Viagra Dosage: What Dose Is Right For Me?
Medically reviewed by
Dr Zoe MillerLast reviewed: 18 Feb 2025
While Viagra has been improving the sex lives of people with erectile dysfunction (ED) for over 20 years, to get the most out of it, you need to make sure you’re on the correct dose. Being on the right dose not only affects how well Viagra works but can also make side effects less likely.
Your doctor will work with you to make sure you’re on the right Viagra dosage for your needs, and if you still aren’t getting the results you want, they may be able to prescribe a more suitable treatment.
In this guide, we explore the different Viagra doses available and how they can affect you, so you can go forth and make an informed decision on your erectile dysfunction treatment with ease.
What Viagra dosages are available?
Viagra is available in 3 different dosages: 25mg, 50mg, and 100mg. The dose you’re prescribed will depend on your ED symptoms and any other health conditions you have.
The usual starting dose for Viagra is one 50mg tablet. This means it contains 50mg of the active ingredient sildenafil. This dose may not work for everyone, so you may still find it difficult to get or keep an erection long enough for sex.
If this is the case, your doctor can increase your dose to 100mg to see if you get the results you want. If 50mg does work for you, but you get side effects, your doctor may reduce your dose to see if you still get the results you want but with fewer side effects.
Below is an overview of the different strengths of Viagra:
| Strength | Dosage type |
|---|---|
25mg |
Minimum |
50mg |
Standard |
100mg |
Maximum |
Standard dose: 50mg Viagra
50mg is the usual starting dose for Viagra. This will be prescribed if your doctor has checked your medical history to make sure it’s safe for you to take and you do not take any medications that could interact with it. This is considered the best starting dose as it’s usually safe for the person taking it and can be increased or decreased as needed by your doctor to suit your needs.
If you are prescribed a 50mg dose of Viagra, you should aim to take it 1 hour before sex and swallow it whole with a glass of water to get the best results.
This dose has a typical success rate of around 74%, but it may not always work for you right away, so don’t give up if you’re not seeing results.
Never take more than your prescribed dose or more than 1 tablet per day.
Viagra is also available over the counter at 50mg in the form of Viagra Connect. Although 50mg is safe to take for most people, we do recommend speaking with your doctor before trialling Viagra Connect if you have any pre-existing health conditions or are taking any medications. A pharmacist will also make sure it’s safe for you to take before you can buy it.
Maximum dose: 100mg Viagra
100mg is the maximum dose of Viagra that’s safe to take and is usually only prescribed for:
- individuals with severe erectile dysfunction
- patients who have found lower doses to be ineffective and have been told by their doctor to increase their dose
A 100mg Viagra dose has an average success rate of 82%, higher than the 74% average of the 50mg dose. However, due to its strength, it will only be prescribed if 50mg is not working for you after taking it on 8 different occasions.
Taking more than 100mg will not make Viagra work better and will increase your risk of serious side effects. It is not safe to increase your dose without speaking to a doctor. Always follow your doctor's advice and never take more medication than you have been prescribed.
Lowest dose: 25mg Viagra
25mg is the lowest dose of Viagra. If you get side effects that bother you while taking the medication, your doctor may suggest taking a lower dose to see if this lessens side effects while still helping you get and keep an erection.
You may also be started on a low dose of Viagra if you:
- have high blood pressure and take alpha-blockers
- are taking certain medications called protease inhibitors, which you may be taking if you’re getting treatment for HIV
To get the best chances of success with a smaller dose, we recommend taking your tablet on an empty stomach and avoiding alcohol, which can interfere with its effectiveness.
You can request Viagra and highlight your preferred dose for a doctor without leaving the house. Simply complete a short medical questionnaire to get started. Our doctors will make sure your treatment is suitable and safe for you to take. They will also check which dose is best for you and whether your preference is suitable based on your answers. If it is, we’ll send it straight to your home in discreet packaging.
What dose of Viagra should I take?
The dose of Viagra you should take is the dose your doctor prescribes you. This is because the correct dose of Viagra will differ from person to person depending on how severe their erectile dysfunction is. Doses are also altered depending on medical history and whether you’re taking another medication that might interact with Viagra.
You should take Viagra as your doctor has prescribed and raise concerns with them if you think your current dose is not working. You need to be sexually aroused for Viagra to work and sometimes it takes time. Because of this, it’s recommended to try Viagra at least 8 times (no more than 1 prescribed dose in 24 hours) before concluding whether it may or may not be right for you.
Remember that Viagra can help you get and keep an erection, but it does not affect how quickly you ejaculate. You may also need to use premature ejaculation treatment.
What affects how much Viagra you can take?
Weight
While Viagra dosage is not directly adjusted based on weight, heavier individuals with a higher body mass index (BMI) may find the standard dose of 50mg less effective and might require a 100mg prescription under a doctor’s supervision.
On the other hand, individuals with lower body weight may experience more side effects and respond better to the 25mg dose. However, it might be that 50mg is right for you, regardless of your BMI.
Health conditions
Certain health conditions can influence how much Viagra you can safely take:
Liver or kidney problems: Conditions affecting the liver or the kidneys can sometimes affect how Viagra is metabolised, meaning a lower dose (25mg) is often recommended.
Cardiovascular issues: Patients with certain cardiovascular risk factors are unsuitable for Viagra treatment. If you can take Viagra, your doctor may want to monitor you closely during treatment.
Medications: Other medications like protease inhibitors, nitrates, or alpha-blockers can interact with Viagra or affect how much Viagra you can take. Your doctor may recommend a lower dose or suggest an alternative ED treatment in some cases.
“The best Viagra dose for you is tailored to your unique needs. Whether it’s adjusting the dose based on your current medications or other health conditions, the goal is to find the safest and most effective option for you. You should always talk to your doctor to determine the best dose for you and let them know how you respond to the medication, as sometimes dose adjustments are required.” – Dr Zoe Miller, Medical Editor.
Changing your current dose
To change your current dose, you’ll first need to speak to your doctor. You should never change doses without consulting them beforehand.
If you want to change dose because Viagra isn’t working for you, your doctor may recommend trying it a few more times. This is because It can take some time for it to work as it should, especially if you are nervous. If you keep trying and Viagra still doesn’t work, your doctor may recommend changing the dose or an alternative treatment.
If you want to adjust your dose because you’re getting side effects, you should speak to your doctor beforehand, as they may think changing treatment is more suitable than changing dosage.
If Viagra is not working for you, there are alternative treatments available for ED. If you are unsure about which treatment may be right for you, with ZAVA you can try an erectile dysfunction trial pack, which contains 3 different ED treatments.
Which dose of Viagra works best?
Although the success rates of Viagra increase with the strength of the dose*, how much Viagra you need to take for an effective treatment depends on your symptoms. Some people may find that 25mg of Viagra is enough to get and keep an erection, with fewer side effects, while others need 100mg to get results. You may find that the recommended Viagra dosage of 50mg is right for you, but it can take a few tries before any dose works as it should.
*25mg (62% effective), 50mg (74% effective), 100mg (82%)
Which dose of Viagra works the quickest?
Every dose of Viagra will start working in around the same amount of time. Changing your dose does not change how fast the medication starts working.
Sometimes Viagra can work in as little as 30 minutes, but this depends on how sexually aroused you are, how quick your metabolism is, and what you have eaten before or with your dose. But most of the time, Viagra will get to work within an hour, regardless of the dose you’re taking.
➤ For more information, view our guide to how quickly Viagra works and explore tips for getting the best results.
Is there anything that can affect your dose of Viagra?
No matter what Viagra dosage your doctor has recommended, your general health, lifestyle choices and any other medication you’re taking can all affect how well Viagra works.
To make sure you get the most out of Viagra, make sure you are:
- aroused – Viagra won’t work for you if you’re not aroused regardless of the dose you’re taking
- not tired
- managing your stress levels, as it is harder to get aroused and achieve an erection with Viagra
When taking Viagra, you should avoid:
- eating high-fat, greasy, or large meals, as this affects how your body absorbs Viagra, which can weaken or delay the effects
- drinking alcohol before using Viagra, as elevated alcohol levels make it more difficult to get an erection with or without Viagra and can also increase the likelihood of getting side effects
- putting too much pressure on yourself (or a partner), as this can make it harder to get and keep an erection
These factors are more likely to affect how Viagra works for you than the dose you’re taking. So it’s important to make sure you’re doing everything you can to get the most out of your treatment. And if it’s not working initially, it might when you try again.
More than 50% of patients who struggle to get an erection after their first dose of 50mg of Viagra do get their desired results with repeated use. So if it’s not working for you, and you aren’t getting side effects, keep trying.
What happens if you take more than the recommended Viagra dosage?
Taking more than your prescribed dose of Viagra can lead to serious health risks and side effects. The maximum recommended dose of Viagra is 100mg per day, and exceeding this amount can result in dangerous side effects, such as:
- severe headaches
- dizziness or fainting
- blurred vision or temporary vision changes
- priapism (a painful erection lasting more than 4 hours), which requires immediate medical attention to prevent permanent damage
If you accidentally take too much Viagra, contact a doctor or seek medical help immediately. In severe cases, such as chest pain, difficulty breathing, or a prolonged erection, call 999.
Is Viagra the strongest ED medication?
As ED medications contain different active ingredients, the dosage may be different but this does not mean one is stronger than the other. Most erectile dysfunction medications, including Viagra, are tablets that you take when you need them to get an erection and no more than once in 24 hours, except Cialis, which can also be taken as a daily tablet called Cialis Daily.
If you’re considering an alternative treatment to Viagra, you can compare dose strength and efficacy of different ED medications in this table:
Remember that you should always consult a healthcare professional if you want to change your dose or try an alternative treatment for ED.
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Conclusion
The right Viagra dosage for you depends on many factors, including health conditions, and whether you’re taking any medications. If you’re fit and healthy, the standard dose of 50mg is considered safe to try. However, exploring your options with a doctor is the best way to ensure you’re starting on the right dose, which can reduce your risk of side effects and improve its effectiveness.
Don’t worry if Viagra isn’t working for you or if you’re experiencing side effects from the medication, as dosage can be adjusted, and you can also try alternative treatments for ED. When you request Viagra or other ED medication with ZAVA, our online doctors will provide you with the support and advice you need.
Frequently asked questions
What doses is generic Viagra available in?
Generic Viagra, more commonly known as sildenafil, is available in the same doses as Viagra: 25mg, 50mg, and 100mg. Sildenafil and Viagra work in exactly the same way and contain the same ingredients, so if you are prescribed sildenafil, it will be in the same doses as you would be with Viagra.
The only difference between Viagra and sildenafil is the look and shape of the tablet and the name on the tablet pack, they may also have different non-active ingredients. Non-branded treatments like sildenafil are usually a cheaper alternative to branded medications like Viagra, and because of this, are more likely to be prescribed on the NHS.
How many Viagra will a doctor usually prescribe?
The dose for Viagra is 1 tablet as needed, up to once a day. The tablets come in packs of between 4 and 28, and the size of the pack that your doctor prescribes depends on your individual needs.
When you’re first starting treatment, a 4-pack will likely be recommended to see how you respond. However, if you know that Viagra works well for you, a larger quantity of tablets might be more suitable to avoid frequent prescription renewals.
If you’re unsure about how you’ll react to Viagra, you can buy an erectile dysfunction medication trial pack, containing 3 different types of medication.
Which dose of Viagra has the fewest side effects?
The lowest dose of Viagra (25mg) has the fewest side effects. This is because it contains the lowest amount of the active ingredient, sildenafil, reducing the likelihood of symptoms such as headaches, flushing, or dizziness.
If you experience any side effects from your Viagra treatment (of any strength), it’s important to let your doctor know right away.
How many mg of Viagra should I take?
The dose of Viagra you should take depends on your specific needs, age, and medical conditions:
➤ 50mg is the usual starting dose.
➤ 25mg is usually prescribed for men who have health issues or experience side effects with higher doses.
➤ 100mg is the maximum dose, for those who don’t see results with 50mg but don’t experience severe side effects of the medication.
Always follow your doctor’s advice and never exceed your recommended dose.
Is 25mg Viagra strong enough?
The 25mg dose of Viagra is strong enough for some people with erectile dysfunction, especially those who are more sensitive to the medication or prone to side effects. It is often prescribed for those with underlying health conditions or taking certain medications that may interact with higher doses. However, for moderate to severe ED symptoms, 50mg or 100mg may be more effective.
If Viagra 50mg is out of stock, can I take 25mg tablets?
If you are prescribed Viagra 50mg and it is unavailable, you can take two 25mg tablets to achieve the same dose. However, this should only be done after consulting your GP or online doctor to ensure it’s safe and appropriate for you.
Can I take two 50mg of Viagra in one day?
If you are prescribed 50mg of Viagra, you should never take more than one dose in 24 hours, even if it’s 2 x 50mg tablets. Doing so increases the risk of serious side effects like low blood pressure, dizziness, and priapism (a prolonged erection that requires medical attention).
If you are prescribed 100mg of Viagra and this is unavailable, you can take two 50mg tablets to achieve the required dose but you must take these at the same time.
If you have sex more than once a day regularly, or more than 3 times a week, it may be safer and more convenient to use a daily ED treatment like Cialis Daily, which means you’ll always be ready.
Is 100mg of Viagra powerful?
Yes, 100mg is the highest recommended dose of Viagra. It’s typically prescribed when lower doses (25mg or 50mg) haven’t been effective. However, it’s important to use this dose only under the guidance of a doctor, as it increases the risk of side effects. If you’ve been prescribed 100mg, it means your doctor has assessed it as the best option for you.
What happens if you miss a dose of Viagra?
There is no specific ‘missed dose’, unlike most medications you take daily, Viagra is only taken as and when you need it. However, if you forget to take Viagra before you’re planning to have sex, you can still take it as soon as you remember. Keep in mind that Viagra works best when taken 30 minutes to 1 hour before sex.
After completing her first degree, she went on to study graduate-entry medicine at Warwick University. After graduating as a doctor, she worked within the West Midlands in Urology, Respiratory Medicine, Infectious Disease, and Psychiatry before transitioning into a full-time medical communications role.
Meet our doctorsLast reviewed: 18 Feb 2025
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