Learn how Sildenafil can help treat erectile dysfunction

What is Sildenafil?

Sildenafil is an erectile dysfunction (ED) treatment which can be taken to help men aged 18 and over who struggle to get and maintain an erection hard enough for sex. Sildenafil tablets can make it easier for men with ED to get an erection when sexually stimulated around half an hour to an hour after being taken. 

How does Sildenafil work?

Sildenafil tablets contain the active ingredient sildenafil citrate, which works by relaxing blood vessels and increasing the blood flow to the penis. This makes it easier for men with erectile dysfunction to get and maintain an erection hard enough for sex. Although Sildenafil tablets will help you get an erection, they aren’t aphrodisiacs and won’t work unless you’re sexually aroused.

Sildenafil can be effective for up to four hours after you’ve taken the tablet, so you should find it easier to get an erection when sexually stimulated within this period of time. Once you’ve had sex, the erection should go away. 

There are three different strength tablets of Sildenafil: 25mg, 50mg and 100mg. Sildenafil’s effects will last the same amount of time regardless of which strength of tablet you’ve taken. For more information about the different strengths of Sildenafil, visit our Sildenafil dosages article.   

Who is Sildenafil suitable for?

Sildenafil tablets are intended for use by men, aged 18 and over, with erectile dysfunction.

You shouldn’t take Sildenafil if you: 

• Are currently taking nitrates for chest pain
• Have a heart or liver problem
• Have recently had a stroke or a heart attack
• Have previously had an allergic reaction to Viagra or Sildenafil tablets

The patient information leaflet gives the full list of who Sildenafil isn't suitable for.

How do I access Sildenafil? 

Sildenafil is one of a number of oral medicines to help treat ED symptoms which can be accessed through the Boots Online Doctor – Erectile Dysfunction service.*

Remember, although ED is a common condition, it can also sometimes be caused by underlying health problems or conditions. So if you have erection problems, it’s important that you always speak to your GP to discuss your symptoms so they can make sure this isn’t the case.  

Is there a branded version of Sildenafil? 

The branded version of Sildenafil is perhaps one of the world’s most well-known ED drugs: Viagra. 

Viagra contains sildenafil citrate, the active ingredient in generic Sildenafil. This means that Sildenafil works in a similar way as Pfizer’s branded Viagra, and also has similar side effects. 

How do I take Sildenafil tablets?

You should take your tablet whole with a glass of water, with or without food. If you take the tablet after a large meal, the effects may be delayed somewhat, so if you want the effects to kick in as soon as possible, take the tablet on an empty stomach. No matter what strength, never take more than one tablet a day. 

It’s also worth noting that eating grapefruit or drinking grapefruit juice can also have an effect on how the medicine works, so avoid grapefruit or grapefruit juice when taking Sildenafil.

The amount of time it takes for the sildenafil citrate in the tablets to work is normally between half an hour and an hour. Because of this, you should take Sildenafil tablets at least half an hour before you plan to have sex. 

Remember, you should only ever take Sildenafil tablets if they’ve been prescribed to you by a healthcare professional. It’s really important that you’re honest when answering the questions about your general health and symptoms during the online consultation, as these questions are designed so our online clinicians can assess the treatment’s suitability for you. 

What are the possible side effects of taking Sildenafil tablets? 

Before taking the tablet itself you should be aware of the Sildenafil side effects that you may get after taking the medicine. Some side effects of Sildenafil can affect some people more than others.

Sildenafil side effects are usually mild to moderate and of a short duration. The most common side effects, which may affect up to one in 10 people, include: 

• Headaches

• Stuffy nose
• Dizziness
• Blurred vision or visual disturbances including colour tinges
• Nausea
• Facial flushing
• Hot flushes (symptoms include a sudden feeling of heat in your upper body)
• Indigestion 

You can view a full list of Sildenafil side effects, including uncommon and rare ones, by looking at the patient information leaflet.

What if Sildenafil doesn’t work for me? 

If Sildenafil doesn’t work the first time you try it, don’t worry, as this doesn’t mean it won’t work during future attempts. 

If you’ve used Sildenafil eight separate times without success, then you may want to try a higher Sildenafil strength (if suitable for you) or consider a different oral ED treatment altogether.

The Boots Online Doctor – Erectile Dysfunction service* offers other oral ED treatments, including Spedra and Cialis.

If you don’t want to take oral tablets, you can still consider other treatment methods to help treat ED.

*Treatments provided by Boots Online Doctor are subject to an online consultation with a clinician to assess suitability. Charges and eligibility criteria apply.