Psoriasis

The exact reasons why you may develop psoriasis aren't fully understood at present. It appears that your genes are the most important factor in causing the condition because you're more likely to get psoriasis if other people in your family have it. However, this doesn't mean you will definitely get the condition.

Environmental factors also play an important role in triggering psoriasis. These include a bacterial throat infection, the effects of certain medicines or stress. For many people, there is no obvious cause.

The genetic and environmental triggers lead to immune cells in your skin setting off inflammation. This causes your skin to start producing new cells faster than usual, leading to psoriatic plaques. What makes your immune system act like this isn't clear.

Psoriasis occurs in different forms, but you will usually have thickened, red patches of skin, which may have silver/white scales. The patches can vary in size and are clearly defined from the surrounding skin. Your skin may feel itchy, painful or sore. If you have mild symptoms, you may not be aware that you have psoriasis.

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, see a doctor.

Your doctor will ask about your symptoms and examine you. He or she will probably be able to diagnose psoriasis from your symptoms and by looking at your skin and nails. Your doctor may refer you to a dermatologist (a doctor who specialises in identifying and treating skin conditions) if a definite diagnosis can't be made or if your psoriasis is:

• extensive or severe
• affecting your education or work
• not responding to treatment

If you have generalised pustular psoriasis or erythrodermic psoriasis, you may need to go to hospital for urgent treatment.

Although there is no cure for psoriasis, there are a number of treatments that can help relieve your symptoms. Treatments vary in how effective they are for different people and you may need to try several before you find one that works for you.

Self-help

Your doctor may advise you to use emollients – creams or lotions that moisten, soften and soothe your skin. Having a warm bath may help to soften your psoriasis – your doctor may suggest adding bath oil.

Medicines

Topical treatments

These are treatments that you apply to your skin. Your doctor may prescribe you a medicated cream or ointment – the type and strength will depend on your psoriasis, but common treatments include the following.

• Coal tar preparations can reduce inflammation and scaling, and are often used to treat psoriasis affecting your scalp. However, they can be smelly and messy.
• Creams that contain dithranol can be very effective, but they are messy and can irritate healthy skin, so they aren't often prescribed.
• Steroid preparations are often used for localised psoriasis (for example, on your elbows or knees). You may be able to use stronger steroids on your palms and soles, or your scalp. Generally, steroid creams are only used short-term.
• Vitamin D derivatives (such as calcipotriol or tacalcitol) can be easier to use than some of the other products, but may irritate your skin.
• Vitamin A derivatives (retinoids) can be useful, but they are prone to causing skin irritation.

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 can have severe side-effects and need to be prescribed by a doctor.

Women 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 medicines are newer treatments for psoriasis that can be very effective, but tend to be restricted to people with severe psoriasis, or if other treatments haven't worked. 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 doctor 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.

Availability and use of medicines may vary from country to country.

Light therapy

Depending on the type and extent of your psoriasis, your doctor may recommend that you have ultraviolet (UV) light therapy.

You have the light therapy 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. UVB light occurs naturally in sunlight. You will usually have the therapy two to three times a week for up to eight weeks.
• Sometimes UVB light therapy is used in combination with topical treatments such as 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 UVA light therapy (PUVA) involves combining a medicine (psoralen) that sensitises your skin to sunlight 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.