opportunity to increase or decrease the dosage depending on how your body reacts to the medication. It offers a great starting point, with 74% of patients in a fixed dose study reporting improved erections when using 50mg.[1]

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Mr Craig Marsh
Mr Craig Marsh
Pharmacist Prescriber
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Last updated August 9, 2021

Sildenafil 20mg is the lowest dose of the generic tablet. For Viagra, the branded version, the lowest is 25mg (but you can get generic sildenafil in 25mg too). These dosages may be recommended if you have not tolerated Viagra 50mg well in the past, and have had unwanted side effects. If you need to reduce your dosage to 25mg then don’t be put off, because a study still found 62% of participants that used this dose reported an improvement in their erections. 

Sildenafil 100mg is the highest dosage available to treat ED. But don’t go thinking that you need the highest dose in order to have the hardest erections, because that isn’t how it works. Your clinician will want to find the lowest dose of the drug that does the job. This is to help keep the likelihood of side effects as low as possible. Your sildenafil dosage may be increased to 100mg if the lower dosage has not had the desired effect.

Why are there different Viagra dosages for ED?

What works well for you might not work well for someone else with ED. The availability of different sildenafil citrate dosages allows doctors to level up and down where required. Your own personal recommended dose of Viagra will take lots of things into account, including your past medical history and current health and medications. 

The Sildenafil 20mg and 25mg doses can be a good starting point for men over the age of 65 with other medical conditions.

Sildenafil dosages table

Sildenafil 50mg

If you’re being introduced to Viagra for the first time you’ll likely start with the sildenafil 50mg tablet. This is the median dose and is the recommended dose of Viagra for most men. 

The Viagra 50mg dose can improve erection results but, because this dosage is the midpoint, it leaves room for a dosage change to be made if required. 

It’s often referred to as the “normal Viagra dose” and that’s probably because, as we’ve mentioned, it is quite typical to start on 50mg. This is an accessible starting point for many men, where they don’t have to attend a doctor consultation. 

The 100mg dosage is never used as a starting point for men new to Viagra. There should be no need to start on the highest dosage. 

Will all men start on Sildenafil 50mg?

While Viagra 50mg tends to be the normal Viagra dose to start on, this isn’t the case for everyone. Sometimes a lower starting dose of 25mg will be suggested by a doctor. This route may be considered if you’re already taking certain medications for the treatment of kidney, liver or heart conditions, or if your previous tolerance of sildenafil citrate 50mg was low. 

What if I get side effects on the Sildenafil 50mg dose?

Some men will experience unwanted side effects[2] even on the median dose of Viagra. This sort of problem can sometimes be resolved by moving to the lower dose. When treating ED, the next dose down is 25mg. Your doctor will discuss making this change with you, so you shouldn’t try to split pills. 

Your doctor can also tweak your dose to Sildenafil 40mg, for example, by issuing the 20mg tablets in increments (so two 20mg tablets to make 40mg). But you should never go off-piste and take multiple tablets yourself, without consulting your doctor first. 

Some of the more common side effects linked to sildenafil include headache, facial flushing, a stuffy nose, visual changes or dizziness. If you experience mild side effects, you may feel that the benefits outweigh the negatives. However, if you experience more serious side effects, such as a prolonged erection (priapism) or vision loss, then you need to seek immediate medical attention.

Sildenafil 100mg

Sildenafil 100mg and Viagra 100mg contain the maximum dose of sildenafil citrate for ED. While you may think that the strongest Viagra pill is a good starting point to get your erections back on track, this isn’t the case. 

The maximum dose of Viagra isn’t prescribed to first-timers. The decision to increase the dose of sildenafil citrate to 100mg is usually suggested by a doctor, but only after the smaller dose of 50mg has been tried first. 

If you think you need a strong Viagra dose, because the lower dose hasn’t worked how you were expecting, then you should consult your prescriber.

Is Viagra 100mg more effective?

In fixed dose studies the 100mg dosage of Sildenafil was found to improve erections for 82% of patients.[1] This is slightly higher than the 50mg dosage (74%) and the 25mg dosage (62%). 

Although the 100mg tablet is more potent and the most likely to be effective in giving erectile firmness, because there’s more of the active ingredient in it, with sildenafil 100mg side effects can be more likely. And the risk of these is higher for some men than others, depending on their tolerance of the drug. 

So if a man who doesn’t need to take a dose as high as 100mg, decides to go nuclear and take 100mg, the increased side effect risk could detract from the overall effectiveness rate. (If you get cumbersome side effects on a drug, then you could say it’s less effective for you overall.) 

A man who only needs to take 50mg will keep their side effect risk low by taking the 50mg (thus enjoying a more effective use of the drug).

If you aren’t happy with your erections when taking the 50mg dosage, speak to your prescriber. 

Is 20mg Cialis equal to 100mg Viagra?

They’re the two most well known ED drugs, so it’s common for men to compare Cialis and Viagra when trying to decide what will work best for them. The strongest dose of Cialis is 20mg while the strongest Viagra pill is 100mg. Cialis contains the active ingredient tadalafil whereas Viagra contains sildenafil citrate. Both drugs are from the PDE5 inhibitors category of medications and work in the same way. 

Cialis is also generally well tolerated and has good outcome rates for patients.[3] So if your erections do not improve after you have tried Viagra, your doctor may recommend an alternative oral ED treatment, such as Cialis.

Can I take Viagra daily?

Viagra should only be taken when you’re planning to have sex within the next hour. Only one Viagra pill should be taken in a 24-hour period. 

If you’re looking for an ED pill that will cover you every day (for example if you want to have sex on a more spontaneous basis) then Cialis Daily may be a better option for you. The Cialis Daily pill allows those who take it to obtain a strong erection at any point within the 24 hours of taking it. As with all ED pills, sexual stimulation is still required for it to be effective.

Sildenafil 20mg and 25mg

The sildenafil 20mg tablet is the lowest dose of the drug prescribed to treat ED. Sildenafil 20mg or 25mg may be the initial starting dose for some men due to other ongoing health issues. 

If you’re taking medication that could alter how your body metabolizes sildenafil then the prescriber could suggest starting at Viagra 25mg. This might be the case if you’re taking alpha-blockers for high blood pressure or antiretroviral drugs for HIV.

Also, as you get older your body may be slower at getting rid of sildenafil. Therefore, those over the age of 65 years may find that a starting dose of 25mg is sufficient. However, the Viagra dosage for a 70 year old can still be increased if the drug is well tolerated.

Who should take Viagra 20mg?

Viagra 25mg is the lowest dose of the brand-name medication. It isn’t available as a 20mg tablet, but you can get the generic sildenafil tablet in 20mg doses. It’s the same drug but isn’t a blue tablet and doesn’t come in a branded box. 

Doctors sometimes use 20mg to help them build up the dosage to 40mg or 60mg if they feel finer adjustments are needed. But the 20mg dose itself may be used when a man has a medical condition that means the 50mg dose is likely to cause side effects, or has taken the 50mg dose before and experienced side effects first-hand.

How to make sure you’re using the right Viagra dosage

In order for your doctor to recommend the best dosage for you, they need to have the full picture when it comes to your medical history. This includes any past and current health conditions and medications. Make sure that you inform them if you notice any side effects or if your treatment isn’t working like it should.

How to get the most out of your dose of Viagra

Of course you want to get the best out of your ED medication. So you should follow the instructions provided by your prescriber. 

Some Viagra best-practice measures are avoiding heavy or fatty meals before you take your pill and taking it 30-60 minutes before you intend to have sex. Remember Viagra will only get you hard when it’s combined with sexual stimulation. 

Don’t split or double up on your pills unless your doctor tells you to. You should speak to your prescriber before making any changes to your dose. 


[1] Sildenafil 100mg. Summary of Product Characteristics. Electronic Medicines Compendium (eMC). (2021)  https://www.medicines.org.uk/emc/product/7124/smpc#PHARMACOLOGICAL_PROPS 

[2] Sildenafil (Viagra) for male erectile dysfunction: a meta-analysis of clinical trial reports. Moore et al. 2002. https://bmcurol.biomedcentral.com/articles/10.1186/1471-2490-2-6

[3] Efficacy and safety of Tadalafil once-a-day versus Tadalafil on-demand in patients with erectile dysfunction: A systematic review and meta analyses. Peng et al. (2017)  https://www.karger.com/Article/Fulltext/477496