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What is psoriasis?

Psoriasis is a skin condition that results in patches of skin with silvery scales, and red and flaky areas that can be itchy, sore, or sometimes painful.

The most common areas affected are the scalp, elbows, knees, and lower back, although any skin surface may be involved. It can also occur in the nails and body folds.

Psoriasis is not contagious and cannot be passed from person to person, but it can occur in members of the same family.

Psoriasis usually begins in early adulthood or later in life. In most people, the rash is limited to a few patches of skin. In severe cases it can cover large areas of the body. The rash can heal and come back again throughout a person's life.

What does psoriasis look like?

Different types of psoriasis cause different symptoms. The most common type, plaque psoriasis, causes thick red plaques covered with silvery scales.

Psoriasis image © Interactive Medical Media, LLC

Symptoms of psoriasis

Psoriasis starts as small red bumps, which enlarge and become scaly. The skin appears thick, but bleeds easily if the scales are picked or rubbed off.

In addition, the rash may produce:

  • Itching
  • Pitted, cracked, crumbly or loose nails

The signs of psoriasis vary depending on the type you have. Some common signs for plaque psoriasis - the most common variety of the condition - include:

  • Plaques of red, inflamed skin, often covered with loose, silver-coloured scales. These plaques may be itchy and painful and sometimes crack and bleed. In severe cases, the plaques of irritated skin will grow and merge into one another, covering large areas.
  • Disorders of the fingernails and toenails, including discolouration and pitting of the nails. The nails may also begin to crumble or detach from the nail bed.
  • Plaques or crust on the scalp.
  • Small areas of bleeding where the involved skin is scratched.

Who gets psoriasis?

It is relatively common affecting around 2% of people in the UK. Men and women are equally likely to develop psoriasis - but it is more common under 35.

How can I find out if I have psoriasis?

If you have a rash that is not healing, seek medical advice for evaluation of the rash to determine if it is psoriasis.

A doctor or specialist dermatologist will diagnose psoriasis based on how it looks. They may also arrange for a skin sample - called a biopsy - to be taken and sent for laboratory testing. This should help determine the type of psoriasis so that appropriate treatment can be given.

Psoriasis complications

Psoriasis can also be associated with psoriatic arthritis, which causes pain and swelling in the joints. The Psoriasis Association estimates that between 5% and 7% of people with psoriasis have psoriatic arthritis, but this figure rises to about 40% in people who have severe psoriasis. The NHS estimates that between 20 to 40% of people with psoriasis will also develop psoriatic arthritis.

If psoriatic arthritis is suspected, a referral to an arthritis specialist (rheumatologist) will usually be arranged.

The effect psoriasis has on a person's appearance and the discomfort can affect self-esteem and lead to mental health issues.

The condition is also linked to a higher risk of developing type 2 diabetes and heart problems.

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