Psoriasis

Overview

Psoriasis is a long-lasting inflammatory skin condition that tends to come and go. The NHS says the exact cause is unknown, but a problem with the immune system, together with genes and environmental triggers, appears to play a role. Reviews link the skin patches to skin cells multiplying faster than usual. The NHS says psoriasis cannot be cured, but treatments can manage the symptoms.

Symptoms

What a clinician may find

• Raised red patches covered with silvery scales
• Plaques that commonly appear on the scalp, knees and elbows
• Nail changes such as pitting, ridging, discolouration or abnormal growth

Complications

• Psoriatic arthritis, a joint condition that some people with psoriasis develop
• Metabolic syndrome and inflammatory bowel disease, particularly Crohn's disease, which NICE clinical knowledge summaries say may be associated with psoriasis
• Anxiety and depression

Diagnosis

Diagnosis is usually clinical, which means the GP examines the skin to check for psoriasis. An NHS source says a biopsy is sometimes needed to help find the exact cause of symptoms. NICE guidance advises referral to dermatology when the diagnosis is uncertain at first presentation, or when psoriasis cannot be controlled with topical treatment. A dermatologist is a specialist skin doctor.

Treatment

Treatment is stepped. The NHS says mild psoriasis can be treated with creams and ointments, and that an emollient is probably the first treatment a GP will suggest. If these do not work, the NHS says light treatment (phototherapy) or stronger medicines may be needed. NICE guidance describes phototherapy with ultraviolet B light as second-line therapy. Stronger options include tablets and injections that work throughout the body, such as ciclosporin, methotrexate and acitretin, and injected biological medicines.

Prevention

The NHS says the exact cause of psoriasis is unknown. NHS 111 Wales lists stress, drinking alcohol, smoking, obesity, certain medicines and infections as possible triggers. The British Association of Dermatologists says how these factors lead to psoriasis is not fully understood.

Key facts

What does psoriasis look like?

Psoriasis is described in medical reviews as a long-lasting, recurring inflammatory skin condition. Its typical appearance is raised red patches covered with silver scales. The British Association of Dermatologists lists the scalp, knees and elbows among the usual sites for these plaques, and says the scalp can be particularly itchy.

The nails can be affected too. A patient leaflet that credits the Psoriasis Association says nail involvement can include pitting, ridging of the nail surface and, at its most severe, complete nail destruction. The British Association of Dermatologists says nail psoriasis is present in about half of people with psoriasis, and that a small number of people have nail involvement only.

NHS information describes a rarer form on the feet, where pus-filled spots gradually develop into circular brown, scaly spots that peel off. The NHS says pus-filled patches on the feet that turn yellow-brown can signal a more serious condition or infection, and advises calling 999 or going to A&E.

What are the types of psoriasis?

The Psoriasis Association lists plaque, scalp, guttate, pustular, inverse and nail psoriasis among the main types of psoriasis. It also describes erythrodermic psoriasis and psoriasis in sensitive areas. NICE clinical knowledge summaries say chronic plaque psoriasis is the most common form, affecting 80 to 90 percent of people with psoriasis.

NHS inform Scotland describes guttate psoriasis as a form that sometimes occurs after a streptococcal throat infection, and says it is more common among children and teenagers. The NHS also describes a rarer form on the feet in which pus-filled spots develop.

NICE guidance says people with generalised pustular psoriasis or erythroderma should be referred immediately for same-day specialist assessment and treatment. It also advises referral to dermatology when nail psoriasis has a big impact on using the hands or on appearance.

What causes psoriasis and what sets it off?

The NHS says the exact cause of psoriasis is unknown, but a problem with the immune system, together with genes and environmental triggers, appears to play a role. Medical reviews describe psoriasis as a T cell-mediated autoimmune disease, which means a type of immune cell is central to the skin changes. They link the skin patches to skin cells called keratinocytes multiplying faster than usual, with immune cells moving into the skin.

NHS 111 Wales lists stress, drinking alcohol or smoking, living with obesity, being pregnant, certain medicines and infections such as strep A among the possible triggers. The British Association of Dermatologists says the onset and severity of psoriasis have been linked to alcohol, being overweight, smoking and stress, and that these factors all appear to cause low-grade inflammation. It adds that not everyone who smokes or drinks develops psoriasis, and that how these triggers lead to the condition is not fully understood.

How is psoriasis diagnosed?

Diagnosis is usually clinical, which means the GP examines the skin to check for psoriasis. An NHS source says a biopsy is sometimes needed to help find the exact cause of symptoms. A dermatologist is a specialist skin doctor.

NICE guidance on psoriasis advises referral to dermatology when the diagnosis is uncertain at first presentation, when any type of psoriasis cannot be controlled with topical treatment, or when it has a major impact on a person's physical, psychological or social wellbeing. It says that as soon as psoriatic arthritis is suspected, the person should be referred to a rheumatologist, a specialist in joint conditions.

NHS Scotland's pathway says mild psoriasis is managed in primary care. For moderate psoriasis, it advises routine referral to a secondary care service if appropriate topical treatment has failed after four weeks.

How is psoriasis treated?

Treatment is stepped. The NHS says mild psoriasis can be treated with creams and ointments, and that an emollient is probably the first treatment a GP will suggest. Emollients are moisturising treatments that help ease itching and scaling. Sources describing NHS practice also mention vitamin D analogues such as calcipotriol and steroid creams for mild to moderate psoriasis.

If these do not work, the NHS says light treatment (phototherapy) or stronger medicines may be needed. NICE guidance describes phototherapy with ultraviolet B light as second-line therapy, and NHS sources say hospital visits are needed to receive it. Stronger medicines include tablets and injections that work throughout the whole body. The non-biological options are ciclosporin, methotrexate and acitretin, and biological medicines are given by injection.

NHS Scotland's pathway says apremilast or biological medicines are for people in whom phototherapy and first-line systemic medicines have failed.

Living with psoriasis and related conditions

The NHS says psoriasis often affects mental health, and that support from other people with psoriasis, at a local group or online, can help. If psoriasis is affecting emotional wellbeing, the NHS says a GP can arrange a referral to a mental health specialist. National charities such as Psoriasis UK offer information and support.

A Psoriasis Association article by a GP describes water and detergents such as shower gel and bubble bath as drying to the skin, and suggests lukewarm bath or shower water and plenty of emollient. Newcastle Hospitals dermatology guidance advises against putting fingers into an emollient tub, as this can introduce bacteria and cause infection.

NICE clinical knowledge summaries say psoriasis may be associated with psoriatic arthritis, metabolic syndrome, inflammatory bowel disease, anxiety and depression. The NHS says some psoriasis treatments can harm a developing baby, so treatment may need to change for people who are planning a baby or are pregnant.

Frequently asked questions