There is a risk of permanent brain damage in severe cases. A membrane called the tunica albuginea helps trap the blood in the corpora cavernosa, thereby sustaining erection.

Users often experience a feeling of well-being, contentment and detachment from daily worries. The major organs it affects are the liver, kidneys, spleen and reproductive organs. The different types of eczema have very different causes and treatments, making their correct diagnosis important. These include Prozac which is thought to stimulate the growth of brain cells in an area of the brain called the dentate gyrus. Magic mushrooms also have a hallucinogenic effect which is generally milder than that associated with LSD. Heavy use can lead to confusion, aggravate existing mental disorders and sap energy.

Some drugs may produce longer term side effects, such as acne and weight gain. The anorexic must be shown to be incapable of making rational decisions about their condition.

Other forms of depression include Seasonal Affective Disorder which is thought to be associated with the approach of winter and may be linked to lack of sunlight. It also affects one in 12 adults. In a small number of cases, people who have taken Viagra have complained of headaches, flushing and stomach-ache.

Side effects include paranoia, suicidal urges and kidney disorder. Insomnia is very common, as is depression. There is a risk of permanent brain damage in severe cases. The tiny air sacs in the lungs called alveoli, through which oxygen is absorbed into the bloodstream, lose their natural elasticity, meaning spent air is pushed back out into the lungs. Some experts believe bulimia is the result of an imbalance of chemicals to the brain, but others think the illness is more likely to be linked to a lack of self-worth. When unconscious, the user is at risk of choking on their own vomit. People with type 1 diabetes can live happy, healthy lives provided they follow a diabetes treatment plan. For example, some people severely restrict the range of food they eat or several children have a psychological fear of food.

Anorexia nervosa is a form of intentional self-starvation. Eczema can appear anywhere on the body but is often found in the skin creases of the elbows and wrists and behind the knees. But if the ovaries are left in place then the chance of recurrence is increased with some women needing a further operation to remove the ovaries at a later date.

The most common are headache, stiffness, confusion and temporary memory loss on awaking from the treatment - some of these can be reduced by placing electrodes only on one side of the head. The disease was transmitted from African green monkeys brought to Germany for animal experimentation.

Foot exercises while sitting down - rotating the ankles and wiggling the toes - prevents the blood pooling in the feet and then struggling to climb up through the veins.