What is psoriasis?

Plaque psoriasis is an autoimmune disease that primarily affects the skin. For people with any type of autoimmune disease, the immune system does not work properly and attacks the body, instead of protecting it.

In plaque psoriasis it attacks the skin causing red, flaky, dry patches, most often on the elbows, knees or scalp.

Who is affected by psoriasis?

No one knows exactly what causes psoriasis, but genetic factors are involved. People with psoriasis often also have a close relative with the condition.

Anyone could develop psoriasis, and it is relatively common. Around 8 in every 100 people worldwide develop plaque psoriasis (the most common form of psoriasis).

Although psoriasis can begin at any age, diagnosis is more commonly seen in people aged between 15-20 years and 55-60 years.

Psoriasis can be called either Type I or Type II, depending on age at diagnosis; Type I begins before the age of 40, whereas Type II begins after the age of 40.

What are the symptoms of psoriasis?

The intensity of psoriasis symptoms vary from mild to severe. There may be periods when these symptoms get better. In other periods they get much worse; these periods are called flares. These symptoms also vary considerably among people with psoriasis, as the condition can have different types.

In psoriasis, skin cells are produced more quickly than in people without psoriasis. The skin cells build up on the surface of the skin, and this leads to the symptoms.

  • The main symptom of plaque psoriasis is plaques, which are dry, red skin lesions, covered with white-silvery scales of dead cells
  • Scalp psoriasis can affect part or all of the scalp, causing red patches of skin covered in thick silvery white scales. It can be very itchy
  • Nail psoriasis can affect up to half of all people with psoriasis. The nails develop tiny dents or pits and become discoloured. They can crumble, or become loose

Additional information

You can find additional information about psoriasis following these links:

NHS Choices:

Psoriasis Association:

Psoriasis and Psoriatic Arthritis Alliance: