What Are the Doses of Sildenafil?

Dr Nicholas Antonakopoulos

Medically reviewed by

Dr Nicholas Antonakopoulos

Last reviewed: 12 Mar 2019

How to pick the right dose for you

Pack of Sildenafil 50mg dosage

Key takeaways

  • There are 3 doses of Sildenafil available; 25mg, 50mg, and 100mg

  • Higher doses can increase the chance of success but lower doses have less risk of side effects

  • There are things that can affect the way your Sildenafil dose works

  • Combining your dosage with non-medical treatments can give better results

  • You can't easily compare Sildenafil doses with doses of other medications

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If you’re considering getting Sildenafil treatment, or you’re already on it, you may want to know which dosage is right for you. The right dosage can improve your chance of success or help you avoid side effects.

There are also extra things to consider to get the most out of your treatment.

What are the doses of Sildenafil?

Sildenafil is available in 3 doses:

  • The most commonly recommended starting dose is 50mg
  • The dose can be increased to 100mg - if the desired effect of the 50mg is not strong enough for you
  • It can be decreased to 25mg - if you experience unwanted side effects from the 50mg dose

How will I know which dose I need? – a doctor will be able to tell you after an assessment. The dose that you're prescribed will depend on age, gender, medical condition, and use of any other medication that may interact.

Is Sildenafil stronger than Viagra? – because these medications have the same active ingredient, Sildenafil, prescribed doses are the same as Viagra prescribed doses. You can get each of them in all three doses. New Viagra Connect is only available in the 50mg dosage right now.

How does dosage affect treatment?

  • Increasing the dose of Sildenafil can increase the chance of success but increases the risk of side effects
  • Decreasing the dose of Sildenafil decreases the chance of success but also decreases the risk of side effects

Taking too much (overdosing) on Sildenafil can be dangerous – this is because it can increase the risk of various unwanted side effects without any increase in the desired effects. The unwanted side effects of overdosing can include:

  • Prolonged erections (priapism) – if the prolonged erection is not treated within 24 hours the penis may become permanently damaged, leading to possible difficulties achieving an erection in the future
  • Nausea
  • Chest pains
  • Irregular heartbeat

It is important to take your medication exactly as it was prescribed to you by your doctor.

What can affect the dosage of Sildenafil?

Taking it for the first time – Sildenafil may take a few doses to be fully effective. As long as you don’t have troublesome side effects, we recommend trying Sildenafil a few times before deciding if it’s worked for you.

Don't start or change your dose of Sildenafil tablets without discussing it with your doctor.

Heavy meals – Sildenafil works best when taken on an empty stomach. If you have just eaten a meal, Sildenafil will take longer to absorb into your system, and in turn take longer to work.

Vomiting or diarrhoea – if you experience vomiting or diarrhoea within an hour of taking Sildenafil, the Sildenafil may have not been absorbed into your bloodstream. You still need to wait 24 hours until your next dose is due rather than taking another dose, which could otherwise lead to taking too much. If vomiting or diarrhoea continues, please consult your doctor.

Grapefruit juice – try to avoid drinking grapefruit juice while taking Sildenafil, because the interaction between Sildenafil and grapefruit juice can cause unwanted side effects and it tends to delay sildenafil absorption.

Drinking – alcohol can affect your Sildenafil treatment. Drinking more than 2 to 3 units might have a negative effect on your sexual function because it can stop Sildenafil working effectively. It may also make your problems with erectile dysfunction worse – making erections less likely.

Drug use – you should avoid amyl nitrates (poppers) when taking Sildenafil as these can interact with Sildenafil and may cause potentially serious side effects.

Other drugs can affect Sildenafil – such as:

  • Alpha blockers (doxazosin, prazosin, terazosin)
  • HIV drugs (ritonavir, saquinavir, delavirdine)
  • St John's Wort
  • Cimetidine
  • Anticonvulsants (carbamazepine, phenobarbital, phenytoin)
  • Azole antifungals
  • Macrolide antibiotics (erythromycin, rifamycins)

Resistance – over time, some people feel they get less effect from Sildenafil. Please consult your doctor if you feel you are no longer experiencing the full effect of your Sildenafil dosage, it may mean your dosage needs to be increased.

How can you increase the effects of Sildenafil?

Sildenafil effects can be increased when combined with other factors:

  • Making certain lifestyle changes – for example, eating a healthy diet, having a low to moderate intake of alcohol (2-3 units per week), and increasing your exercise regime – can have a positive impact on your Sildenafil treatment.
  • Counselling – between 10 and 20% of all cases of ED have psychological causes, which can include stress, performance anxiety, and depression. Combining Sildenafil with counselling – the most effective being cognitive behaviour therapy (CBT) – can have positive results.
  • Pelvic floor exercises – exercises that strengthen the muscles and blood flow around your penis have also been shown to improve erectile dysfunction. These can be done safely with medications like Sildenafil

The most effective combination could be a treatment of Sildenafil, significant lifestyle changes, and a course of CBT from a qualified counsellor.

Do other medications have a higher dosage?

Yes but that doesn’t mean they’re stronger – different medications have different measurements of dosages. When medication with different active ingredients have different amounts of mg dosage, it does not reflect strength of medication. For example, safe Cialis dosages only go up to 20mg, whereas Sildenafil goes up to 100mg, but this doesn’t mean Sildenafil is significantly stronger than Cialis.

So medications with higher mg dosage don’t work better? – the majority of erectile dysfunction medications produce the same desired or intended results. Although some might work better for you than others, it’s not because of the dosage of their active ingredients in mg. You could try other medications if Sildenafil doesn’t work for you.

If Sildenafil doesn’t work for you at any of the doses that are safe for you, there are other options, such as:

Medically reviewed by:
Dr Nicholas Antonakopoulos

Dr Nicholas Antonakopoulos graduated from the University of London in 2006. He did his postgraduate training in hospitals in the London area, and he trained for four years in Trauma and Orthopaedic Surgery before completing his training in General practice in 2015.

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Last reviewed: 12 Mar 2019

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