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Psoriasis
Published by BUPA's health information team, healthinfo@bupa.com, March 2007.
This factsheet is for people who have psoriasis or who know someone who does.
Psoriasis is a chronic (prolonged) inflammation of the skin. Often there are red patches (plaques) on the skin covered by silvery scales of dead skin. The condition is not infectious and is not usually severe enough to affect general health.
Who gets psoriasis?
Psoriasis is quite common, affecting around two percent of the UK population, although people with very mild symptoms may not be aware they have it. Psoriasis can begin at any age, but it most commonly starts between the ages of 11 and 45. It often starts in the late 20s.
The underlying cause of psoriasis isn't known, but it tends to run in families. If both of your parents are affected, you have a 60 percent chance of developing the condition.
Environmental triggers are important too, stimulating the development of the condition if you are susceptible to it. Triggers include throat infections, skin trauma such as cuts, bruises or burns, some medicines, stress or psychological trauma, smoking and high alcohol intake. And although psoriasis is much more likely if you have a family history of the condition, others may still get it.
Symptoms of psoriasis
Psoriasis occurs in different forms, but it usually involves the thickening and reddening of patches of skin. Patches of psoriasis typically occur on the elbows, knees, scalp and lower back, but it can sometimes affect the whole body. These patches have a thick silvery-white scale of dead skin on the top, and may be itchy (see The main types of psoriasis).
Most people with psoriasis have the condition for life. However, it tends to comes and go, often for no apparent reason, and the severity of each flare-up can vary.
The main types of psoriasis
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Plaque psoriasis. Scaly patches (plaques) on the elbows, knees, lower back and scalp. The plaques, which are sometimes itchy, may be as small as 1cm in diameter, or more than 10cm. This is the most common form of psoriasis.
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Inverse or flexural psoriasis. Red, shiny patches in skin folds in the armpits and groin, and under the breasts for women. These usually have no scaling.
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Pustular psoriasis. Yellow round pustules appear on the palms of the hands and the soles of the feet. They gradually turn brown and are shed as scales reach the surface. Sometimes, and more seriously, they cover other parts of the body too. If this happens you may need to be admitted to hospital.
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Erythrodermic psoriasis. Inflammation of all of the skin, which becomes hot, red and dry. This is a very rare but serious condition which may also require admission to hospital.
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Guttate psoriasis. Lots of small, drop-shaped scaly patches, usually less than 1cm in diameter, mostly on the trunk, but also elsewhere. This type of psoriasis may start suddenly, after a throat infection, and is most often seen in children and young adults.
Psoriasis can also occur on the scalp (scalp psoriasis), where it can cause redness and flaking, or smooth patches may appear on the soles of the feet and palms of the hands. Fingernails can also be affected by pitting like on a thimble, discolouration or breakage.
Around 10 percent of people with psoriasis also have associated arthritis (inflamed joints) called psoriatic arthritis. This can range from being very mild to severe. Usually the joints at the end of the fingers and toes are affected, although the back, knees and hips may be too. For more information, please see the separate health BUPA factsheet Psoriatic arthritis.
Causes of psoriasis skin changes
In areas affected by psoriasis, there seems to be a rapid increase in the speed at which skin cells are replaced. Skin usually takes about 28 days to replace itself, but in areas affected by psoriasis it only takes three or four days. New skin cells move rapidly to the surface before they are properly mature, forming the thick psoriatic patches. There is also a build up of a particular kind of white blood cell (called T-cells) under the skin, which causes inflammation.
It's thought that substances produced by the immune system may cause both the build up of T-cells and the abnormal turnover of skin cells - but what makes the immune system act like this isn't clear.
Diagnosis of psoriasis
Your doctor can usually diagnose psoriasis from the symptoms you describe and a physical examination. In some cases, a small skin sample may be taken to be tested in a laboratory (biopsy) to help confirm the diagnosis.
Treatment of psoriasis
Self-care action plan
There are several common-sense ways to help minimise psoriasis flare-ups.
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Where possible, avoid anything known to trigger the condition.
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Do not scratch or pick at the skin: it may bleed and become infected, and psoriasis may then develop in that area.
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Avoid soap, which can be drying, and instead wash with aqueous cream or an emollient wash (eg E45).
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After washing, pat the skin dry, don't irritate it by rubbing vigorously.
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Use plenty of moisturising cream to soothe and soften the skin. This is especially effective after washing.
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Sunlight helps some people with psoriasis. However, avoid the sun if it causes pain and avoid getting burnt.
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Wear cotton clothes next to the skin and avoid rough, synthetic materials.
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Try to avoid alcohol and smoking.
Medicines and light treatments
There are many treatments available for psoriasis. Psoriasis creams and ointments are usually the first tried, followed by tablets and treatment with ultraviolet light. Some of the main treatments are listed below.
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Steroid creams. These can reduce inflammation and plaques. However, the creams may thin the skin, and the symptoms may return and increase when the treatment is stopped.
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Tar compounds - which are especially useful for scalp psoriasis. They are helpful for most people, but messy to use.
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Ointments containing vitamin D derivatives - recently developed for treating moderate psoriasis. However their effect may not last long and it may cause irritation on sensitive areas of skin.
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Vitamin A derivatives, which are available in tablet form and as ointment/cream (eg tazarotene). They aren't suitable for women who are, or who may become, pregnant.
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Light therapy. Evidence suggests that shining ultraviolet B on the affected area may help. It is available at specialist hospital clinics. Most experts advise against using home sunbeds because of the risk of burning, and because some produce pure ultraviolet A, which is not as effective at controlling psoriasis.
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Psoralen and ultraviolet A light treatment (also called PUVA). This involves combining a medicine which sensitises the skin to sunlight (psoralen) with a controlled dose of ultraviolet A light. It can reduce your symptoms if you have moderate psoriasis.
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Medicines that suppress the immune system are sometimes used if the psoriasis is severe - eg methotrexate and cyclosporin, which are taken as tablets. Newer drugs such as infliximab and efalizumab, which are injected, are also used in severe cases if other treatments haven't helped.
Complementary therapy
It is unusual for conventional medicine to cure psoriasis, or to relieve the symptoms completely. For this reason, many people turn to complementary therapies such as homeopathy, acupuncture and herbal remedies. Whether they are of any benefit is unclear, partly because people often use steroid creams at the same time as the complementary therapies, and also because of the way psoriasis naturally comes and goes.
Relaxation methods such as meditation, yoga and the Alexander Technique may well be beneficial because they reduce stress, a trigger for psoriasis.
Physiotherapy
If you have psoriatic arthritis, physiotherapy, certain exercises, and occupational therapy - where you learn to carry out daily tasks as easily as possible - can be helpful.
What is the outlook?
Psoriasis is a long-term condition and for many people is usually mild. It can however, have a profound social and psychological impact on daily living. There is currently no cure, but the range of treatments available is usually effective at relieving symptoms when they occur.
However, you should look out for possible complications such as infections (shown by skin becoming more painful, swollen, red or tender than usual) or arthritis and, if worried, see your GP.
Further information
Sources
- Chantal Simon, H.E., Jon Birtwistlke, Brian Stevenson, Oxford handbook of general practice. Diabetes. 2004: Oxford University Press. p. 456
- Psoriasis. National Psoriasis Foundation. www.psoriasis.org, accessed 4 December 2006
- Psoriasis - Interventions. BMJ Clinical evidence. www.clinicalevidence.com, accessed 4 December 2006
Reviewed by Dr James Quekett, Bsc.MB Ch.B MRCGP DRCOG DFFP, partner/principal general practitioner at Rowcroft Medical Centre.
Publication date: March 2007. Expected review date: March 2009.
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