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.
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.
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 furring-up 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.
Psychological problems can also influence the ability to get and maintain erections. 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.
The side effects of medicines such as some treatments for high blood pressure and depression can cause ED. Medicines can also affect sexual edrive 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.