Information on Sildenafil

What kind of medicine is sildenafil?

Sildenafil helps men who have trouble getting or keeping an erection, a condition known as erectile dysfunction. It is part of a group of medicines called PDE-5 (Phosphodiesterase type 5) inhibitors. The other medicines in this class are Viagra, Cialis and Levitra. Sildenafil citrate is the active ingredient in Viagra. So both Viagra and sildenafil act in the same way.

How does it work?

Sildenafil and other erectile dysfunction medicines can help by increasing the blood flow into the erectile tissue of the penis when you are aroused. Sildenafil isn’t an aphrodisiac; it will only work once you become sexually aroused. The medicine itself won’t create any sense of arousal or increase your sex drive.

How do I take it?

Sildenafil should be taken at least an hour before sex on an empty stomach. You should not drink more than one or two units of alcohol as this will make sildenafil less effective. It can be dangerous to take more than one sildenafil tablet at a time - in fact you should not take more than one tablet in 24 hours. Sildenafil should not be taken within 24 hours of taking Viagra, Cialis or Levitra.

How quickly does sildenafil work?

Sildenafil usually becomes effective in just under an hour when you take it on an empty stomach. The medicine can remain effective for around four to five hours. This doesn’t mean your erection will last that long – just that you will find it easier to get an erection during that time. Sildenafil may take more than an hour to become effective if you take it after a meal that has a high-fat content.

How effective is it?

How you respond to sildenafil depends on what’s causing your erectile dysfunction, the severity of any underlying cause and your degree of sexual stimulation. If sildenafil does not improve your erection the first time you take it, please don’t give up. The reason it didn’t work may have been that you were not fully aroused. Patients are normally advised to try sildenafil at least eight times before switching to a higher dosage or trying a different medicine.

Are there any side effects?

Like all medicines, sildenafil can have side effects. Thankfully sildenafil's side effects are generally mild and brief. The more common side effects are:

  • Headaches 
  • Light headedness 
  • Facial flushing

Rare side effects from sildenafil include:

  • A stuffy nose 
  • A blue tint to the vision 

If you experience any side effect from taking this medicine please contact us via your Patient Record. If you experience any chest pain when using sildenafil or your erection lasts for longer than five hours, contact the emergency services straight away.

What if I am taking other medicines?

If you think that sildenafil could help you, it is important that you tell us about any other medicines you are taking. Some medicines aren’t safe to take with sildenafil, so it’s important that you are completely honest with us. Useful things to remember:

Nitrates - Sildenafil can’t be taken if you are already taking nitrates. Nitrates are used in some medicines to treat angina and recreational drugs such as ‘Poppers’, ‘Aromas’ or ‘Room Odorisors’. Combining nitrates with sildenafil can make your blood pressure drop dangerously low.

Alpha blockers - If you are taking alpha-blockers such as alfuzosin, doxazosin, tamsulosin or terazosin you should make sure there’s at least a six hour gap between taking the alpha-blocker and taking sildenafil.

Please let us know through your Patient Record if you start taking any new medicines.

Does sildenafil treat the underlying causes of impotence?

Sildenafil will not resolve any underlying physical cause of your erectile dysfunction. As erectile dysfunction is often a symptom of other underlying conditions it is important that you look at the previous messages we have sent. You should be able to see which follow-up tests are recommended in your case. If the cause of your impotence is primarily psychological, sildenafil may help to break the cycle of anxiety and failure associated with being unable to achieve a satisfactory erection. Taking treatment just once gives many men the confidence to carry on without needing to take the medicine again.