Dr Ashwin Sharma

Article by Dr Ashwin Sharma

Understanding Sildenafil Dosage

Interested in trying Sildenafil for erectile dysfunction? It’s one of the most popular treatment options, helping millions of men worldwide have improved erections. Different doses work differently for different men, and it’s important you find the right one so you can get the results you want. This is our guide to each Sildenafil dose, how they differ and who they’re suitable for.

 What is Sildenafil?

Sildenafil is a medicine that belongs to a class of drugs known as PDE5 inhibitors. Its most common use is in the treatment of erectile dysfunction, but it’s also sometimes used to treat pulmonary arterial hypertension (high blood pressure in the blood vessels around your lungs). Sildenafil is also the active ingredient in the well known brand-name drug Viagra

 How does Sildenafil treat erectile dysfunction?

Sildenafil and other PDE5 inhibitors treat erectile dysfunction by encouraging smooth muscle relaxation and increasing blood flow to the blood vessels of your penis during sexual stimulation. This makes it easier to get and maintain erections when you’re aroused. 80% of men find that they experience improved erections when they take Sildenafil [1]. 

Which Sildenafil dosage should I take?

There are three doses of Sildenafil you can take: 25 mg, 50 mg, 100 mg. Each dose of Sildenafil works in just 30 to 60 minutes and lasts for four hours on average. Here’s a quick guide to each one:


This is the usual starting dose for erectile dysfunction treatment. Research shows that this dose is effective in almost three-quarters of men [2], but you can switch to a higher or lower dose if this one isn’t right for you. 

You should try Sildenafil 50 mg a few times, exactly as recommended, before deciding whether it works for you. If you don’t get the desired results, speak to your clinical team about switching to the higher 100 mg dose or a different drug, such as Tadalafil


25 mg is the lowest Sildenafil dose. You may be prescribed it if you take other prescription drugs to reduce the risk of drug interactions or adverse effects. This dose may also be for you if you experienced side effects with the 50 mg dose. If you feel like you need to increase your dose, speak to your clinical team to see if it’s safe to take a higher strength. 


This is the maximum dose of Sildenafil. Mild side effects are more likely with this dose. If you try 100 mg and still don’t have don’t have improved erections, you should speak to your doctor to explore other treatment options.

 How to take Sildenafil 

Every dose of Sildenafil takes the same amount of time to start working. We recommend taking one pill around 30 to 60 minutes before you plan to have sex to give your body plenty of time to absorb the medication. 

Does Sildenafil have side effects? 

Like all medications, Sildenafil can cause some side effects. These tend to be mild and, as we’ve previously mentioned, can vary in intensity based on your dosage. Common side effects include: 

  • Headaches
  • Muscle aches
  • Back pain
  • Facial flushing
  • Indigestion

Seek medical attention immediately if you notice severe adverse effects, including: chest pain, loss of vision, a sudden drop in blood pressure, seizures, prolonged or painful erection, hearing loss or an allergic reaction. 

How to get treatment for erectile dysfunction 

Sildenafil and other medications for erectile dysfunction need to be prescribed by a healthcare professional to make sure they’re the right treatment for you. 

Want to start having improved erections? Find out what treatment is suitable for you on MedExpress


  1. Goldstein I, Tseng LJ, Creanga D, Stecher V, Kaminetsky JC. Efficacy and Safety of Sildenafil by Age in Men With Erectile Dysfunction. The Journal of Sexual Medicine. 2016 May;13(5):852–9.
  2. ‌Sildenafil 100 mg film-coated tablets – Summary of Product Characteristics (SmPC) – (emc) [Internet]. www.medicines.org.uk. Available from: https://www.medicines.org.uk/emc/product/7124/smpc 
Dr Ashwin Sharma
Dr Ashwin Sharma
Dr Ashwin Sharma is a medical doctor and writer with a particular interest in health technology, artificial intelligence and medical weight loss. He completed his training at the University of Leicester and Imperial College London, and has since been exploring the intersections of medicine, technology, and communication.
Originally published June 17 2024, updated June 17 2024