Psoriasis – an overview

What are the aims of this leaflet?

The British Association of Dermatologists offers three patient information leaflets on psoriasis. This leaflet has been written to provide you with an overview of psoriasis. It tells you what psoriasis is, what causes it, what can be done about it, and where you can find out more about it. The two other leaflets (Topical treatments for psoriasis and Treatment of moderate and severe psoriasis) give more details about the different types of treatment. 

What is psoriasis? 

Psoriasis is a common, long term skin condition that comes and goes throughout your lifetime. It happens due to immune system over-activity.

Psoriasis is not infectious; therefore, you cannot catch it from someone else. It does not scar the skin, although sometimes it can cause temporary changes of skin colour. Although psoriasis is a long-term condition there are many effective treatments available to keep it under good control.

Psoriasis affects about 1 in 50 people. It may occur at any age from puberty onwards, but rarely can affect younger children.

Psoriasis affects the skin and may affect the nails. It is also associated with a condition called psoriatic arthritis in about 1 in 5 people. Psoriatic arthritis is an inflammatory condition of the joints which can cause pain and sometimes joint damage. The pain can be quite variable but is typically worse in the morning and after rest periods. It may be associated with hot and swollen joints. Individuals may also report stiffness in the lower back. It is important to identify any possible joint pain early to help alleviate the symptoms and reduce long-term complications associated with joint symptoms. This should be managed by a rheumatologist who works with your dermatologist and/or your GP.

Psoriasis is considered to be one of a number of immune-mediated inflammatory diseases (IMID). Other IMIDs include ankylosing spondylitis, psoriatic arthritis and inflammatory bowel disease (IBD).

People affected by psoriasis and other IMIDs may also have a higher risk of experiencing other health problems. These can include things like feeling anxious or depressed, heart disease, stroke, diabetes, obesity, blood clots, high cholesterol, and high blood pressure. While we do not fully understand why these conditions are connected, scientists are actively studying this relationship.

Understanding this connection can help individuals take steps to identify and address these concerns. It is important to make informed choices about your lifestyle and consider using health screening services provided by your doctor (GP). This way, you can take proactive measures to manage your overall health and well-being.

What causes psoriasis?

The cause of psoriasis is unknown. It is believed that both genetic and environmental factors play a role in its development. It is thought that something triggers the immune system making it more active. This then leads to a long-lasting (chronic) inflammation that causes the skin cells to reproduce too quickly.

Triggers can include infections, certain medications, ultraviolet (UV) light and low-grade inflammation. For many people, psoriasis can get better with exposure to UV light (a type of light that comes from the sun and some artificial sources such as sunbeds). However, for others, UV light can worsen psoriasis. Changes in the body, such as pregnancy, can make psoriasis better, but not always.

The onset and severity of psoriasis has also been linked to alcohol consumption, being overweight, smoking, and stress. All of these factors are known to cause a type of mild (low-grade) inflammation in the body. However, not everyone who smokes, drinks alcohol or is overweight will develop psoriasis.

We do not fully understand why these triggers lead to psoriasis, and it may vary from person to person.

Is psoriasis hereditary? 

Yes, there is a strong family link to psoriasis. If you have a family member affected by psoriasis, you are more likely to be affected by it too, due to shared genes. The way psoriasis is inherited is complex and not completely understood.

What does psoriasis look and feel like?

  • The skin of a person affected by psoriasis can appear pink, red, or darker, but in richly pigmented skin, this may not be visible. The skin also appears scaly – scales are typically of silvery colour.
  • The flakes and scales can be visible on dark coloured clothing and may cause anxiety. Many people with psoriasis prefer to avoid dark clothing so that the flakes are not obvious.
  • Psoriasis may affect any part of the body, but commonly affected areas are the outside surface of the elbow and knee, belly button (umbilicus) and scalp.
  • Psoriasis can be itchy and painful. Certain sites such as the scalp, lower legs and groin can be particularly itchy. If psoriasis affects the hands and feet, painful fissures (cracks) can develop, and these can affect use of the hands and walking. Severe psoriasis on the body can also develop cracks which are painful and can bleed.
  • Psoriasis can affect the nails which may be painful and can cause lifting of the nail, pitting of the nail or disfigurement of the nail. These changes can be painful and may affect dexterity – for example, they can limit the ability to do simple tasks, such as doing buttons up or picking small object up; they also can catch on clothing when getting dressed
  • When psoriasis affects certain areas of the body, quality of life may be very significantly impacted. These high impact sites include hands, face, scalp genitals and feet.
  • Psoriatic arthritis produces pain, swelling and stiffness in one or more joints, particularly in the morning. It can also affect connective tissue, ligaments and tendons. You must speak with your doctor if you need a referral to a rheumatologist.

Many people have just a few plaques but some individuals with moderate to severe psoriasis may have several plaques covering large areas of their body.

Several patterns of psoriasis are recognised:

  • Chronic plaque psoriasis is the most common type of psoriasis. Plaques (circular, scaly skin lesions) of psoriasis are usually present on the knees, elbows, trunk, scalp, behind ears and between the buttocks although other areas can be involved too.
  • Guttate psoriasis consists of small plaques of psoriasis scattered over the trunk and limbs. It can be caused by bacteria called streptococcus which can cause throat infections.
  • Palmoplantar psoriasis is psoriasis affecting the palms and soles. Psoriasis may appear at other sites too.
  • Pustular psoriasis is rare type of psoriasis where the plaques on the trunk and limbs are studded with tiny yellow pus filled spots. It can be localised or generalised and can flare rapidly necessitating hospital admission for treatment.
  • Flexural psoriasis affects the skin folds (armpits and groin) and may be seen alongside chronic plaque psoriasis or in isolation.
  • Erythrodermic psoriasis is a very severe form of psoriasis which affects nearly all of the skin and can sometimes require hospital admission for treatment.

Nail psoriasis is present in about half of people with psoriasis. The features of nail psoriasis are:

  • Pitting (indentations) and ridging of the surface of the nail
  • Salmon pink areas of discolouration under the nail
  • Lifting of the nails, and
  • Thickening and yellowing of the nails
  • Complete nail destruction.

How will psoriasis be diagnosed?

  • Psoriasis is usually diagnosed on the appearance and distribution of the plaques. Skin biopsy is rarely used.
  • Psoriatic arthritis is usually diagnosed by a rheumatologist, but your dermatologist or GP may ask you if you have any joint symptoms or ask you to complete a screening questionnaire.
  • In most people, skin psoriasis develops first. A small number of people, psoriasis can present with nail involvement only. Similarly, some people develop joint symptoms first before having skin symptoms. In most cases, it usually takes few years before you develop nail or joint symptoms.

How is psoriasis assessed?

Psoriasis should be assessed at diagnosis, before your first referral to a specialist, every time you see a specialist and to assess your response to treatment. Psoriasis may be assessed by your doctors using a variety of scores which measure the severity in your skin and joints, how psoriasis is affecting your mood and your activities of daily living and whether you are at risk of heart disease.

These scores include the PASI (Psoriasis Area and Severity Index) and DLQI (Dermatology Life Quality Index – a score that measures the impact of psoriasis on your quality of life). This assessment will be part of your specialist reviews and it will help monitor the effects of treatment on further or follow up visits.

Can psoriasis be cured?

There is no cure for psoriasis. However, there are several effective treatments available to keep psoriasis well controlled. Spontaneous (or sudden, unexpected) clearance of psoriasis may occur in some people.

How can psoriasis be treated?

Treatment of psoriasis depends upon your individual circumstances. Treatment applied to the surface of your skin (topical treatment) is sufficient alone in most people. For individuals with more extensive or difficult to treat psoriasis, ultraviolet light treatment (phototherapy), tablet treatment or injection treatment may be required. 

1. Topical treatments:

  • These include creams, ointments, gels, pastes, foams and lotions. Topical treatments are dealt with in more detail in another of our leaflets (Topical treatments for psoriasis).

2. Phototherapy:

  • Phototherapy is ultraviolet light delivered in a controlled way to treat psoriasis. A course of treatment usually takes about 8-10 weeks and will require treatment sessions two to three times a week. This usually means attending a Phototherapy Unit in a hospital.
  • Two types of light are used: narrowband ultraviolet B light (NB-UVB/TLO1) and ultraviolet A light (PUVA). A treatment called psoralen taken as a tablet or added to a bath before treatment is required for PUVA.

Further information on phototherapy is available in the following information leaflets:

3. Internal (systemic) treatments

Further details of these treatments can be found in the Treatments for moderate and severe psoriasis and individual drug patient information leaflets.

What can I do?

Remember that psoriasis is an inflammatory condition. Therefore, it is important to consider lifestyle changes that will help reduce chronic inflammation in the body. Here are some suggestions on what you can do:

Talk to your general practitioner (GP) or dermatologist about your psoriasis and how it impacts your daily life. Together, you can set treatment goals.

  • Work with your GP to manage risk factors for heart disease and stroke.
  • Adopt a healthy lifestyle by eating a balanced diet, trying to lose weight if needed, and exercising regularly.
  • If you smoke, quitting can be beneficial.
  • If you consume excessive alcohol, reducing your intake may help.
  • Find ways to reduce stress whenever possible.
  • Take your prescribed medications as directed by your GP or dermatologist.
  • If you experience joint pain, discuss it with your GP or dermatologist.
  • Inform your doctor if you notice any nail symptoms.
  • Keep your skin well moisturized to prevent dryness and cracking

Where can I get more information about psoriasis? 

Links to patient support groups: 

The Psoriasis Association

Tel: 01604 251620


Psoriasis and Psoriatic Arthritis Alliance (PAPAA)

Tel: 01923 672837


Weblinks to detailed leaflets:

Jargon Buster:

 This leaflet aims to provide accurate information about the subject and is a consensus of the views held by representatives of the British Association of Dermatologists: individual patient circumstances may differ, which might alter both the advice and course of therapy given to you by your doctor. 

This leaflet has been assessed for readability by the British Association of Dermatologists’ Patient Information Lay Review Panel. 






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