Psoriasis is a skin condition that causes red, flaky, crusty patches of skin covered with silvery scales.

These patches normally appear on your elbows, knees, scalp and lower back but can appear anywhere on your body. Most people are only affected in small patches. In some cases, the patches can be itchy or sore.

Psoriasis it can start at any age, but most often develops in adults under 35 years old. The condition affects men and women equally.

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

Psoriasis is a long-lasting (chronic) disease that usually involves periods when you have no symptoms or mild symptoms, followed by periods when symptoms are more severe.

When to seek medical advice

You should see your GP if you think you may have psoriasis. They can often diagnose the condition based on the appearance of your skin.

Further tests are usually only necessary if the diagnosis is uncertain, in which case you may be referred to a specialist in skin conditions called a dermatologist.

Why it happens

Psoriasis occurs when the process by which the body produces skin cells is accelerated. Skin cells are normally made and replaced every three to four weeks, but in psoriasis this process only lasts about three to seven days. The resulting build-up of skin cells is what creates the patches associated with psoriasis.

Although the process is not fully understood, it is thought the increased production of skin cells is related to a problem with the immune system. The immune system is your body's defence against disease and infection, but in people with psoriasis it attacks healthy skin cells by mistake.

As psoriasis can run in families, there is also thought to be a genetic element to psoriasis. However, the exact role that genetics plays in causing psoriasis is unclear.

Many people's psoriasis symptoms start or become worse because of a certain event, known as a trigger. Possible triggers of psoriasis include an injury to your skin, throat infections and using certain medicines.

The condition is not contagious so it cannot be spread from person to person.

Treating psoriasis

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

In most cases, the first treatment used will be a topical treatment, such as vitamin D analogues or topical corticosteroids. Topical treatments are creams and ointments applied to the skin.

If these are ineffective or your condition is more severe, a treatment called phototherapy may be used. Phototherapy involves exposing your skin to certain types of ultraviolet light.

In the most severe cases where other treatments are ineffective, systemic treatments may be used. These are oral or injected medicines that work throughout the whole body.

Living with psoriasis

Although psoriasis is just a minor irritation for some people, the condition can sometimes have a significant impact on your life.

For example, some people with psoriasis have low-self esteem due to the affect the condition can have on your physical appearance. It is also quite common for someone with psoriasis to develop tenderness, pain and swelling in the joints and connective tissue. This is known as psoriatic arthritis.

Speak to your GP or healthcare team if you have psoriasis and you have any concerns about your physical and mental wellbeing. They can offer advice and further treatment if necessary. There are also a number of support groups for people with psoriasis, such as The Psoriasis Association, where you can speak to other people with the condition.

Symptoms of psoriasis 

Most cases of psoriasis go through cycles, causing problems for a few weeks or months before easing or stopping.

There are several different types of psoriasis. Many people have only one form of psoriasis at a time, although two different types can occur together. One type may change into another type or may become more severe. You should see your GP if you think you may have psoriasis.


Common types of psoriasis

Plaque psoriasis

This is the most common form, accounting for about 90% of cases. Its symptoms are dry, red skin lesions, known as plaques, which 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. 

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

In about half of all people with psoriasis, the condition affects the nails. Psoriasis can cause your nails to develop tiny dents or pits, become discoloured or grow abnormally. Often nails can become loose and separate from your nail bed. In severe cases, your nails may crumble.

Guttate psoriasis

Guttate psoriasis 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 after a few weeks, but some people go on to develop plaque psoriasis.

This type of psoriasis sometimes occurs after a streptococcal throat infection and is more common among children and teenagers.

Inverse (flexural) psoriasis

This affects folds or creases in your skin, such as the armpits, groin, 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 a sign of infection. 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.


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 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 further problems such as infection, dehydration, heart failure, hypothermia and malnutrition.

Causes of psoriasis 

Psoriasis occurs when skin cells are replaced more quickly than usual. It is not known exactly why this happens.

Your body produces new cells in the deepest layer of your skin level. These skin cells gradually move up through the layers of skin until they reach the outermost level. Then they die and flake off. This whole process normally takes around three to four weeks.

In people with psoriasis, this process only takes about three to seven 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.

It's thought that the skin cells are replaced quickly in people with psoriasis due to a problem with the immune system.

Problems with the immune system

Your immune system is your body's defence against disease and it helps fight infection. One of the main types of cell used by the immune system is called a T-cell.

T-cells normally travel through the body to detect and fight things like infections, but in people with psoriasis they start to attack healthy skin cells by mistake. This causes the deepest layer of skin to produce new skin cells more quickly than usual, which in turn triggers the immune system to produce more T-cells.

It is not known what exactly causes this problem with the immune system, although certain genes and environmental triggers may play a role.


Psoriasis runs in families. One in three people with psoriasis has a close relative with the condition. However, the exact role that genetics plays in causing psoriasis is unclear. Research studies have shown  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 you will develop it.

Psoriasis triggers

Many people's psoriasis symptoms start or become worse because of a certain event, known as a trigger. Knowing your triggers may help you to avoid a flare-up. Common triggers include:

an injury to your skin such as a cut, scrape, insect bite or sunburn (this is known as the Koebner response)

drinking excessive amounts of alcohol



hormonal changes, particularly in women (for example during puberty and the menopause)

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, although most people who have streptococcal throat infections do not develop psoriasis

other immune disorders, such as HIV, which cause psoriasis to flare up or to appear for the first time

Psoriasis is not contagious so it cannot be spread from person to person.

Diagnosing psoriasis  

Usually, your doctor will make a diagnosis of psoriasis based on 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.

You may be referred to a dermatologist (a specialist in diagnosing and treating skin conditions) if your doctor is uncertain about your diagnosis or your condition is severe.

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

Treating psoriasis 

There is no cure for psoriasis, but treatment will usually help keep the condition under control.

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

Treatments are determined by the type and severity of your psoriasis and the area of skin affected. Your doctor will probably start with a mild treatment, such as topical creams (which are applied to the skin), and then move on to stronger treatments if necessary.

A wide range of treatments are available for psoriasis, but identifying which treatment is most effective can be difficult. Talk to your doctor if you feel a treatment is not working or you have 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

systemic - oral and injected medications that work throughout the entire body 

Often, different types of treatment are used in combination.

Your treatment for psoriasis may need to be reviewed regularly. You may want to make 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 

Although psoriasis is just a minor irritation for some people, the condition can have a significant impact on your life.

If you have psoriasis, you may find the following advice helpful:

Self care

Self care is an essential part of your daily life. It involves taking responsibility for your own health and wellbeing with support from those involved in your care. Self care includes staying fit and maintaining good physical and mental health, preventing illness or accidents and caring 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, a better quality of life, and be more active and independent. Having a care plan will help you manage your treatment so it fits your lifestyle. 

Keep up your treatment

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

Because psoriasis is usually 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.

Healthy eating and exercise

People with psoriasis have a slightly higher risk of developing diabetesand cardiovascular disease, although it is not known why. Regular exercise and a healthy diet are recommended for everyone, not just people with psoriasis, because they can help prevent many of these conditions.

Eating a healthy, balanced diet and exercising regularly can also relieve stress, which may help improve your psoriasis.

Emotional impact of psoriasis

Due to the unpleasant effects that psoriasis can have on physical appearance, low self-esteem and anxiety are common among people with the condition. This can lead to depression, especially if the psoriasis gets worse.

Your GP or dermatologist will understand the psychological and emotional impact of psoriasis, so talk to them about your concerns or anxieties. If necessary, they can discuss the different treatment options available.

Psoriatic arthritis

Some people with psoriasis develop psoriatic arthritis. This causes tenderness, pain and swelling in the joints and connective tissue,as well as stiffness. It commonly affects the ends of the fingers and toes. In some people, it affects the lower back, neck and knees. Most people develop psoriatic arthritis after the onset of psoriasis, but about 20% develop it before they are diagnosed with psoriasis.

There is no single test for psoriatic arthritis. It is normally diagnosed using a combination of methods, including looking at your medical history, physical examinations, blood tests, X-rays and MRI scans. If you have psoriasis, you will usually have an annual assessment to look for signs of psoriatic arthritis.

If your doctor suspects you have psoriatic arthritis, you will usually be referred to a specialist called a rheumatologist so you can be treated with anti-inflammatory or anti-rheumatic medicines.


Psoriasis does not affect fertility and women with psoriasis can have a normal pregnancy and a healthy baby. Some women find their psoriasis improves during pregnancy, but for others it gets worse.

Talk to your healthcare team if you are thinking of having a baby. Some treatments for psoriasis can be harmful to a developing baby, so use contraception while taking them. This can apply to both men and women, depending on the medication. Your healthcare team can suggest the best ways to control your psoriasis before you start trying for a family.

Talk to others

Many people with psoriasis have found that getting involved in support groups helps. Support groups can increase your self-confidence, reduce feelings of isolation, and give you practical advice about living with the condition.