What is psoriasis?

Psoriasis is a common skin disorder that affects men and women at any age.

It causes a thick, rough, dry build-up of the outer layer of the skin. These red patches on the skin are covered by silvery white scales and mainly develop on the knees, elbows, back or scalp, but almost any area of the body can be affected.

Psoriasis is not infectious and does not scar the skin.

Psoriasis is a chronic disease, which means you may have it for months or years. However early treatment may minimise the severity of the disorder.

What causes psoriasis?

Psoriasis is the growth of too many skin cells — a normal skin cell matures in 28—30 days but a psoriatic skin cell takes only 3—6 days. The exact cause of this is not known. There may be a genetic link that is triggered by another factor — for example, a throat infection, stress or injury to the skin.

There are certain times in life when the tendency to develop psoriasis is increased — for example, during puberty or in women during or after the menopause. However no obvious cause can be detected in the majority of people who develop psoriasis.

Are there different types of psoriasis?

There are different types of psoriasis, but it is important to remember that psoriasis changes over time — it may flare up, improve, change to another form, or several forms may exist at the same time:

How is psoriasis diagnosed?

Your doctor will usually make the diagnosis by examining your skin and/or nails. Blood tests may be ordered if you also have inflamed joints.

How is psoriasis treated?

Although there is no cure for psoriasis, treatment is usually effective. The skin becomes less scaly and may look completely normal. However there is a tendency for psoriasis to return. There are several different treatments available and you should discuss with your doctor which treatments are best suited to you:

What can I do?

Because the cause is not yet known, doctors do not know how to prevent psoriasis. However you may be able to prevent serious outbreaks by treating small plaques when you first see them and it does help to use skin moisturisers instead of soap to prevent the skin from drying.

My psoriasis is very bad and isn’t responding to treatment. Are there any other options?

There are other options for people with severe psoriasis (i.e. at least 20% of their body surface is covered with psoriasis) who do not respond to the treatments listed above. These treatments are effective but are used only under strict supervision and only after the other, simpler treatments have been tried first.

There are side-effects to all of these treatments which your doctor will discuss with you. You must also advise your doctor if you are pregnant, as many of these treatments cannot be used during pregnancy:

What is psoriatic arthropathy?

Psoriatic arthropathy is a form of arthritis that affects about 10—20% of people with psoriasis.

The arthritis affects the lining of joints causing swelling, pain and stiffness.

The arthritis is usually limited to just a few joints and sometimes affects the spine, giving a painfully stiff back or neck. It can also affect other joints such as the knees.

Frequently finger and toe-nails develop pits, discoloration and thickening. The outlook is generally good, as psoriatic arthritis is not usually a crippling disease.

See Psoriasis Clinic

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Reviewed: December 7, 2006