PSORIASIS is a chronic, non-contagious disorder which affects the skin and joints, characterized by flaking, redness and inflammation of the skin. Once thought to be a skin disorder, psoriasis is now understood to be a condition originating in the immune system.

The scaly patches caused by psoriasis, called psoriatic plaques, are areas of inflammation and excessive skin production. Skin rapidly accumulates at these sites and takes on a silvery-white appearance. Plaques frequently occur on the skin of the elbows and knees, but can affect any area including the scalp and genitals. In contrast to eczema, psoriasis is more likely to be found on the extensor aspect of the joint.

The disorder is a chronic recurring condition which varies in severity from minor localized patches to complete body coverage. Fingernails and toenails are frequently affected (psoriatic nail dystrophy) - and can be seen as an isolated finding. Psoriasis can also cause inflammation of the joints, which is known as psoriatic arthritis. Ten to fifteen percent of people with psoriasis have psoriatic arthritis.

The cause of psoriasis starts with the immune system. T cells, a type of white blood cell, usually protect the body against infection and disease by attacking bacteria and viruses. However, when you have psoriasis, your T cells mistakenly attack your skin cells instead. Your body then produces other immune system responses, leading to swelling and rapid production of skin cells. Psoriasis tends to run in families and it usually appears between the ages of 10 and 45.

Psoriasis is an inherited disease. However there are certain triggering factors such as injury to the skin, vaccinations and certain medications that have been responsible for the development of this condition. It usually takes about a month for new cells to move from the lower layers of the skin to the surface. In psoriasis, this process takes only a few days, resulting in a build up of dead skin cells and formation of thick scales.

Psoriasis occurs more likely in dry skin than oily or well-moisturized skin. Excessive alcohol consumption, obesity, lack of or overexposure to sunlight, stress, cold climate, physical illness, streptococcal or HIV infection, superficial wounds, or taking certain drugs such as lithium, beta-blockers such as propranolol, anti-malarial medications and in general poor health results in flaring up of psoriasis.

The symptoms of psoriasis can manifest in a variety of forms. Different types of psoriasis exhibit different characteristics that may change over time. One form may change to another, or several forms may exist at the same time.

• Plaque psoriasis: This is the most common type of psoriasis. It is characterized by raised, red lesions covered with silvery white scales. The scales are caused by a building up of dead skin cells. It may appear on the knees, elbows, scalp, trunk or any other skin surface.
• Guttate psoriasis: It is characterised by numerous small red dots of psoriasis. The lesions may have some scaling. These numerous spots of psoriasis appear over large areas of the body, such as the trunk, limbs, and scalp. It may appear suddenly following a bacterial or viral infection or the administration of drugs like ketoconazole and salicylic acid.
• Inverse psoriasis: This is usually found in the folds of the skin in the armpits, groin, under an overweight stomach or under the breasts. It appears as smooth, red lesions without scaling and may cause irritation due to rubbing and sweating.
• Pustular psoriasis: It is characterized by blisters filled with pus on the skin. The blisters are not infectious. It may be found on the hands and feet or may be spread all over. The skin under and surrounding pustules is red and tender.
• Psoriatic arthritis: About 10% of the patients with psoriasis may develop a form of arthritis called psoriatic arthritis. This may cause redness and swelling, primarily on the hands, feet, knees, hips, elbows and spine. It may cause stiffness, pain and joint damage.
• Nail psoriasis: produces a variety of changes in the appearance of finger and toe nails. These changes include discolouring under the nail plate, pitting of the nails, lines going across the nails, thickening of the skin under the nail, and the loosening and crumbling of the nail.
• Erythrodermic psoriasis: involves the widespread inflammation and exfoliation of the skin over most of the body surface. It may be accompanied by severe itching, swelling and pain. It is often the result of an exacerbation of unstable plaque psoriasis, particularly following the abrupt withdrawal of systemic treatment. This form of psoriasis can be fatal, as the extreme inflammation and exfoliation disrupt the body's ability to regulate temperature and for the skin to perform barrier functions.

Diagnosis of psoriasis is usually based on the appearance of the skin. There are no special blood tests or diagnostic procedures for psoriasis. Sometimes a skin biopsy, or scraping, may be needed to rule out other disorders and to confirm the diagnosis.

As per Ayurveda, Psoriasis is caused by vitiation of vata and kapha dosha. The vitiated doshas affect the skin and blood tissues. They also influence water element of the affected region on skin. Thus the skin which is influenced by affected doshas becomes discolored (white or copper colored), scaly and thin.