The doses of sildenafil are 25mg, 50mg or 100mg. Whichever one you choose, you take 1 tablet a maximum of once per day to help you get an erection. Sildenafil is a commonly used medication and has been used to treat erectile dysfunction (ED) for many years.
You can change the dose of sildenafil depending on your response to the medication. As there are different doses, you can find the one that works best for you. You may be prescribed a lower or higher dose if you have side effects or are not getting any benefit from the medication.
You can also switch to another ED medication that works similarly to sildenafil.
How to take sildenafil
When you want to take sildenafil:
- take 1 sildenafil tablet about 1 hour before sexual activity
- swallow the pill whole with some water
- you can expect sildenafil to work within 30 minutes to an hour
- you need to be sexually excited for sildenafil to work
Bear in mind that you can only take 1 sildenafil tablet per 24 hour period.
Eating and drinking with sildenafil
You can take sildenafil with or without food. It's best taken with an empty stomach. Eating fatty foods or heavy meals before taking sildenafil lowers its absorption, so it may take longer to work.
Avoid drinking a lot of alcohol on the days you wish to use sildenafil. This is because alcohol makes it difficult to have erections.
Grapefruit and grapefruit juice interfere with how sildenafil works, so do not have them at the same time as your tablet.
When you take sildenafil, you might get side effects like:
- feeling sick
- hot flushes
Side effects, if any, are usually mild and tend to ease with time. If you have any concerns, speak to a doctor. They may be able to recommend a different dose or suggest you try another erectile dysfunction medication.
What doses of sildenafil are available?
Sildenafil is available in 25mg, 50mg and 100mg dose pills. You’ll likely start off with 50mg. The dose can then be changed if needed to suit you. Take sildenafil as instructed by your doctor or pharmacist for the best results. Below we describe each of the doses of sildenafil.
The usual starting dose for sildenafil is 50mg, taken an hour before you plan to have sex. Before you start taking sildenafil, your doctor will discuss your general wellbeing to prescribe the right dose for you.
If you start taking 50mg tablets and find that you’re unable to get an erection that lasts long enough for sex, you might need to increase your dose. If you have persistent side effects, such as feeling dizzy, you may need to lower your dose.
In either situation, speak to your doctor for advice on what to do. You should not change your own dose of sildenafil unless your doctor has instructed you to do so.
100mg is a higher dose of sildenafil and your doctor may recommend it if the 50mg dose has little effect. If you find the 100mg does not work for you, try the following:
- make sure you’ve taken at least 8 separate doses to give it enough of a chance to work
- switch to another erectile dysfunction medication
- use a non medication option
25mg is the lowest dose of sildenafil available and might be right for you if the 50 mg dose is causing side effects, or if you have certain medical conditions. If 25mg sildenafil is not effective, you may want to consider a smaller daily dose of a different erectile dysfunction medication, such as Cialis daily.
How to choose the right strength of sildenafil
To choose the right strength of sildenafil for you, a doctor may need to talk to you about your:
- current health
- blood pressure
- cholesterol levels
- level of fitness
- history of medical conditions, such as heart problems or diabetes
- previous erectile dysfunction treatments you’ve tried
Once you find a treatment suitable for you, take it as directed by your doctor for best results. You may want to follow the lifestyle tips below to get the most from your treatment.
How to get the most out of sildenafil
To get the most out of sildenafil:
- take the medicine as directed by your doctor or pharmacist
- you need to be aroused for the medicine to work
- avoid fatty foods or heavy meals before taking sildenafil
- avoid drinking too much alcohol when you take the medicine
There may be other factors affecting your sexual performance including:
- emotional factors
- lack of sleep
Speak to your doctor if you notice anything different about your health, start any new medications, or you want an alternative. They will be able to work with you to find the best medicine suited to you.
Do other erectile dysfunction medications have a higher dosage?
Different erectile dysfunction medications have an effect at different doses to each other. A higher dose of one medication does not mean it’s better or will work faster than another medication. Also, some medications may work better for some people than others. What works for you will be unique for you.
Alternative medications for erectile dysfunction include:
- Spedra - tends to work in 15 minutes and lasts 4 hours (available from £29.00)
- Levitra - tends to work in just over 30 minutes and lasts up to 12 hours (available from £40.00)
- Cialis - tends to work in 15 to 30 minutes and lasts up to 36 hours (available from £39.00)
- Cialis Daily - take once every day for daily sexual activity (available from £70.00)
Another option is to use a cream instead of taking a pill. Vitaros cream contains 3mg per gram of alprostadil and works in 5 to 15 minutes.
Non medication options include:
- vacuum pump - this device uses suction to achieve erections
- therapies - therapies such as CBT can address any emotional factors
- pelvic floor exercises - this improves the ability to maintain erections
We go through these treatments in more detail in our erectile dysfunction treatment guide. You can fill out an online questionnaire with ZAVA and find what could work best for you today.
Dr Babak Ashrafi Clinical Lead for Service Expansion
Babak studied medicine at King’s College London and graduated in 2003, having also gained a bachelor’s degree in Physiology during his time there. He completed his general practice (GP) training in East London, where he worked for a number of years as a partner at a large inner-city GP practice. He completed the Royal College of GPs membership exam in 2007.Meet our doctors
Last reviewed: 16 Feb 2022
Sildenafil (Viagra): medicine for erection problems - NHS [Jan 2019][accessed Dec 2021]
Sildenafil 50 mg film-coated tablets - Patient Information Leaflet (PIL) - (emc) [Sept 2020][accessed Dec 2021]
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