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Viagra Dosage: How Much Should I Take?

Viagra Dosage: How Much Should I Take?


Written by:

Dr. Zoë Lees (PhD)

Medically reviewed by:

Dr. Sophie Dix (BSc, PhD)

Published:

17 April 2018

Updated:

21 May 2026

Reading time: 6 minutes
Viagra Dosage: How Much Viagra Should I Take?

Viagra is one of the most well known prescription drugs used to treat erectile dysfunction, used for almost 30 years to help men improve their erections.

It's important to take the right Viagra dosage for you to make sure you get the best results from it. Let’s explore the difference between Viagra doses, what the recommended starting dose is and how to take Viagra correctly.

Article Summary

  • Viagra is a prescription medication used to treat erectile dysfunction. Taking the right dose at the right time is key to getting the best results.
  • Viagra pills come in three doses: 25mg, 50mg (this is the usual starting dose) and 100mg. It should be taken 30 to 60 minutes before sex, on an empty stomach.
  • You can physically split a Viagra pill, but doing so reduces the strength of your dose by half. We don't recommend this because it’s difficult to get an exact, even dose by hand. Instead, speak to our clinical team if you’d like to adjust your next dose.

How does Viagra work?

All Viagra doses work in the same way. They all contain the active ingredient sildenafil citrate, which is a type of drug called a PDE5 inhibitor. Sildenafil helps relax the blood vessels at the base of your penis, improving blood flow and helping you get harder erections when you're aroused. [1]

Viagra doses

Viagra comes in three strengths: 25mg, 50mg, and 100mg. While all three are proven to work, the intensity of the effect increases with the dosage.

Viagra 25mg

This is the lowest dose of Viagra available. If you take other prescription medications, you may start with this dosage to avoid drug interactions. You might also find this Viagra dosage has minimal side effects, or none at all. Viagra 25mg lasts as long as the higher dosage options (four hours after you take it, on average) although the effects can be a little less noticeable.

If this dose doesn’t have the effect you want, speak to your clinical team about whether it’s safe for you to take a higher strength instead. [2]

Viagra 50mg

This is the usual starting dose for men when treating erectile dysfunction. If you find this seems too strong or too weak, your clinical team could recommend either increasing or decreasing your dose. Viagra is effective in 8 in 10 men, based on the fact that 78% experienced improved erections, so it’s likely you’ll benefit from this treatment. [3]

If you find that Viagra 50mg doesn’t work for you the first time you take it, there are a few things you can do. For example:

  • Try it on four separate occasions, taking it exactly as recommended.
  • If this doesn't work, speak to your clinician about switching to 100mg.
  • If 100mg isn’t effective, our expert clinicians will recommend a different erectile dysfunction medication, such as Cialis.

Viagra 100mg

You should take it in exactly the same way as lower doses, 30 to 60 minutes before sex and on an empty stomach. If you have to take it close to eating, make sure you avoid high-fat meals. Never take more than one tablet at a time or take more than one in a 24-hour period.

While the effects don’t last longer than the 50mg dosage, they tend to be stronger. However, side effects are also more likely when taking a larger dose.

If you don't have the desired effect after taking 100mg, you should consult your doctor to explore other options.

How much Viagra should I take the first time?

Here's how to find the right Viagra dose for you:

  • The recommended starting dose is 50mg, taken about an hour before sexual activity.
  • If 50mg works for you, but you’re experiencing side effects, your clinical team may recommend a lower dose of 25mg, or advise you stop taking Viagra completely and discuss alternative ED treatment options.
  • 100mg is the maximum Viagra dosage, prescribed when you don't get the desired results with 25mg or 50mg doses.

How long does Viagra take to work?

Your body absorbs Viagra quickly, so it usually works within 30 to 60 minutes. We recommend you take Viagra around an hour before sex, without food. If you take Viagra with a heavy meal, it absorbs more slowly, so it takes longer to work.

Viagra side effects

The most common side effects of Viagra include:

  • Headaches
  • Flushing
  • Indigestion
  • Dizziness
  • Nausea
  • Stuffy nose

All of these are mild side effects, and symptoms shouldn’t last more than a few hours.

If you experience more serious effects, like blurred vision, chest pains, sudden changes in blood pressure or an allergic reaction (your lips, mouth, throat or tongue suddenly become swollen, your throat feels tight or you're struggling to swallow) seek urgent medical attention.

Before taking Viagra it’s important to ensure you’ve discussed your full medical history with your clinical team. Other prescription drugs can interfere with Viagra, so keep your doctor informed if you're planning to take Viagra.

Can you take half a Viagra pill?

Only some sildenafil tablets can be split. Tablet splitting is only suitable for specific scored tablets that are authorised to be divided into equal halves. Not all products are suitable. for example, Viagra Connect 50 mg tablets must not be split because they are not scored.

If a tablet is approved for splitting, each half will give around half the dose (for example, a 50 mg tablet gives about 25 mg per half). However, splitting tablets isn’t perfectly precise, so the amount in each half can vary slightly. This may make the effect feel a little weaker or change side effects for some people.

Splitting a tablet does not change how long it lasts, sildenafil still works for around 4–6 hours. Lower doses usually give a milder effect. Take it 30–60 minutes before sex, as usual.

Always speak to our clinical team before splitting tablets or changing your dose. We’ll check it’s safe and appropriate for you.

Only split tablets that are authorised to be divided, and use a proper pill cutter for better accuracy. Don’t break tablets by hand or with a knife.

Keep tablets whole in their original blister and only split them when you’re ready to take a dose. This helps maintain quality and effectiveness.

Can I take Viagra with other erectile dysfunction drugs?

You should never take different ED medications together. If you do, you could cause a drug interaction and be at risk of severe side effects.

If Viagra doesn’t work for you, you may need to try a different erectile dysfunction medication e.g. tadalafil. Some lifestyle changes, like reducing alcohol intake and not smoking, can also help. If you have mental health concerns, you should speak to your GP for support or counselling. [3]

Getting the right dose makes all the difference. At MedExpress, you can complete an online consultation and access a range of erectile dysfunction treatments without an in-person appointment, including Viagra in all three strengths and Cialis for a longer-lasting option.

References

  1. Viagra: Uses, Dosage & Side Effects Information [Internet]. Drugs.com. Available from: https://www.drugs.com/viagra.html
  2. How and when to take sildenafil [Internet]. nhs.uk. 2022. Available from: https://www.nhs.uk/medicines/sildenafil-viagra/how-and-when-to-take-sildenafil/
  3. Fink HA, Mac Donald R, Rutks IR, Nelson DB, Wilt TJ. Sildenafil for male erectile dysfunction: a systematic review and meta-analysis. Arch Intern Med. 2002 Jun 24;162(12):1349-60. doi: 10.1001/archinte.162.12.1349. PMID: 12076233.
  4. NHS. Erectile dysfunction (impotence) [Internet]. NHS. 2019. Available from: https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/

Next scheduled review date: 21 May 2029

Labels
erectile dysfunction
viagra

Authors

Dr. Zoë Lees, PhD Metabolic Medicine

Written by: Dr. Zoë Lees (PhD)

Dr. Zoë Lees is a medical writer at MedExpress specialising in obesity and health communication. She completed her PhD at the University of Glasgow, where she investigated adipose tissue (fat tissue) function in pregnancies complicated by pre-eclampsia and gestational diabetes. Her work focuses on translating complex clinical evidence into clear, engaging and evidence-based health information for patients and the public. At MedExpress, Zoë contributes to clinical content, educational resources and media communications across areas including weight management, GLP-1 therapies and metabolic disease. Zoë is particularly interested in improving public understanding of obesity as a chronic condition and ensuring patients have access to accurate, accessible health information grounded in current scientific evidence.

Dr. Sophie Dix

Medically reviewed by: Dr. Sophie Dix (BSc, PhD)

Dr. Sophie Dix is Head of Medical Affairs at MedExpress. A behavioural neuroscientist by training, Sophie has spent 30 years working at the intersection of medical research, pharmacology, technology and patient communication across the pharmaceutical industry, health technology and charity sectors. At MedExpress, Sophie's role is to ensure that everything the organisation does is grounded in the most current science. That means translating complex clinical evidence into accessible health information across the website, clinical pathways and media communications. It also means working with external press and broadcast media as a named expert commentator, making the science behind weight management and GLP-1 treatments understandable to a general audience. A core part of Sophie's work is building MedExpress's Real-World Evidence (RWE) programme: learning systematically from patient outcomes to understand what works in practice, not just in clinical trials. This patient-level insight feeds directly into improving patient experience and health outcomes. Sophie believes that patients make better decisions when they have access to accurate, evidence-based information. As an advocate for meaningful change in how obesity is understood, Sophie works to reduce stigma and raise awareness of the condition as an illness. This includes reframing the conversation around GLP-1s from aesthetics to public health, while highlighting the health benefits of weight loss and weight management.

Note from the experts

Remember: This blog shouldn’t be regarded as medical advice, diagnosis, or treatment. We make sure everything we publish is fact checked by clinical experts and regularly reviewed, but it may not always reflect the most recent health guidelines. Always speak to your doctor about any health concerns you have.