Erectile dysfunction (ED) or impotence, occurs when a man has difficulty with either getting or keeping an erection long enough for satisfactory sexual activity.

It is one of the commonest sexual problems in men, affecting about half of all men over 40 at some point. It becomes more common and severe as men get older.


Causes and Risk Factors

There are a number of causes of ED. In around two thirds of cases, there are physical problems affecting the blood and nerve supply to the penis.

However, there is a complex relationship between physical and psychological aspects of sexual function. For instance, physical health problems can cause psychological distress that can have an additional effect on erection problems.


In younger men who consult the doctor, the initial problem is often anxiety over the reliability of an erection. However, occasional episodes of ED are common and do not mean there will be persistent problems in the future.
As men get older, it is common for them to need greater stimulation. A change in sexual foreplay and technique may be necessary to ensure a good, sustained erection.

Many men feel embarrassed when they first discuss the issue with their doctor or practice nurse. But, particularly since the launch of the drug sildenafil (Viagra), awareness and understanding from health professionals is high and the consultation will almost certainly be less embarrassing than feared.

A full physical examination is undertaken. The doctor will request blood tests to look for medical problems, such as anaemia, diabetes, liver disease, high cholesterol or hormone abnormalities.

More specialized tests to assess blood flow and the way the nerves are working can be done at the hospital.


Anxiety, fear and guilt are common causes of ED. Unsatisfactory sexual and relationship experiences may lie behind these issues.

Stress at work, depression, boredom with current sexual practices, partner conflicts and unresolved issues about sexual orientation may all cause problems.

Several conditions prevent sufficient blood getting into the penis and so cause ED. These include diabetes and vascular disease such as the effects of long-standing high blood pressure and high cholesterol which cause narrowing of the blood vessels. There can also be problems with keeping the blood within the penis (veno-occlusive disease), resulting in erections that are quickly lost. Problems with the nervous system can affect the transmission of signals from the brain to the blood vessels in the penis. This occurs in conditions including multiple sclerosis, spinal cord injury, diabetes and Parkinson’s disease. The nerves involved in sexual arousal can also be damaged in surgery to the pelvic area, such as removal of the prostate. In a number of cases, problems with testosterone and other hormone levels, can also affect erection.

The side effects of medicines such as some treatments for high blood pressure and depression can cause ED. Medicines can also affect sexual drive and desire (libido), or cause problems with ejaculation and orgasm. These can have a knock-on effect on erections.

Drinking too much alcohol commonly affects the ability to get and maintain an erection. In the longer term, it interferes with the production of the male hormone testosterone, which can reduce libido and interfere with erectile performance. Smoking damages the circulation, and increases the risk of erection problems. Similarly, being physically inactive, which contributes to poor cardiovascular fitness, may increase the risk of ED.


A healthier lifestyle can often be beneficial and can help prevent any further deterioration caused by underlying medical conditions. Stopping smoking for those that do is extremely important. A moderate amount of exercise and healthy diet may help. Alcohol intake should be moderated and stress should be identified and managed where possible.

In around 95% of cases, a suitable treatment can be found. The simplest treatments are talking therapies and tablets.

If the cause is mainly worry, other psychological problems or relationship difficulties – such as arguments and disagreements about sex – then talking to a counselor or psychosexual therapist will be most helpful. Therapy includes:

  • Penile prosthesis : surgically placed semi-rigid or inflatable prosthesis within the penile body
  • Penile vascular reconstruction : reserved for specific young patients who have suffered from pelvic trauma involving the penile vasculature

If hormone levels are found to be low, then replacement therapy with testosterone is often very useful.

In most other circumstances, a trial with a medicine that helps men obtain and keep an erection is the next step. There are now three different brands of tablets known as phosphodiesterase type -f (PDE5) inhibitors. The two newer drugs tadalfil (Cialis) and vardenafil (Levitra) work in a similar way to sildenafil (Viagra), the first drug of this type, but take effect more quickly. Men taking nitrate drugs (e.g., glyceryl trinitrate) for angina must not use PDE5 inhibitors at the same time as they can dangerously lower the blood pressure.

For all three medicines, sexual foreplay is needed to start the arousal process. The ability to have erections can last for several hours or with tadalafil for up to about 24 hours.

Side-effects with these treatments tend to be minor and may include headaches, nausea, indigestion and a stuffy nose. However, they are prescription only drugs and are not suitable for everyone. There have been rare but serious complications.

In more severe cases of ED, where patients do not respond to PDE5 inhibitors the need for second line agents should be assessed. These include the following:
  • Intracavernosal injections : local injections of one or a combination of alprostadil, papaverine & phentolamine.
  • Vacuum constriction devices : these are effective in most patients and do not require a prescription