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 with small patches. In some cases, the patches can be itchy or sore.
Psoriasis affects around 2% of people in the UK. 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's just a minor irritation, but for others it can have 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.
Read more about the symptoms of psoriasis .
Why it happens
People with psoriasis have an increased production of skin cells.
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 isn't fully understood, it's thought to be related to a problem with the immune system. The immune system is your body's defence against disease and infection, but for people with psoriasis, it attacks healthy skin cells by mistake.
Psoriasis can run in families, although 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 isn't contagious, so it can't be spread from person to person.
Read more about the causes of psoriasis .
How psoriasis is diagnosed
A GP can often diagnose 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 determines the exact type of psoriasis and rules 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 if 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 (a doctor 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.
There's no cure for psoriasis, but a range of treatments can improve symptoms and the appearance of 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 aren't effective, 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 severe cases, where the above treatments are ineffective, systemic treatments may be used. These are oral or injected medicines that work throughout the whole body.
Read more about treating psoriasis .
Living with psoriasis
Although psoriasis is just a minor irritation for some people, it can have a significant impact on quality of life for those more severely affected.
For example, some people with psoriasis have low self-esteem because of the effect the condition has on their appearance. It's also quite common 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 support groups for people with psoriasis, such as The Psoriasis Association, where you can speak to other people with the condition.
Read more about living with psoriasis .
Want to know more?
- The Psoriasis Association: what is psoriasis?
- PAPAA: about 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 doctor if you think you may have psoriasis.
Common types of 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.
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.
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 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 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 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.
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 triggers the immune system to produce new skin cells more quickly than usual, as well as 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.
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.
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.
See living with psoriasis for more information about psoriatic arthritis.
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.
Topical treatments are usually the first treatments used for mild to moderate psoriasis. These are creams and ointments you apply to affected areas. They are all that some people need to control their condition.
If you have scalp psoriasis, a combination of shampoo and ointment may be recommended.
Topical corticosteroids are commonly used to treat mild to moderate psoriasis in most areas of the body. The treatment works by reducing inflammation. This slows the production of skin cells and reduces the symptoms of itching.
Topical corticosteroids range in strength from mild to very strong. Only use topical corticosteroids when recommended by your doctor. Stronger topical corticosteroids can be prescribed by your doctor and should only be used on small areas of skin or on particularly thick patches. Overusing topical corticosteroids can lead to skin thinning.
Vitamin D analogues
Vitamin D analogue creams are commonly used along with, or instead of, topical corticosteroids for mild to moderate psoriasis affecting areas such as the limbs, trunk or scalp. They work by slowing the production of skin cells. They also have an anti-inflammatory effect.
Types of vitamin D analogues include calcipotriol, calcitriol and tacalcitol. There are very few side effects, as long as you do not use more than the recommended amount.
Calcineurin inhibitors, such as tacrolimus and pimecrolimus, are medicines that reduce the activity of the immune system and help to reduce inflammation. They are sometimes used to treat psoriasis affecting sensitive areas (such as the scalp, the genitals and folds in the skin) if topical corticosteroids are ineffective.
These medications can cause skin irritation or a burning and itching sensation when they are started, but this will usually improve within a week.
Coal tar is a thick, heavy oil and is probably the oldest treatment for psoriasis. How it works is not exactly known, but it can reduce scales, inflammation and itchiness. It may be used to treat psoriasis affecting the limbs, trunk or scalp if other topical treatments are ineffective.
Coal tar can stain clothes and bedding and has a strong smell. It can be used in combination with phototherapy (see below).
Dithranol has been used for over 50 years to treat psoriasis. It has been shown to be effective in suppressing production of skin cells and has few side effects. However, it can burn if too concentrated.
It is typically used as a short-term treatment for psoriasis affecting the limbs or trunk under hospital supervision as it stains everything it comes into contact with, including skin, clothes and bathroom fittings. It is applied to your skin (while wearing gloves) and left for 10 to 60 minutes before being washed off.
Dithranol can be used in combination with phototherapy (see below).
Phototherapy uses natural and artificial light to treat psoriasis. Artificial light therapy can be given in hospitals and some specialist centres, usually under the care of a dermatologist. These treatments are not the same as using a sunbed.
Ultraviolet B (UVB) phototherapy uses a wavelength of light invisible to human eyes. The light slows down the production of skin cells and is an effective treatment for some types of psoriasis that have not responded to topical treatment. Each session only takes a few minutes but you may need to go to hospital two or three times a week for six to eight weeks.
Psoralen plus ultraviolet A (PUVA)
For this treatment, you will first be given a tablet containing compounds called psoralens, or psoralen may be applied directly to the skin. This makes your skin more sensitive to light. Your skin is then exposed to a wavelength of light called ultraviolet A (UVA). This light penetrates your skin more deeply than ultraviolet B light.
This treatment may be used if you have severe psoriasis that has not responded to other treatment. Side effects of the treatment include nausea, headaches, burning and itchiness. You may need to wear special glasses for 24 hours after taking the tablet to prevent the development of cataracts. Long-term use of this treatment is not encouraged as it can increase your risk of developing skin cancer.
Combination light therapy
Combining phototherapy with other treatments often increases its effectiveness. Some doctors use UVB phototherapy in combination with coal tar, as the coal tar makes the skin more receptive to light. Combining UVB phototherapy with dithranol cream may also be effective (this is known as Ingram treatment).
If your psoriasis is severe or other treatments have not worked, you may be prescribed systemic treatments by a specialist. Systemic treatments are treatments that work throughout the entire body.
These medications can be very effective in treating psoriasis but they all have potentially serious side effects. All the systemic treatments for psoriasis have benefits and risks. Before starting treatment, talk to your doctor about your treatment options and any risks associated with them.
There are two main types of systemic treatment, called non-biological (usually given as tablets or capsules) and biological (usually given as injections). These are described in more detail below.
Methotrexate can help control psoriasis by slowing down the production of skin cells and suppressing inflammation. It is usually taken once a week.
Methotrexate can cause nausea and may affect production of blood cells. Long-term use can cause liver damage. People who have liver disease should not take methotrexate and you should not drink alcohol when taking it.
Methotrexate can be very harmful to a developing baby, so it is important that women use contraception and do not become pregnant while they take this drug and for three months after they stop. Methotrexate can also affect the development of sperm cells, so men should not father a child during treatment and for three weeks afterwards.
Ciclosporin is a medicine that suppresses your immune system (immunosuppressant). It was originally used to prevent transplant rejection but has proved effective in treating all types of psoriasis. It is usually taken daily.
Ciclosporin increases your chances of kidney disease and high blood pressure, which will need to be monitored.
Acitretin is an oral retinoid that reduces production of skin cells. It is used to treat severe psoriasis that has not responded to other non-biological systemic treatments. It is usually taken daily.
Acitretin has a wide range of side effects, including dryness and cracking of the lips, dryness of the nasal passages and, in rarer cases, hepatitis.
Acitretin can be very harmful to a developing baby, so it is important that women use contraception and do not become pregnant while they take this drug and for two years after they stop taking it. However, it is safe for a man taking acitretin to father a baby.
Biological treatments reduce inflammation by targeting overactive cells in the immune system. These treatments are usually used if you have severe psoriasis that has not responded to other treatments, or if you cannot use other treatments.
Etanercept is injected twice a week and you will be shown how to do this. If there is no improvement in your psoriasis after 12 weeks, the treatment will be stopped.
The main side effect of etanercept is a rash where the injection is given. However, as etanercept affects the whole immune system, there is a risk of serious side effects including severe infection. If you had tuberculosis in the past, there is a risk it may return. You will be monitored for side effects during your treatment.
Adalimumab is injected once every two weeks and you will be shown how to do this. If there is no improvement in your psoriasis after 16 weeks, the treatment will be stopped.
Adalimumab can be harmful to a developing baby, so it is important that women use contraception and do not become pregnant while they take this drug and for five months after the treatment finishes.
The main side effects of adalimumab include headaches, a rash at the injection site and nausea. However, as adalimumab affects the whole immune system, there is a risk of serious side effects including severe infections. You will be monitored for side effects during your treatment.
Infliximab is given as a drip (infusion) into your vein at the hospital. You will have three infusions in the first six weeks, then one infusion every eight weeks. If there is no improvement in your psoriasis after 10 weeks, the treatment will be stopped.
The main side effect of infliximab is a headache. However, as infliximab affects the whole immune system, there is a risk of serious side effects including severe infections. You will be monitored for side effects during your treatment.
Ustekinumab is injected at the beginning of treatment, then again four weeks later. After this, injections are every 12 weeks. If there is no improvement in your psoriasis after 16 weeks, the treatment will be stopped.
The main side effects of ustekinumab are a throat infection and a rash at the injection site. However, as ustekinumab affects the whole immune system, there is a risk of serious side effects including severe infections. You will be monitored for side effects during your treatment.
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 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 doctor 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 diabetes and 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 doctor 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.
Between 10% and 20% of 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.