Sildenafil and erectile dysfunction: the facts about treatment

What can be done for impotence?


What is Sildenafil?

Sildenafil is the active ingredient which is found in Viagra. It is used to treat erectile dysfunction which can be defined as the inability to achieve or maintain an erection long enough to have successful sexual intercourse.

It works by preventing the action of an enzyme found in the body known as phosphodiesterase 5 (PDE-5); it is known as a PDE-5 inhibitor. Blocking the action of PDE-5 allows the blood vessels of the penis to relax and so widen which in turn encourages the flow of blood into the penis when sexually stimulated. This, in turn, helps to create and maintain an erection.

Sildenafil can take between 30 and 60 minutes to work but you can take it up to four hours before you want to have sexual intercourse. However, in order for it to work, you will need to be sexually aroused.


Order effective treatment for erectile dysfunction discretely

Product Img
Sildenafil from £7.00
Product Img
Levitra from £23.45
Product Img
Spedra from £20.99
Product Img
Vardenafil from £23.45
View all treatments

Can I take Sildenafil?

Sildenafil is not suitable for treating women or children but is designed to treat erectile dysfunction in men over 18 years old. If it is given for pulmonary hypertension then it may be given to women and children over one year.

Sildenafil however is not suitable for everyone and should not be taken if you:

  • Suffer from heart disease
  • Suffer from liver disease
  • Take medication known as nitrates for angina
  • Have low blood pressure
  • Have had a stroke
  • Have an inherited eye disease such as retinitis pigmentosa
  • Have had an allergic reaction to any of the group of PDE-5 inhibitors (drugs for erectile dysfunction)

There are other conditions that may mean that Sildenafil will not be suitable for you and you will need to consult your doctor if you suffer from any of the following:

  • Sickle cell anaemia
  • Have leukaemia
  • Have cancer of the bone marrow (multiple myeloma)
  • Have a stomach ulcer or other ‘bleeding’ condition such as haemophilia
  • Have a deformity of the penis or a condition known as Peyronie’s disease

How to take Sildenafil?

Your doctor or pharmacist will advise you on the best way to take the medication. The tablets come in 25 mg, 50 mg and 100mg strengths and the usual initial dosage that is recommended is 50 mg to be taken no more than once per day; the dose can then be increased or decreased as needed. It is best if taken on an empty stomach as it will take longer to work if there is food in your stomach.

Sildenafil is available as a liquid and the dosing directions will be given on the label.

How effective is Sildenafil when used to treat erectile dysfunction?

Sildenafil is very effective in treating erectile dysfunction and approximately two-thirds of men report having harder erections as a result of using it.

If it does not work for you, this may be for a number of reasons including:

  • You have not waited long enough for it to work before attempting to have sexual intercourse
  • You have waited too long after taking it to have sex and the effects have worn off
  • The dose was too low for you. Speak to your doctor or pharmacist and they will be able to advise you
  • You are not sufficiently sexually aroused

Sildenafil does not work for me, are there any other medications I can try?

If you have ruled out any of the reasons given above as to why Sildenafil has not worked for you, there are other versions of PDE-5 inhibitors (phosphodiesterase 5 inhibitors) which you can try. They are:

Another drug called Alprostadil is available as an injection treatment, which is where you inject alprostadil into the base of your penis. It is available as a urethral application, which is where you place a small pellet containing alprostadil into your urethra (the tube which your urine passes through and which opens at the end of your penis). It is also available as a cream that is applied to the opening of the urethra on the tip of the penis. You will be taught how to use the preparation you have been prescribed.

There is also an alprostadil cream available which is branded as Vitaros. It is applied using a dropper placing the creams on the head of the penis where it is absorbed through the skin. It is applied 5 - 30 minutes prior to sexual intercourse and is effective for one to two hours

Alprostadil is available on prescription but it is only prescribed on the NHS under certain circumstances

Can Sildenafil be used over a long period of time?

Sildenafil has been licenced for use in the UK since 1998 and studies carried out in the years since have not found any harmful or lasting side effects occurring as a result of using it.

Where can I get Sildenafil?

  • Sildenafil is available on the NHS if you suffer from pulmonary hypertension or erectile dysfunction. Sildenafil which is sold as Viagra is not available on the NHS.
  • Sildenafil is also available on a private prescription but the full cost of the drug must be paid in these circumstances.
  • It is possible to buy Sildenafil over the counter but this must be done with the supervision of a pharmacist. They will enquire about your general health and if they feel it is necessary they will refer you to your doctor if they are concerned that giving Sildenafil is not appropriate in your particular case.
  • It is also possible to buy Sildenafil on the internet. If you decide to do this it is vital that you only use pharmacies that are registered with the General Pharmaceutical Council. There are many bogus sites that do not sell genuine medication.

What are the side effects?

There are a number of common side effects which are associated with Sildenafil. These include:

  • Nausea
  • Headaches
  • Flushing
  • Indigestion Stuffy nose
  • The vision that is blurred or tinged with colour

There are also a number of serious side effects. They include:

  • Sudden decrease or total loss of vision
  • Erections which may be prolonged (lasting more than four hours) and painful
  • A serious skin reaction may include swelling, blistering, peeling and fever. There may also be blistering of the genitals and around the mouth and eyes
  • Chest pain
  • Seizures
  • On rare occasions, the allergic reaction may be so strong that it results in a person going into anaphylactic shock. If you experience any of the following it may be necessary to call 999 or go straight to A&E
  • The skin reaction is very severe
  • You are tight chested and wheezing
  • You are struggling to breathe or talk
  • Your mouth, face, lips or throat begin to swell

Can I take Sildenafil with other types of medication?

It is important that you tell your doctor or pharmacist about any medication you are taking including herbal remedies and vitamin supplements. Some medications are definitely not to be taken alongside Sildenafil:

Do not take Sildenafil if you are taking or have recently taken riociguat (Adempas) or nitrates (medications for chest pain) such as isosorbide dinitrate (Isordil), isosorbide mononitrate (Monoket), and nitroglycerin (Minitran, Nitro-Dur, Nitromist, Nitrostat, others).


Sildenafil was first seen when Viagra was launched in 1998. It was hailed as ‘the wonder drug’ and it brought the common but secret condition of erectile dysfunction into the limelight.

Before Viagra, couples suffered in silence in sexless marriages believing that this was their lot. Many marriages did not survive as the lack of intimacy drove a wedge between couples. Partners were feeling rejected and sought solace elsewhere.

Whilst no form of medication is perfect, Viagra has brought the spice back into the lives of many couples and for this, there are many people who are truly grateful.

Buy Viagra, Cialis or Spedra or their generic versions from Dr Felix, your trusted online pharmacy


We’re a fully regulated UK pharmacy, with qualified
British doctors and happy customers.

Orders not approved will be fully refunded

Your trusted online doctor

Order now for delivery on Wednesday