Medical information for patients


Psoriasis is a common condition affecting the skin. It causes red, scaly patches. In addition it can affect the joints, nails and eyes.


Psoriasis can cause as little as a single dimple on one of your finger or toe nails, or affect as much as the majority of your skin surface, your joints, and your eyes. 2% of people (1 in 50) have psoriasis to some degree.

The most commonly affected areas are the back of the elbows and the front of the knees. It often affects the scalp, and can affect any part of the body. The standard appearance is of red areas where the skin is thickened and crusty, often with silvery flakes which come off easily. This appears as patches, which are known as plaques.

Types of psoriasis

Sometimes parts of the body other than the skin can be affected:

Though the rash is sometimes quite obvious, it is not infectious and cannot be caught by contact.


Psoriasis runs in some families, but that is not to say that everyone in a family will get it. It can start at any stage in life, but most develop their first symptoms between 11 and 45 years old. Often it starts at puberty.

The cause is unknown but, as well as a genetic link, a number of things seem to trigger a first attack:

The skin, in the patches that are affected, replaces itself at a much quicker rate than the rest of the skin normally does. Normal skin replaces itself by pushing up new skin cells from below over a period of 28 days, but in psoriasis this takes as little as 4 days.

As with all diseases, and problems of the skin in particular, stress can aggravate psoriasis.


Usually your doctor will make the diagnosis from the appearance of the rash. If you have inflamed joints your doctor may want to arrange some blood tests. Rarely, in cases of doubt, a sample of flakes scraped from the skin, or a small sample of skin (a biopsy), will be sent to the laboratory.


There is no "cure" for psoriasis, but many people have long periods when it does not trouble them. Sometimes it gets better on its own, but most people need some treatment.

Treatments include:


No prevention is known. If you have psoriasis it does help to use skin moisturisers to prevent the skin drying. If you are washing or taking a bath or shower use one of the moisturisers instead of soap.

Further information


Psoriasis: A patient's guide, by Dr Nicholas Lowe
A comprehensive single volume source of information on psoriasis for patients and the general public.
The Psoriasis Handbook, by Mariel MacFarlane
A self help guide to psoriasis.
Understanding Skin Problems, by Linda Papadopoulous, Carl Walker
Acne, Eczema, Psoriasis and related conditions. Also available as an Adobe eBook download from
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