Psoriasis is an inflammatory skin disease causing patches of red, scaly skin.

By Wallace Health I Medically reviewed by Adrian Roberts.
Page last reviewed: October 2018 I Next review due: October 2023

What is psoriasis?

Psoriasis is a chronic (long-term) condition where your skin produces new cells too quickly and it becomes inflamed. Normally, skin cells are formed and shed every three to four weeks, but in psoriasis, skin cells are replaced in three to seven days. This forms red, flaky patches of skin which can be itchy and sore.

Psoriasis affects around 2% of people in the UK. It usually starts before 35, but can start at any age. The severity of symptoms varies between people, and symptoms can come and go – with periods where it’s worse, called flare-ups.

There are different types of psoriasis. The most common are:

  • Plaque psoriasis – affecting 80-90% of people with psoriasis, with red, scaly plaques throughout your body
  • Scalp psoriasis – occurring on your scalp
  • Nail psoriasis ­– causing your nails to grow abnormally and become discoloured, with pits or dents
  • Guttate psoriasis (raindrop) – small drop-shaped sores on your chest, limbs and scalp which can disappear completely or develop into plaque psoriasis
  • Inverse (flexural) psoriasis – red areas with minimal scaling in skin folders such as the armpits

The exact cause is unknown; however it’s not contagious or due to an infection.

Although there’s no psoriasis cure, there are many effective treatments which help to keep it under control.

How to tell if you have psoriasis

The main symptom of psoriasis is red or dark raised patches on your skin called plaques. These can be flaky, scaly, and itchy but not usually painful. They can appear anywhere, but most commonly on your elbows, knees and scalp. You may also experience itchy genitals.

Of all people with psoriasis, nearly half have nail problems such as pitting and ridging, and nearly a third will develop joint problems (psoriatic arthritis) – particularly if your symptoms are more severe.

Most people find their symptoms come and go periodically.

Talk to your doctor if you’re concerned about symptoms

You can book an appointment with a Spire private GP today.

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Diagnosis and tests for psoriasis

Your GP may be able to diagnose psoriasis by looking at your skin. Occasionally, a biopsy (a small sample) of skin is taken to look at under a microscope to identify the exact type of psoriasis or rule out other skin conditions.

Your GP may refer you to a dermatologist if your psoriasis is severe or to confirm a diagnosis.

If your GP suspects you have psoriatic arthritis, they may refer you to a rheumatologist (a doctor specialising in arthritis).

Causes of psoriasis

The exact cause of psoriasis is not yet known. It’s thought to be an autoimmune disease, where your immune system mistakenly attacks healthy parts of your body.

You’re also more likely to get it if you have a family history, suggesting a genetic link.

Psoriasis may be triggered or made worse by:

  • A skin injury
  • Hormonal changes
  • Infection
  • Stress
  • Sunlight
  • Using certain medications, smoking and alcohol

Common treatments for psoriasis

Treatments are aimed at reducing plaques as much as possible. During flare-ups, you may need different treatment to help keep it under control. Treatments don’t work for everybody, so you may need to try different ones until you find one that works for you.

Most often, your GP will start by prescribing topical treatments (creams, gels, etc.) which are applied to the skin. These include:

  • Moisturisers – can help improve plaques and prevent itch
  • Vitamin D based topical treatment – can help slow the rate of skin cell production
  • Steroid creams – to help reduce inflammation
  • Calcineurin inhibitors – reduce immune system activity and inflammation
  • Coal tar – an old remedy that reduces scales, inflammation and itchiness
  • Dithranol – suppresses skin cell production

If necessary, further treatments a dermatologist may recommend include:

  • Phototherapy – exposing your skin to certain types of UV light
  • Oral medications or injections that suppress inflammation – can be very effective but can have side effects so aren’t suitable for everyone

You should also avoid any triggers that can cause flare-ups.