Psoriasis Dr Rob Hicks Psoriasis is a common skin condition which is impossible to prevent.

In this article

What is psoriasis? Symptoms

Causes and risk factors Treatment and recovery

Advice and support

Psoriasis occurs when the skin cells replace themselves too quickly. It usually takes up to 28 days for newly formed skin cells to rise to the surface of the skin and separate from healthy tissue, but in psoriasis it takes just two to six days. There are many different types, but the most common is chronic plaque psoriasis.

Psoriasis usually appears as red, scaly, crusty patches that reveal fine silvery scales when scraped or scratched. These patches may itch and feel uncomfortable. Psoriasis is most common on the knees, elbows and scalp, but can appear anywhere on the body. In some forms the nails or joints are affected.

The condition is chronic, lasting for many years. Most people have periods when symptoms are minimal or the skin is normal but then it flares up again. The impact on a person varies – for some it is no more than a mild irritation while others with psoriasis become withdrawn and don't socialise or form relationships because of the way people react to the appearance of their skin.

The reason psoriasis occurs is unknown, so it's impossible to prevent. However, it seems that the immune system plays a part in the disease. A type of immune system cell known as a T lymphocyte attacks healthy skin cells and triggers further immune responses which stimulate the production of new skin cells.

Many things are thought to trigger the condition, including a skin injury, sore throat or chest infections, certain drug treatments, sunburn and stress.

Psoriasis often runs in families (but can skip a generation) and several genes have been linked to the condition.

It’s important to point out that it isn't contagious or caused by poor hygiene

It’s important to point out that it isn't contagious or caused by poor hygiene.

About two per cent of the UK population have psoriasis, and men and women are equally affected.

The condition can occur at any age, but it mostly occurs between the ages of ten and 40, often during puberty. It affects up to one in 50 children, but it's rarely seen in children under two years old.

A type called guttate psoriasis is common in children and often follows an upper respiratory infection. It produces small, raindrop-like patches across the upper trunk and limbs that last a few months.

Children suffering from psoriasis appear to have lost control of cell turnover, with skin cells reproducing faster than old ones are shed. This leads to layers of skin piling up, with the old silvery scales of dead cells on the surface forming the characteristic patches.

First-line treatments include emollients (oily preparations that prevent water loss, moisturising the skin), skin softeners and topical drug therapy applied to the skin, such as vitamin D derivatives, tar preparations, steroids, dithranol preparations and vitamin A derivatives.

Ultraviolet B light therapy, systemic medication (methotrexate, ciclosporin, aitretin, hydroxycarbamide), and biologics designed to block specific molecules in the immune system that trigger development of psoriasis (etanercept, infliximab, efalizumab) may be used under specialist hospital supervision.

The treatment recommended will depend on the type, severity and location of the psoriasis.

The Psoriasis Association

Tel: 0845 676 0076
Email: mail@psoriasis-association.org.uk
Website: www.psoriasis-association.org.uk

Psoriasis and Psoriatic Arthritis Alliance

Email: info@papaa.org
Website: www.papaa.org

Psoriasis Scotland

Website: www.psoriasisscotland.org.uk

This article was last medically reviewed by Dr Trisha Macnair in July 2009.