Psoriasis This factsheet is for people who have psoriasis

Psoriasis
This factsheet is for people who have psoriasis, or who would like information about it.
Psoriasis is a common skin condition that causes patches of inflamed skin. It isn't contagious.

About psoriasis
Your skin constantly sheds old cells and replaces them with new ones from underneath, in a cycle that usually takes about 28 days. If you have psoriasis, the rate at which your skin is replaced in the affected area is increased and the cycle can be as quick as two to six days. New skin cells move too rapidly to the surface before they have properly matured and then accumulate on the surface of your skin. This forms thick patches called plaques. There is also a build-up of a type of white blood cell (called T-cells) under your skin, which causes inflammation.
Psoriasis affects around two in 100 people. Psoriasis can begin at any age, and affects similar numbers of men and women.
Most people with psoriasis have the condition for life. However, it tends to come and go - often for no apparent reason - and the severity of each flare-up can vary. Psoriasis isn't contagious so it can't be caught from other people, and it doesn't spread from one part of your body to another.
Types of psoriasis
There are a number of different types of psoriasis.
Plaque psoriasis
Plaque psoriasis is the most common type of psoriasis, where you get pinkish-red scaly plaques (patches), especially on your knees and elbows.
Flexural psoriasis
Flexural psoriasis is most common in older people. It affects areas where your skin is folded - such as your armpits and groin area, where your skin tends to be thinner and more sensitive than in other areas of your body. Flexural psoriasis is also known as inverse psoriasis. Rather than the typical plaques seen with other types of psoriasis, flexural psoriasis causes patches of bright red, shiny skin. They may be very uncomfortable and painful. You may have flexural psoriasis at the same time as having plaques elsewhere on your body.
Pustular psoriasis
This is a rare, severe form of the condition, in which small pus-filled spots (pustules) develop on your skin. If this happens all over your body, it's called generalised pustular psoriasis - or von Zumbusch pustular psoriasis. This can be a very serious life-threatening condition and you may need to be treated in hospital.
Erythrodermic psoriasis
Erythrodermic psoriasis is another rare and severe form of the condition, in which your skin becomes red and inflamed all over. This intense inflammation results in protein and fluid loss, which can lead to a serious illness. It usually needs to be treated in hospital. Erythrodermic psoriasis usually only develops in people who already have another type of psoriasis.
Guttate psoriasis
In this form of psoriasis, small, circular, inflamed patches of skin suddenly appear all over your body, usually after a throat infection. It tends to affect children and young adults.

Symptoms of psoriasis
Psoriasis occurs in different forms, but you will usually have thickened and red patches of skin. Your skin may feel itchy, and can sometimes feel painful or sore. If you have only very mild symptoms, you may not be aware you have it.
Some types of psoriasis can affect your scalp and cause redness and flaking. It can also affect your fingernails, which can become pitted, thickened or loosened from the nail bed.
If you have any of these symptoms, contact your GP.

Complications of psoriasis
About one in four people with psoriasis also develop joint disease. Usually the joints at the end of your fingers and toes are affected, although your back, knees and hips may be affected too.

Causes of psoriasis
If you have psoriasis, substances produced by your immune system cause your skin to start producing new cells faster than usual. This causes your skin to thicken and become scaly. What makes your immune system act like this isn't clear.
You're more likely to get psoriasis if you have a family history of the condition. However, if your parents have psoriasis, you won't necessarily get it. A trigger is needed for you to develop psoriasis and environmental factors may play a role. The trigger could be a throat infection, an injury to your skin, the effects of certain medicines, physical or emotional stress or even smoking or drinking alcohol. For many people, there is no obvious cause.

Diagnosis of psoriasis
Your doctor will ask about your symptoms and examine you. He or she may also ask you about your medical history.
Your GP will probably be able to diagnose psoriasis from your symptoms and a physical examination. However, if your psoriasis is extensive or severe, if it's affecting your education or work, if it's not responding to treatment, or if your diagnosis is uncertain, your GP may refer you to a dermatologist (a doctor who specialises in identifying and treating skin conditions).
If you have generalised pustular psoriasis or erythrodermic psoriasis, you may need to be admitted to hospital for treatment.

Treatment of psoriasis
There is no cure for psoriasis. However, there are a number of treatments that can help relieve your symptoms.
Self-help
Your GP will probably advise you to use emollients - creams or lotions that moisten, soften and soothe your skin. He or she will usually prescribe these, but you can also buy them from a shop without a prescription. Always read the patient information leaflet that comes with your medicine. Ask your GP for advice on how to get the best results.
Medicines
Topical treatments
Your GP may prescribe you a medicated cream or ointment. The type and strength of topical treatment will depend on the type of psoriasis you have. Common types of preparations include those containing:
coal tar - these preparations can reduce inflammation and scaling, and are often used in psoriasis affecting your scalp; however, they can be smelly and messy
steroids - these preparations are often used for localised psoriasis (eg patches on your elbows or knees), but shouldn't be used if your psoriasis is quite widespread; stronger steroids can be used on your palms and soles, or your scalp
vitamin D derivatives (such as calcipotriol or tacalcitol) - these preparations can be easier to use than some of the other products, but sometimes irritate your skin
Always ask your doctor for advice and read the patient information leaflet that comes with your medicine.
Oral medicines
If topical treatments don't control your symptoms, or if your psoriasis is extensive, you may be prescribed medicines that you take as tablets, such as:
methotrexate
acitretin
ciclosporin
hydroxycarbamide
These medicines work by suppressing your immune system, or by slowing down the production of skin cells. They are prescribed by a dermatologist.
If you're a woman, you will be warned not to become pregnant while taking these medicines and, in some circumstances, for some time afterwards. With some of the tablets, men will also be advised that they shouldn't get their partner pregnant. This is because these medicines can cause serious damage to an unborn baby.
Biological agents are newer treatments for psoriasis that can be very effective, but tend to be restricted to people with severe psoriasis. They are given as an injection into your skin, or through a drip into a vein in your arm. These medicines include:
etanercept
adalimumab
infliximab
ustekinumab
Your dermatologist can discuss these treatments with you. You will need to have various pre-treatment tests before you can try these medicines, and you will be monitored with blood tests while you're receiving the treatment.
Always ask your doctor for advice and read the patient information leaflet that comes with your medicine.
Light therapy
If your psoriasis is widespread and covers a large part of your body, or if it doesn't respond to the treatments above, your dermatologist may recommend that you have light therapy.
The ultraviolet light is given in a machine that looks similar to a shower cubicle, containing fluorescent tubes.
Ultraviolet B (UVB) light therapy involves shining artificial UVB light on to your skin. You will usually have the therapy two to three times a week for up to 10 weeks. UVB light occurs naturally in sunlight.
Sometimes UVB light therapy is used in combination with topical treatments such as steroid creams or coal tar preparations. This combination may be effective at helping to control your symptoms by making your skin more sensitive to UVB light.
Psoralen and ultraviolet A (UVA) light treatment (also called PUVA) involves combining a medicine that sensitises your skin to sunlight (psoralen) with a controlled dose of UVA light. You may have psoralen as a tablet or applied directly to your skin. You usually have the treatment twice a week, for up to 10 weeks.