Psoriasis

What is psoriasis?

Psoriasis is a common, long-term inflammatory condition that comes and goes throughout life. It is caused by overactivity of the immune system, which leads to inflammation in the skin and makes skin cells grow and build up much faster than normal. This creates raised, scaly patches called plaques.

Psoriasis is one of a group of immune-mediated inflammatory diseases, which also includes psoriatic arthritis, ankylosing spondylitis and inflammatory bowel disease. It is not just a skin condition and can affect general health.

Who gets it?

Around 2 in 100 people have psoriasis. It can start at any age, but it most often begins either in the late teens and early twenties or between the ages of 50 and 60. It affects men and women equally.

What causes it?

Its precise cause is not known, though genes and environment both contribute. Something triggers the immune system to become more active, leading to long-lasting inflammation.

Recognised triggers include infections, particularly streptococcal throat infections; skin injury, where psoriasis can appear in a scratch, cut or scar; certain medicines, such as lithium, beta-blockers used for blood pressure and heart conditions, anti-malarial medicines, and stopping oral steroids suddenly; stress; alcohol; smoking; and being overweight. Sunlight improves psoriasis in many people but can make it worse in a few. Pregnancy often improves psoriasis but not always.

Is it hereditary or contagious?

Psoriasis often runs in families: roughly one in three people with it has a close relative who is also affected. The way it is inherited is complex.

Psoriasis is not contagious and cannot be caught from someone else.

What does it look and feel like?

Psoriasis typically causes well-defined, raised plaques with a silvery-white scale. On lighter skin they look pink or red. In brown and black skin, plaques can appear purple, grey or dark brown, and may leave darker or paler marks once they fade. Psoriasis does not usually scar.

It is often itchy, and can be sore or painful, particularly on the scalp, lower legs and in the groin. On the hands and feet, painful cracks can develop that affect the use of the hands and walking. Scale shedding onto clothing can be distressing.

Commonly affected areas are the elbows, knees, scalp, behind the ears, the lower back, the navel and between the buttocks, but any area can be involved. Psoriasis on the face, scalp, hands, feet, nails and genitals can have a particularly large effect on quality of life.

Types of psoriasis

The commonest form is chronic plaque psoriasis, which produces plaques on the elbows, knees, scalp and trunk.

Guttate psoriasis causes many small, drop-shaped patches scattered over the trunk and limbs, often appearing suddenly after a throat infection, particularly in young people.

Flexural (inverse) psoriasis affects skin folds such as the armpits, groin, genitals and under the breasts. It is smooth and shiny rather than scaly.

Palmoplantar psoriasis affects the palms and soles, and can include palmoplantar pustulosis, where yellow pus spots appear on the hands and feet.

Pustular psoriasis and erythrodermic psoriasis are rare, severe forms that can affect large areas of skin and may need urgent hospital care.

Nails and joints

About half of people with psoriasis have nail changes. These include small pits, ridges, salmon-pink or yellow discolouration, lifting of the nail from the nail bed, and thickening or crumbling.

About 1 in 5 people with psoriasis develop psoriatic arthritis. This causes pain, swelling and stiffness in the joints, often worse in the morning or after rest, and can also cause swelling of a whole finger or toe, heel pain or lower back stiffness. Psoriatic arthritis can cause permanent joint damage if not recognised, so it is important to mention any joint symptoms. Nail psoriasis is associated with a higher risk of psoriatic arthritis.

Effects on general health

People with psoriasis, particularly more severe psoriasis, have a higher risk of other health problems, including heart disease, stroke, high blood pressure, raised cholesterol, diabetes, obesity, fatty liver disease, and anxiety and depression. Psoriasis can also have a considerable effect on confidence, relationships and work. Looking after general health is an important part of managing psoriasis.

How is it diagnosed?

Psoriasis is usually diagnosed from the appearance and distribution of the skin changes. A skin biopsy is occasionally needed if the diagnosis is uncertain. Your dermatologist may also ask about joint symptoms, use questionnaires to measure how much psoriasis affects your life, and recommend checks for related health conditions.

What are the treatment options?

Dr Mounsey has a special interest in psoriasis and its advanced treatment. He will assess the type and extent of your psoriasis, its effect on your quality of life, and check for joint symptoms and related health issues. Treatment options include vitamin D creams, often combined with topical steroids, scalp treatments, and coal tar or salicylic acid preparations. Phototherapy may be recommended for more widespread psoriasis. Tablets such as methotrexate, ciclosporin, acitretin or apremilast are options when creams are not enough, and biologic injections are highly effective for moderate to severe psoriasis. Dr Mounsey will explain the options and arrange the necessary blood tests and monitoring.

What is the outlook?

There is no cure for psoriasis, but there are many effective treatments, and most people can achieve good, long-term control. Psoriasis sometimes clears on its own for a period of time.

More information

British Association of Dermatologists patient leaflet: https://www.bad.org.uk/pils/psoriasis-an-overview

This page gives general information only and is not a substitute for a consultation. Everyone's skin is different, and what is right for you will depend on your own circumstances. If you are worried about a skin problem, please book an appointment with Dr Mounsey or speak to your GP. If you have a mole or skin lesion that is changing, bleeding or growing quickly, please seek medical advice promptly.