Psoriasis – A Guide

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Psoriasis is a skin condition that causes red, flaky, crusty patches of skin covered with silvery scales. The condition is not infectious and most people are affected only in small patches on their body.

Symptoms of psoriasis
Causes of psoriasis
Being diagnosed with psoriasis
Treating psoriasis
living with psoriasis


It affects around 2% of people in the UK. It can start at any age, but most often develops between the ages of 11 and 45.

The severity of psoriasis varies greatly from person to person. For some people it is just a minor irritation, but for others it has a major impact on their quality of life.

Psoriasis is a long-lasting disease (chronic) that can return at any time. There may be times when you have no symptoms or very mild symptoms followed by times when the symptoms are severe.


There is no cure for psoriasis, but there is a range of treatments that can improve your symptoms and the appearance of the affected skin patches.

What happens to the skin?

Skin cells have a life cycle. Your body produces new cells in your deepest skin level. These skin cells gradually move up through the layers of your skin until they reach the outermost level. Then they die and flake off. The whole process normally takes around 21 to 28 days.

In psoriasis, this process speeds up and only takes two to six days. As a result, cells that are not fully mature build up rapidly on the surface of the skin, causing red, flaky, crusty patches covered with silvery scales. These patches are easily shed. It can occur on any part of the body, but is most common on the elbows, knees, lower back and scalp. It can cause itching and burning.

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Symptoms of psoriasis

Most cases of psoriasis go through cycles, causing problems for a few weeks or months then easing or stopping.There are several different types of psoriasis. Normally, people have only one form of psoriasis at a time, although two different types can occur together. One type may change to another type or may become more severe.

Common types of psoriasis

Common types of psoriasis are:

  • Plaque psoriasis.
    This is the most common form, accounting for 80% of cases. Its symptoms are dry, red skin lesions, known as plaques, that are covered in silver scales. They normally appear on your elbows, knees, scalp and lower back but can appear anywhere on your body. The plaques can be itchy, sore or both. In severe cases, the skin around your joints may crack and bleed. Guttate psoriasis. This normally occurs following a streptococcal throat infection and is more common among children and teenagers. It causes small (less than 1cm or 1/3 inch) drop-shaped sores on your chest, arms, legs and scalp. There is a good chance that guttate psoriasis will disappear completely, but some people go on to develop plaque psoriasis. Scalp psoriasis. This can occur on parts of your scalp or on the whole scalp. It causes red patches of skin covered in thick silvery-white scales. Some people find scalp psoriasis extremely itchy, while others have no discomfort. In extreme cases it can cause hair loss, although this is usually only temporary. Nail psoriasis. This affects your nails, causing them to develop tiny dents or pits, become discoloured and grow abnormally. Often nails can become loose and separate from your nail bed. In severe cases, your nails may crumble.
  • Inverse (flexural) psoriasis.
    This affects areas of the skin that are in folds or creases, such as the armpits, groin and the skin between the buttocks and under the breasts. It can cause large, smooth red patches in some or all of these areas. Inverse psoriasis is made worse by friction and sweating, so it can be particularly uncomfortable in hot weather.

Pustular psoriasis

Pustular psoriasis is a rarer type of psoriasis that causes pus-filled blisters (pustules) to appear on your skin. Different types of pustular psoriasis affect different parts of the body:

  • Generalised pustular psoriasis or von Zumbusch psoriasis.
    This causes pustules on a wide area of skin, which develop very quickly. The pus consists of white blood cells and is not infected. The pustules dry and peel off within a couple of days, leaving the skin shiny and smooth. The pustules may reappear every few days or weeks in cycles. During the start of these cycles, von Zumbusch psoriasis can cause fever, chills, weight loss and fatigue. Palmoplantar pustular psoriasis. This causes pustules to appear on the palms of your hands and the soles of your feet. The pustules gradually develop into circular brown scaly spots, which then peel off. Pustules may reappear every few days or weeks.
  • Acropustulosis.
    This causes pustules to appear on your fingers and toes. The pustules then burst, leaving bright red areas that may ooze or become scaly. These may lead to painful nail deformities.

Erythrodermic psoriasis

Erythrodermic psoriasis is a rare form of psoriasis that affects nearly all of the skin on the body. This can cause intense itching or burning. Erythrodermic psoriasis can cause your body to lose proteins and fluid. This can lead to serious illnesses such as infection, dehydration, heart failure, hypothermia and malnutrition.

Causes of psoriasis

The exact cause of psoriasis is unknown, but it is known that your immune system plays a part. Your immune system is your body’s defence against disease and helps to fight infection. If you have psoriasis, T cells (which exist in the blood and are part of your body’s defence system) start to attack healthy skin cells by mistake. This triggers the immune system to produce new skin cells and also more T cells.The cycle of skin cell production becomes faster and faster. Skin cells are created and then die in the space of five to six days, rather than the normal 28 days. The dead skin cells build up on the surface of your skin in thick, scaly patches.


Psoriasis runs in families. One in three people with psoriasis has a close relative with the condition.

The exact role that genetics plays in causing psoriasis is unclear. Research studies have shown that many different genes are linked to the development of psoriasis. It is likely that different combinations of genes may make people more vulnerable to the condition. However, having these genes does not necessarily mean that you will develop it.

Psoriasis triggers

Many people with psoriasis find that their symptoms start or become worse because of a certain event, known as a trigger. Knowing your triggers may mean you can avoid a flare-up of psoriasis. Common triggers include:

  • An injury to your skin such as a cut, scrape, insect bite or sunburn (this is known as the Koebner response). Alcohol. Smoking. Stress. Certain medicines such as lithium, some antimalarial medicines, anti-inflammatory medicines including ibuprofen, ACE inhibitors (used to treat high blood pressure) and beta blockers (used to treat congestive heart failure).Throat infections. In some people, usually children and young adults, a form of psoriasis called guttate psoriasis (which causes smaller pink patches, often without a lot of scaling) develops after a streptococcal throat infection. However, most people who have streptococcal throat infections do not develop psoriasis.
  • Other immune disorders. Diseases of the immune system, such as the HIV infection, can cause psoriasis to flare up or to appear for the first time.

Being diagnosed with psoriasis

There is no blood test for psoriasis. Usually, your doctor will make the diagnosis from the appearance of your skin. In rare cases, a small sample of skin, called a biopsy, will be sent to the laboratory for examination under a microscope. This will determine the exact type of psoriasis and will rule out other skin disorders, such as seborrhoeic dermatitis, lichen planus, lichen simplex and pityriasis rosea.

If your doctor suspects you have psoriatic arthritis, which is sometimes a complication of psoriasis, you may be referred to a rheumatologist, who specialises in arthritis. You may have blood tests to rule out other conditions and X-rays of the affected joints may be taken.

Treating psoriasis

Most people with psoriasis can be treated by their GP. Your GP may refer you to a dermatologist (skin specialist) and their team in a hospital if symptoms are particularly severe or have not responded well to previous treatments.

There is no cure for psoriasis. However, treatment is usually effective and will control the condition by clearing or reducing the patches of psoriasis.

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Treatments are determined by the type and severity of your psoriasis and the area of the skin affected. Your GP will probably start with a mild treatment, such as topical creams (i.e. applied to the skin), and then move on to stronger treatments if necessary. There are a wide range of treatment options for psoriasis, but identifying which treatment is most effective can be difficult. Talk to your GP if you feel a treatment is not working or you are having uncomfortable side effects.Treatments fall into three categories:

  • Topical: creams and ointments that are applied to your skin. Phototherapy: your skin is exposed to certain types of ultraviolet light.
  • Oral and injected medication: medicine that reduces the production of your skin cells, including biological treatments that target specific parts of the immune system.

Often, different types of treatment are often used in combination.Your treatment for psoriasis may need to be reviewed regularly. You may want to consider making a care plan (an agreement between you and your health professional) as this can help you manage your day-to-day health.

Living with psoriasis


Self care is an essential part of your daily life. It involves taking responsibility for your own health and wellbeing with support from the people involved in your care. Self care includes taking action to stay fit and maintain good physical and mental health, prevent illness or accidents and care more effectively for minor illnesses and long-term conditions.

People with long-term conditions can benefit enormously from self care. They can live longer, have less pain, anxiety, depression and fatigue, have a better quality of life, and be more active and independent. Having a care plan will help you manage your treatment so that it fits with your lifestyle.

Keep up your treatment

It is important to use your treatment as prescribed, even if your psoriasis improves. Continuous treatment can help to prevent flare-ups. If you have any questions or concerns about your treatment or any side effects, talk to your GP or healthcare team.

Regular reviews

Because psoriasis can be a long-term condition, you may be in regular contact with your healthcare team. Discuss your symptoms or concerns with them as the more the team knows, the more they can help you.

Help with health costs

If you regularly pay for more than three prescriptions a month, you may save money with a prescription prepayment certificate (PPC). To check the cost of a PPC, call 0845 850 0030 or check leaflet HC12 (available in some pharmacies or GP surgeries).

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