Healthy erections are achieved in one of two ways: as a result of erotic mental stimuli or manual stimulation of the penis. In either case, the penile shaft is manipulated, causing Nitric Oxide to be released and resulting in the relaxation of the arterial muscles of the penis. An adequate level of testosterone and intact pituitary glands are also required for erection; therefore, medical conditions affecting these can result in the inability to achieve or maintain an erection.
There are a number of treatments for the condition, and the appropriate treatment is determined on the basis of the cause of the condition.
Older men with diabetes frequently suffer with damage to the inner walls of the blood vessels, restricting the blood flow and resulting in erectile dysfunction. Where inadequate testosterone levels are causing the impotence, testosterone supplements usually work effectively and permanently.
Perhaps the most common - and certainly the most famous - treatment for the condition is the PDE5 Inhibitor. These drugs, such as Levitra and Viagra, were discovered in the 1990s and work by suppressing the PDE5 and replacing the cGMP with itself. This allows the mechanisms involved in erection to work more effectively and reliably. There are no known, major side-effects to using PDE5 Inhibitors, but the drug only works as a temporary cure.
The vacuum pump is another uncontroversial (and safe) treatment, though it is known to have limited effectiveness. The pump is used to produce an erection of the penis, then a suppression ring is fitted to the base of the penis to ensure the erection is kept throughout intercourse. The suppression ring can only be worn, however, for a maximum of thirty minutes. The majority of the research suggests that the erections developed as a result of the vacuum pump are less firm than those occuring naturally; but there is some evidence to suggest that long-term use of the pump can increase the effectiveness of natural erections.
In cases of mild erectile dysfunction, less reliable drugs - known as 'dopamine receptor agonists' - can be taken, and are known to act upon the D2 receptors.
Injections into the penis are known to be generally extremely effective, but are believed to be risky and can result in priapism. In extreme cases, surgery may also be considered. Rigid or inflatable implants can be fitted; although these are generally effective, they are also irreversible and very expensive. Surgery is usually only considered as a final option.