Overview
Psoriasis is a skin condition that causes flaky, crusty patches of skin covered with silvery scales.
On brown, black and white skin the patches can look pink or red, and the scales white or silvery. On brown and black skin the patches can also look purple or dark brown, and the scales may look grey.
These patches normally appear on your elbows, knees, scalp and lower back but can appear anywhere on your body.
Most people are affected only in small patches. In some cases, the patches can be itchy or sore.
Psoriasis affects around 2 in 100 people in the UK. It can start at any age, but most often develops in adults between 20 and 30 years old and between 50 and 60 years old. It affects men and women equally.
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 (chronic) disease that usually involves periods when you have no symptoms or mild symptoms, followed by periods when the symptoms are more severe.
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 takes about 3 to 7 days.
The resulting build-up of skin cells is what creates the patches associated with psoriasis.
Although the process is not 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 it attacks healthy skin cells by mistake in people with psoriasis.
Psoriasis can run in families, although the exact role genetics play 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.
How psoriasis is diagnosed
A GP can often diagnose psoriasis based on the appearance of your skin.
You may be referred to a specialist in diagnosing and treating skin conditions (dermatologist) if your doctor is uncertain about your diagnosis, or if your condition is severe.
In rare cases, a small sample of skin called a biopsy will be sent to the laboratory for examination under a microscope.
If your doctor suspects you have psoriatic arthritis, which is sometimes a complication of psoriasis, you may be referred to a doctor who specialises in arthritis (rheumatologist).
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's no cure for psoriasis, but a range of treatments can improve symptoms and the appearance of skin patches.
Your doctor will ask you about how much the condition is affecting your everyday life.
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 not 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.
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 a GP or your 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.
Further information:
Symptoms
Psoriasis typically causes patches of skin that are dry and covered in scales.
On brown, black and white skin the patches can look pink or red, and the scales white or silvery. On brown and black skin the patches can also look purple or dark brown, and the scales may look grey.
Some people find their psoriasis causes itching or soreness.
There are several different types of psoriasis. Many people have only 1 type at a time, although you can have 2 different types together. One type may change into another 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 a GP if you think you may have psoriasis.
Common types of psoriasis
Plaque psoriasis
Plaque psoriasis is the most common form of psoriasis.
Its symptoms are dry red skin lesions, known as plaques, 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 or sore, or both. In severe cases, the skin around your joints may crack and bleed.
Scalp psoriasis
Scalp psoriasis is a type of plaque psoriasis. It can occur on parts of your scalp or on the whole scalp. It causes patches of skin covered in thick 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.
Nails can often become loose and separate from the nail bed. In severe cases, nails may crumble.
Guttate psoriasis
Guttate psoriasis causes small (less than 1cm) drop-shaped sores on your chest, arms, legs and scalp.
There's a good chance 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 these areas.
Inverse psoriasis is made worse by friction and sweating, so it can be particularly uncomfortable in hot weather.
Less common types of psoriasis
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
Generalised pustular psoriasis is a rare and serious form of psoriasis that usually needs emergency treatment. It causes pustules that develop very quickly on a wide area of skin. 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 pustulosis
This causes pustules to appear on the palms of your hands and the soles of your feet.
The pustules gradually develop into circular, scaly spots that then peel off.
Pustules may reappear every few days or weeks.
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 come on suddenly and may need emergency medical treatment.
It can cause your body to lose proteins and fluid. This can lead to serious illnesses such as infection, dehydration, heart failure, hypothermia and malnutrition.
Further information
Who can get it
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, where they die and flake off. This whole process normally takes around 3 to 4 weeks.
However, in people with psoriasis, this process only takes about 3 to 7 days. As a result, cells that are not fully mature build up rapidly on the surface of the skin, causing flaky, crusty patches covered with 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.
Genetics
Psoriasis runs in families, so you may be more likely to get psoriasis if you have a close relative with the condition, but the exact role genetics plays in psoriasis is unclear.
Research has shown that many different genes are linked to the development of psoriasis, and it's likely that different combinations of genes may make people more vulnerable to the condition.
However, having these genes does not necessarily mean you'll develop psoriasis.
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 psoriasis triggers include:
- an injury to your skin such as a cut, scrape, insect bite or sunburn - this is called the Koebner response
- drinking excessive amounts of alcohol
- smoking
- stress
- 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, and ACE inhibitors (used to treat high blood pressure)
- throat infections - in some people, usually children and young adults, a form of psoriasis called guttate psoriasis develops after a streptococcal throat infection, but 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 is not contagious, so it cannot be spread from person to person.
Treatment
Treatment for psoriasis usually helps to keep the condition under control. Most people can be treated by their GP.
If your symptoms are particularly severe or not responding well to treatment, your GP may refer you to a skin specialist (dermatologist).
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 is available for psoriasis, but identifying the most effective one can be difficult. Talk to your doctor if you feel a treatment is not working or you have uncomfortable side effects.
Treatments fall into 3categories:
- topical: creams and ointments 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
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.
Further information
Topical treatments
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
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 moisturise the skin and reduce itching and scaling. Some other topical treatments are thought to work better on moisturised skin. Wait at least 30 minutes before applying another 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.
Read more about emollients
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 them 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 do not use more than the recommended amount.
Calcineurin inhibitors
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 face, the genitals and folds in the skin, if steroid creams are not 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
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 are not effective.
Coal tar can stain clothes and bedding, and has a strong smell. It can be used in combination with phototherapy.
Dithranol
Dithranol has been used for more than 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 it's too concentrated.
It's typically used as a short-term treatment, under hospital supervision, for psoriasis affecting the limbs or trunk, as it stains everything it comes into contact with, including skin, clothes and bathroom fittings.
It's applied to your skin (by someone wearing gloves) and left for 10 to 60 minutes before being washed off.
Dithranol can be used in combination with phototherapy.
Further information
Phototherapy
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
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 have not 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 UVB 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 is not encouraged, as it can increase your risk of developing skin cancer.
Combination light therapy
You may be offered creams or ointments (topical treatments) alongside light therapy if:
- your psoriasis is not responding to light therapy alone
- you cannot, or do not want to, take medicines for your psoriasis
Further information
Tablets, capsules and injections
If your psoriasis is severe or other treatments have not worked, you may be prescribed systemic treatments by a specialist. Systemic treatments 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.
If you're planning for a baby, become pregnant or are thinking of breastfeeding, you should also speak to your doctor first before taking any new medicine to check it's suitable for use during pregnancy or breastfeeding.
There are 2 main types of systemic treatment, called non-biological (usually given as tablets or capsules) and biological (usually given as injections).
Non-biological medications
Methotrexate
Methotrexate can help 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 should not take methotrexate, and you should not drink alcohol when taking it.
Methotrexate can be very harmful to a developing baby, so it's important that women use contraception and do not become pregnant while they take this drug and for at least 6 months after they stop.
Men are advised to delay trying for a baby until at least 6 months since their last dose of methotrexate.
Ciclosporin
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
Acitretin is an oral retinoid that reduces skin cell production . It's used to treat severe psoriasis that has not 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 do not become pregnant while taking this drug, and for at least 3 years after they stop taking it. However, it's safe for a man taking acitretin to father a baby.
Newer drugs
Apremilast and dimethyl fumarate are newer medicines that help to reduce inflammation. They are taken as daily tablets. These medicines are only recommended for use if you have severe psoriasis that has not responded to other non-biological treatments.
Further information
Biological treatments
Biological treatments reduce inflammation by targeting overactive cells in the immune system. They are usually used if you have severe psoriasis that has not responded to other treatments, or if you cannot use other treatments.
Etanercept
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 have had tuberculosis in the past, there's a risk it may return.
You'll be monitored for side effects during your treatment.
Adalimumab
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.
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
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
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.
Other drugs
There is an increasing number of biological treatments that are given as injections. These include guselkumab, brodalumab, secukinumab, ixekizumab, and bimekizumab.
They're recommended for people who have severe psoriasis that has not improved with other treatments or when other treatments are not suitable.
Further information