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 3 to 4 weeks, but in psoriasis this process only lasts about 3 to 7 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.
You can find support and information from organisations like:
- Changing Faces - a charity for people who have a visible difference or facial disfigurement, who can be contacted on 0300 012 0275 for counselling and advice
- The Psoriasis Association - provides support groups for people with psoriasis where you can speak to other people with the condition
Symptoms of psoriasis
Psoriasis typically causes patches of skin that are dry, red and covered in silver scales. Some people find their psoriasis causes itching or soreness.
There are several different types of psoriasis. Many people have only one form of psoriasis at a time, although 2 different types can occur together. One type may change into another type, or become more severe.
Most cases of psoriasis go through cycles, causing problems for a few weeks or months before easing or stopping.
You should see your GP if you think you may have psoriasis.
Common types of psoriasis
Plaque psoriasis (psoriasis vulgaris)
This is the most common form, accounting for about 80% 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. Nails can often 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's 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, leading 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's not known exactly why this happens, but research suggests it's caused by a problem with the immune system.
Your body produces new skin cells in the deepest layer of skin. 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 3 to 4 weeks.
In people with psoriasis, this process only takes about 3 to 7 days. As a result, cells that aren't fully mature build up rapidly on the surface of the skin, causing red, flaky, crusty patches covered with silvery scales.
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 invading germs such as bacteria, 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's 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. 1 in 3 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's likely that different combinations of genes may make people more vulnerable to the condition. However, having these genes doesn't necessarily mean you'll 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 develops after a streptococcal throat infection (although most people who have streptococcal throat infections don't develop psoriasis)
- other immune disorders, such as HIV, which cause psoriasis to flare up or to appear for the first time
Psoriasis isn't contagious, so it can't be spread from person to person.
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 isn't working or you have uncomfortable side effects.
Treatments fall into 3 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.
The various treatments for psoriasis are outlined below. You can also read a summary of the pros and cons of the treatments for psoriasis, allowing you to compare your treatment options.
Topical treatments are usually the first treatments used for mild to moderate psoriasis. These are creams and ointments you apply to affected areas.
Some people find that topical treatments are all they need to control their condition, although it may take up to 6 weeks before there's a noticeable effect.
If you have scalp psoriasis, a combination of shampoo and ointment may be recommended.
Emollients are moisturising treatments applied directly to the skin to reduce water loss and cover it with a protective film. If you have mild psoriasis, an emollient is probably the first treatment your GP will suggest.
The main benefit of emollients is to reduce itching and scaling. Some topical treatments are thought to work better on moisturised skin. It's important to wait at least half an hour before applying a topical treatment after an emollient.
Emollients are available as a wide variety of products and can be bought over the counter from a pharmacy or prescribed by your GP, nurse or health visitor.
Steroid creams or ointments
Steroid creams or ointments (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 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 steroid creams 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.
Examples of vitamin D analogues are calcipotriol, calcitriol and tacalcitol. There are very few side effects, as long as you don't use more than the recommended amount.
Calcineurin inhibitors, such as tacrolimus and pimecrolimus, are ointments or creams that reduce the activity of the immune system and help to reduce inflammation. They're sometimes used to treat psoriasis affecting sensitive areas (such as the scalp, the genitals and folds in the skin) if steroid creams aren't effective.
These medications can cause skin irritation or a burning and itching sensation when they're started, but this usually improves within a week.
Coal tar is a thick, heavy oil and is probably the oldest treatment for psoriasis. How it works isn't 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 aren't effective.
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 the production of skin cells and has few side effects. However, it can burn if too concentrated.
It's 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's 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 aren't the same as using a sunbed.
Ultraviolet B (UVB) phototherapy uses a wavelength of light that is invisible to human eyes. The light slows down the production of skin cells and is an effective treatment for some types of psoriasis that haven't responded to topical treatments. Each session only takes a few minutes, but you may need to go to hospital 2 or 3 times a week for 6 to 8 weeks.
Psoralen plus ultraviolet A (PUVA)
For this treatment, you'll 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 hasn't 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 isn't 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 haven't 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 2 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 to control psoriasis by slowing down the production of skin cells and suppressing inflammation. It's usually taken once a week.
Methotrexate can cause nausea and may affect the production of blood cells. Long-term use can cause liver damage. People who have liver disease shouldn't take methotrexate, and you shouldn't drink alcohol when taking it.
Methotrexate can be very harmful to a developing baby, so it's important that women use contraception and don't become pregnant while they take this drug and for 3 months after they stop. Methotrexate can also affect the development of sperm cells, so men shouldn't father a child during treatment and for 3 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's 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 the production of skin cells. It's used to treat severe psoriasis that hasn't responded to other non-biological systemic treatments. It's 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's important that women use contraception and don't become pregnant while they take this drug, and for 2 years after they stop taking it. However, it's 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 hasn't responded to other treatments, or if you can't use other treatments.
Etanercept is injected twice a week and you'll be shown how to do this. If there's 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's a risk of serious side effects, including severe infection. If you had tuberculosis in the past, there's a risk it may return. You'll be monitored for side effects during your treatment.
Adalimumab is injected once every 2 weeks and you'll be shown how to do this. If there's no improvement in your psoriasis after 16 weeks, the treatment will be stopped.
Adalimumab can be harmful to a developing baby, so it's important that women use contraception and don't become pregnant while they take this drug, and for 5 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's a risk of serious side effects, including severe infections. You'll be monitored for side effects during your treatment.
Infliximab is given as a drip (infusion) into your vein at the hospital. You'll have 3 infusions in the first 6 weeks, then 1 infusion every 8 weeks. If there's 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's a risk of serious side effects, including severe infections. You'll be monitored for side effects during your treatment.
Ustekinumab is injected at the beginning of treatment, then again 4 weeks later. After this, injections are every 12 weeks. If there's 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's a risk of serious side effects, including severe infections. You'll be monitored for side effects during your treatment.
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.
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 that it fits your lifestyle.
Keep up your treatment
It's 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.
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 than the general population, although it's not known why. Regular exercise and a healthy diet are recommended for everyone, not just people with psoriasis, because they can help to prevent many health problems.
Eating a healthy, balanced diet and exercising regularly can also relieve stress, which may improve your psoriasis.
Emotional impact of psoriasis
Because of the effect 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.
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 psoriasis, but about 20% develop it before they're diagnosed with psoriasis.
There's no single test for psoriatic arthritis. It's 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'll usually have an annual assessment to look for signs of psoriatic arthritis.
If your doctor thinks you have psoriatic arthritis, you'll usually be referred to a specialist called a rheumatologist, so you can be treated with anti-inflammatory or anti-rheumatic medicines.
Psoriasis doesn't 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're 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 them. Support groups can increase your self-confidence, reduce feelings of isolation, and give you practical advice about living with the condition.
Further information and support for psoriasis is available from the charity Changing Faces.
22 February 2023
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