Psoriasis: Types, Triggers and Treatment

Psoriasis is a long-term condition in which the immune system speeds up the growth of skin cells. Instead of shedding over about a month, new cells build up in days, forming raised, scaly patches called plaques. Psoriasis is not contagious. It tends to come and go in flares, and although there is no cure, modern treatments can clear the skin for many people.

Key facts

Psoriasis affects about 2 to 3 people in every 100.
It can start at any age but most often begins in young adults.
On darker skin, plaques often look purple, grey or dark brown rather than red.
Up to 1 in 3 people with psoriasis develop joint pain from psoriatic arthritis.
It is linked to a higher risk of heart disease, diabetes and depression.

Types of psoriasis

Plaque psoriasis, the most common type, causes raised patches with silvery-white scale, often on the elbows, knees, scalp and lower back.
Scalp psoriasis causes thick scale on the scalp that may extend past the hairline and is often mistaken for dandruff.
Guttate psoriasis appears as many small drop-shaped spots, often after a strep throat infection, mainly in children and young adults.
Inverse psoriasis affects skin folds such as the armpits, groin and under the breasts, where it looks smooth rather than scaly.
Nail psoriasis causes pitting, discolouration and lifting of the nails.
Pustular and erythrodermic psoriasis are rare, severe forms that need urgent medical care.

Causes and triggers

Psoriasis runs in families and results from a mix of genes and immune system changes. Flares can be set off by:

Infections, especially throat infections
Skin injury, such as cuts, scratches or tattoos
Stress
Smoking and heavy alcohol use
Some medicines, including lithium, some antimalarials and beta-blockers
Cold, dry weather

Symptoms

Raised, well-defined patches with scale
Itching, burning or soreness
Dry, cracked skin that may bleed
Pitted or thickened nails
Stiff, swollen or painful joints if psoriatic arthritis develops

Diagnosis

A doctor can usually diagnose psoriasis by examining the skin, scalp and nails. Occasionally a small skin sample (biopsy) is taken to rule out other conditions such as eczema or fungal infection. Tell your doctor about any joint pain, as early treatment of psoriatic arthritis prevents joint damage.

Treatment

Treatment depends on how much skin is affected, where it is, and how much it affects your life.

Creams and ointments

Emollients (moisturisers) used daily soften scale and reduce itching.
Steroid creams reduce inflammation during flares.
Vitamin D analogues, such as calcipotriol, slow skin cell growth and are often combined with a steroid.
Coal tar and salicylic acid products help with scale, especially on the scalp.

Light therapy

Narrowband UVB phototherapy, given in hospital clinics, helps when psoriasis covers larger areas.

Tablets and injections

For moderate to severe psoriasis, a specialist may prescribe medicines that act on the whole body, such as methotrexate, ciclosporin or acitretin, or newer biological injections that target specific parts of the immune system. These need regular blood tests and monitoring.

A note on alternative therapies

Many herbal products, oils and supplements are promoted for psoriasis. There is little reliable evidence that they work, and some unlabelled creams contain strong steroids that can thin the skin or cause a severe flare when stopped. Check with a doctor or pharmacist before using them, and do not stop prescribed treatment in their place. Relaxation techniques and stress management may help some people cope with flares alongside medical treatment.

Living with psoriasis

Moisturise every day, even when the skin looks clear.
Stop smoking and cut down on alcohol, both of which make psoriasis worse.
Keep a healthy weight, which can improve response to treatment.
Get your blood pressure, cholesterol and blood sugar checked regularly, because psoriasis raises the risk of heart disease and diabetes.
Seek support if psoriasis affects your mood or confidence. Depression and anxiety are common and treatable.

When to see a doctor

See a doctor if you have a scaly rash that does not improve with moisturiser, if psoriasis is affecting your sleep, work or mood, or if you develop joint pain. Seek urgent care if your skin becomes red and inflamed all over, or you develop widespread pus-filled spots with fever, as these are signs of rare severe forms.

Frequently asked questions

Is psoriasis contagious?

No. It cannot be passed on by touch, sharing towels or any other contact.

Will psoriasis go away?

It is a long-term condition, but it often goes quiet for long periods, and treatment can clear the skin.

What is the difference between psoriasis and eczema?

Both cause itchy patches, but psoriasis plaques are usually thicker, more sharply defined and more scaly, and commonly appear on the elbows, knees and scalp.