Also known as plaque psoriasis, it is defined as a common inflammatory skin condition characterized by frequent episodes of redness, itching, and thick, dry, silvery scales in discrete patches on the skin. It is most commonly seen on the trunk, elbows, knees, scalp, skin folds, or fingernails, but it may affect any or all parts of the skin. When the patches are on the scalp and in body fold areas, the skin is often itchy, but many people with psoriasis do not feel itchy at all. The main problems caused by these patches are by shedding scales and by showing on the skin where they can be seen. Fortunately, psoriasis is unlikely to affect the face, and usually occurs on areas covered by clothes.

Most people with psoriasis find it a burden and a nuisance, but they are not stopped from enjoying life and doing their usual work. However, the condition may involve an important area of the body such as the hands - and this does affect the person's life, and their ability to work with their hands. The cost of caring for psoriasis can be considerable.

What causes Psoriasis?
It appears suddenly or gradually. Age is not a factor, but it commonly starts between 15 to 35 years old. It is characterized by frequent episodes of recurrences and remissions. It may be aggravated by injury or irritation (cuts, burns, rash, insect bites), and it may be severe in immunosuppressed people (such as with chemotherapy for cancer, or with AIDS) or those who have autoimmune disorders such as rheumatoid arthritis.

It is known that the skin in psoriasis patches is growing much quicker than normal skin. In all of us, the epidermis (the outer layer of the skin) grows continuously from its outer surface, and a new layer is reformed each month. In psoriasis, the skin reforms a complete layer each 3-4 days - so that extra skin must shed in scales. This process is similar to healing of the epidermis after an injury - except that normal skin 'knows when to slow down and psoriasis skin does not'. However the actual chemical cause of psoriasis is not known. There have been many scientific experiments performed looking for the cause, but so far changes found seem to result from the rapid growth, and not to cause it.

Sometimes (but not certainly always) psoriasis can run in families, and so it is likely that there are inherited properties causing a "tendency" to the condition. If a person has this tendency, an accident or sudden/severe nervous shock, or some germ infections, can set off the condition and make it appear on the skin.

Medications, viral or bacterial infections, poor digestion, excessive alcohol consumption, obesity, lack of sunlight, overexposure to sunlight (sunburn), stress, general poor health, cold climate, and frequent friction on the skin are associated with flare-ups of psoriasis.

Psoriasis is not infectious in any way. It does not spread on the person who has it by infecting other areas, and it cannot be transferred to other people by any form of contact. Of course this does not stop people worrying about psoriasis if they see it, and fearing that it may infect them.

How severe is it?
The extent and activity of psoriasis varies greatly just as with any other disease. Many people have patches on the scalp or elsewhere, but are not bothered by it and lead normal lives. Others have wider areas of skin involved. Studies in European communities show that about 2% of people are affected. Psoriasis does not cause cancer or affect the blood or the circulation.

Diagnosis
The appearance of the skin rash is enough for a trained doctor to make the diagnosis of psoriasis, without any tests. If there is any problem of general health, blood tests can be performed or X-rays can be taken, but these do not help the diagnosis of the condition itself. A piece of skin can be cut out (biopsy) and sent for pathology testing to be quite sure of the diagnosis.

Treatment
On occasion, especially after a rapid onset, which sometimes occurs in young people, it can settle or disappear. If their skin tans well, people can be free from psoriasis every summer, even though it comes back again in winter.

There are many different conventional treatments, and the correct treatment depends on the activity and extent of the psoriasis, whether the person has fair or dark skin, and whether there are any other exacerbating problems present as well. Minimize flare-ups by avoiding any known aggravating factors.

A list of alternative considerations and treatments should include:
Improving digestive function, improving liver function, improving bowel ecology, alcohol avoidance, fish oil and omega 3 supplementation, fasting, vegetarianism, food allergy elimination diets, sunshine exposure and vitamin D use, a high fiber diet, and stress reduction.