Erectile Dysfunction
Erectile dysfunction is the inability to get and maintain an erection. Erectile dysfunction is a very common condition, particularly in older men. It is estimated that half of all men between the ages of 40 and 70 will have it to some degree. Erectile dysfunction can have a range of causes, both physical and psychological.

Physical causes include:
Narrowing of the blood vessels going to the penis – commonly associated with high blood pressure, high cholesterol or diabetes
Hormonal problems
Surgery or injury
Psychological causes of ED include:
Anxiety
Depression
Relationship problems
Sometimes erectile dysfunction only occurs in certain situations. For example, you may be able to get an erection during masturbation, or you may find that you sometimes wake up with an erection but you are unable to get an erection with your sexual partner. If this is the case, it is likely the underlying cause of erectile dysfunction is psychological (stress related). If you are unable to get an erection under any circumstances, it is likely that the underlying cause is physical. Erectile dysfunction can also be a side-effect of using certain medicines.
Erectile dysfunction is primarily treated by tackling the cause of the problem, whether this is physical or psychological. The narrowing of the arteries (called atherosclerosis) is one of the most common causes of ED. In these cases your GP may suggest lifestyle changes, such as losing weight, to try to reduce your risk of cardiovascular disease. This may help to relieve your symptoms as well as improving your general health.
You may also be given medication to treat atherosclerosis, such as cholesterol-lowering statins and drugs to reduce your blood pressure. A number of treatments have been successful in the treatment of erectile dysfunction. Medication, such as sildenafil (sold as Viagra), can be used to manage it in at least two-thirds of cases. Vacuum pumps that encourage blood to flow to the penis and cause an erection are also successful in 90% of cases. Psychological treatments include cognitive behavioural therapy (CBT) and sex therapy.
*See your GP if you have erectile dysfunction for more than a few weeks.
Source: www.nhs.uk