Psoriasis

What is psoriasis?

Psoriasis is a common, long-term skin condition that causes patches of dry, flaky, itchy skin that can look like silvery-white scales. It happens because your immune system causes new skin cells to be made much faster than usual, so they build up on the surface of your skin instead of shedding normally.

What are the symptoms of psoriasis?

The main symptom is dry, itchy, sore, flaky patches of skin, which can look silvery-white. On white skin, patches are usually pink or red, sometimes turning a waxy yellow or orange-brown colour. On brown or black skin, patches tend to look grey, and can leave dark marks once the psoriasis has gone.

• Patches can be variable in size (they can be larger than 2cm), with an oval or irregular shape
• Small brown and yellow spots on the palms of your hands and soles of your feet
• Nails with dents or pits in them
• Itching or soreness.

Psoriasis most commonly affects your scalp, chest, tummy, back, bottom, forearms, elbows, lower legs and knees, though it can appear anywhere, including skin folds such as your groin. Symptoms tend to come and go in flare-ups, with better periods in between.

What are the causes of psoriasis and who is at risk?

Psoriasis happens because your skin makes new skin cells much faster than normal, causing patches to build up on the surface. Doctors think this is caused by a problem with your immune system, though it isn't fully understood why or how this happens. You're more likely to have psoriasis if a member of your family has it.

Certain things can trigger a flare-up or make your psoriasis worse, including:

• stress
• drinking alcohol or smoking
• being overweight
• pregnancy
• certain medicines
• infections, such as strep throat and HIV
• cuts, scratches or grazes on your skin
• sunburn, or cold, dry weather.

Psoriasis is not contagious, so you cannot catch it from someone else or pass it on.

Are there different types of psoriasis?

There are several types of psoriasis. You can have more than one type at once, or one type can change into another.

• Plaque psoriasis: The most common type, causing raised, red patches covered in silvery-white scales, usually on the scalp, trunk and limbs
• Guttate psoriasis: Small, red, drop-shaped spots, often in children or young adults, and often triggered by a throat infection such as strep throat
• Pustular psoriasis: Small, pus-filled bumps surrounded by red skin, usually on the hands and feet
• Inverse psoriasis: Smooth, red patches in skin folds, such as under the breasts, groin or armpits, made worse by rubbing and sweating
• Erythrodermic psoriasis: A rare, severe form that causes redness and shedding of skin over most of the body, and needs urgent medical attention
• Nail psoriasis: Pitting, dents and discolouration of your fingernails or toenails.

How is psoriasis diagnosed?

A doctor can usually diagnose psoriasis by examining your skin and asking about your symptoms and family history. Occasionally, they may take a small sample of skin (a biopsy) to rule out other conditions, such as eczema.

They may also use scoring tools to assess how severe your psoriasis is and how much it's affecting your life, based on how much of your body is affected and the thickness, scaling and redness of your skin.

How is psoriasis treated?

Non-surgical treatment

Most people are treated with topical treatments applied directly to the skin, especially for mild to moderate psoriasis. These include:

• Vitamin D creams, lotions, ointments or gels
• Moisturising treatments (emollients), to soothe and protect your skin
• Steroid creams or ointments
• Other treatments such as coal tar preparations, particularly for your scalp.
• It may take up to six weeks to see a noticeable effect, and you may need a combination of different treatments. A GP can prescribe many of these, or refer you to a skin specialist (dermatologist) if needed.

Further treatment for more severe psoriasis

If your psoriasis is more severe, doesn't respond to creams, or affects a large area of your body, further options include:

• Light therapy (phototherapy), where your skin is regularly exposed to certain wavelengths of light under medical supervision
• Tablets or injections that work throughout your body, including medicines that calm the immune system, such as methotrexate or ciclosporin, and newer biologic treatments

When should I see a doctor?

See a GP if you have symptoms of psoriasis, if your treatment isn't working or is causing side effects, or if you have psoriasis alongside joint pain, stiffness or swelling that keeps coming back, as this can be a sign of psoriatic arthritis.

Call 999 or go to A&E if you have psoriasis and:

• Your skin quickly turns red and develops white, pus-filled bumps that join together (redness can be harder to see on brown or black skin)
• You have psoriasis patches on your feet that turn yellow-brown and fill with pus
• Your fingers and toes develop red, scaly, pus-filled bumps on the tips.

These can be signs of a rare but serious complication or infection, especially alongside a fast heartbeat, high temperature, or feeling hot, cold or shivery.