Psoriasis: Symptoms, Types, Causes and Triggers
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Psoriasis: Symptoms, Types, Causes and Triggers
What psoriasis is, what it looks like, the main types, what causes it and how it's treated in the UK.
Get urgent help first. Call 999 or go to A&E if your skin suddenly becomes red and inflamed over most of your body, or you have widespread pus-filled spots, especially with a fever, chills or feeling very unwell. These can be signs of erythrodermic or generalised pustular psoriasis, which are emergencies. See a GP soon if you have painful, swollen joints. Online treatment isn't suitable in these situations.
Key fact: psoriasis affects around 2 in 100 people in the UK. It isn't contagious, it tends to come and go, and although there's no cure, treatment can clear patches or keep them under control.
Adults only online, and not in pregnancy or breastfeeding. Access Doctor's online psoriasis service is for adults aged 18 and over, and can't supply treatment if you're pregnant or breastfeeding: your GP or midwife can help. Children with psoriasis should see their GP.
What is psoriasis?
Psoriasis is a long-term condition in which the immune system speeds up the turnover of skin cells. Skin normally renews itself over about 3 to 4 weeks; in psoriasis it happens in a few days, so cells build up on the surface as raised, scaly patches called plaques.
It affects around 2 in 100 people in the UK. It can start at any age, but most often first appears in early adulthood or between the ages of 50 and 60, and is uncommon in children. It tends to come and go: flare-ups are followed by spells when the skin is clearer. Psoriasis isn't contagious, so you can't catch it or pass it on by touch.
Autoimmune
The immune system wrongly targets the skin, causing inflammation and fast skin cell growth.
Runs in families
Up to half of people with psoriasis have a family member with it, but genes alone don't cause it.
Not contagious
It can't spread from person to person, in swimming pools or by sharing towels.
Long-term
There's no cure yet, but treatment can clear patches or keep them under control.
Symptoms and early signs
The typical sign is a well-defined, raised patch of skin covered with scale. Early psoriasis may start as a few small, slightly scaly spots that slowly join up.
- Raised plaques with clear edges, usually on the elbows, knees, lower back and scalp.
- Scale that is silvery-white on white skin, and may be grey or thicker on darker skin.
- Itching, soreness or burning: many people find psoriasis itchy, despite its reputation. See our guide to psoriasis itch.
- Dry, cracked skin that can bleed, especially over joints and on the hands and feet.
- Nail changes: tiny pits, discolouration or the nail lifting off. See nail psoriasis.
What psoriasis looks like on different skin tones
On white skin, plaques are usually pink or red with silvery scale. On brown and black skin they may look purple, dark brown or grey, and the redness can be harder to see, so psoriasis is sometimes missed or mistaken for eczema or a fungal rash. After a patch clears, the skin may stay darker or lighter for months. Our guide to psoriasis on black and brown skin covers this in detail.
Mild, moderate or severe?
Doctors judge severity by how much skin is affected and how much it affects your life. As a rough guide, the palm of your hand (including fingers) is about 1% of your skin. Psoriasis covering less than 3% is usually called mild; more than 10%, or any amount that badly affects your sleep, work or mood, is treated as severe.
Where psoriasis appears
| Area | What to expect | More information |
|---|---|---|
| Elbows, knees and lower back | The classic sites for plaque psoriasis: thick, well-defined, scaly patches. | Treatment options |
| Scalp and hairline | Thick scale that can look like severe dandruff, often spreading past the hairline and behind the ears. | Scalp psoriasis treatment |
| Face, ears and eyelids | Thinner, pinker patches; needs gentler treatment. | Face, ears and eyelids |
| Skin folds and genitals | Smooth, shiny red patches without much scale (inverse psoriasis). | Inverse psoriasis |
| Hands and feet | Thick, cracked skin on the palms and soles. | Hands and feet |
| Nails | Pitting, discolouration, thickening or lifting. | Nail psoriasis |
Types of psoriasis
- Plaque psoriasis (psoriasis vulgaris): by far the most common type. Raised, scaly plaques, usually on the elbows, knees, back and scalp.
- Scalp psoriasis: plaque psoriasis on the scalp. Around half of people with psoriasis have it.
- Guttate psoriasis: many small, drop-shaped spots across the chest, back, arms and legs, often 2 to 3 weeks after a strep throat infection. See guttate psoriasis.
- Inverse (flexural) psoriasis: smooth red patches in skin folds such as the armpits, groin and under the breasts.
- Nail psoriasis: affects around half of people with psoriasis, and more of those with psoriatic arthritis.
- Pustular psoriasis: pus-filled spots. Localised forms affect the palms and soles; generalised pustular psoriasis is an emergency.
- Erythrodermic psoriasis: rare. Red, inflamed skin over most of the body, often with chills and feeling unwell. It's an emergency.
Causes and triggers
Psoriasis develops when an inherited tendency meets something that switches the immune system on. Common triggers include a throat infection, a skin injury (new patches can form along a cut or scratch), stress, smoking, drinking alcohol, cold and dry weather, hormonal changes and some medicines, such as lithium, some beta-blockers and some antimalarials. Don't stop a prescribed medicine without speaking to your doctor.
Our psoriasis triggers guide explains each trigger and what you can do about it, and our guide to psoriasis and diet looks at what the evidence says about food and alcohol.
Joint problems and other linked conditions
Up to 1 in 3 people with psoriasis develop psoriatic arthritis, which causes painful, stiff and swollen joints, often in the fingers and toes. Spotting it early matters because treatment can prevent lasting joint damage. NICE advises checking for it at least once a year.
Psoriasis, especially when severe, is also linked with heart disease, type 2 diabetes, depression and anxiety. Our guide to psoriatic arthritis and linked conditions explains the warning signs.
How psoriasis is diagnosed
A GP can usually diagnose psoriasis by looking at your skin, scalp and nails and asking about your symptoms and family history. Tests are rarely needed, but a skin sample may be taken if the diagnosis isn't clear. Psoriasis can look like eczema, a fungal infection or other rashes; our guide to psoriasis vs eczema explains the differences.
How psoriasis is treated
Most psoriasis is treated with creams, ointments, gels or foams applied to the skin. In the UK, NICE recommends starting with a potent steroid and a vitamin D treatment such as calcipotriol, then adjusting if the skin doesn't clear. Emollients are used every day alongside. If treatments applied to the skin don't work, a dermatologist may offer light therapy, tablets or injections.
Our psoriasis treatment options guide sets out each step, and our guide to the best cream for psoriasis in the UK compares shop creams with prescription treatment.
When to see a GP: if you think you have psoriasis for the first time, if it covers a large area, if it's affecting your sleep, work or mood, if your joints are painful or swollen, or if treatment isn't working.
Living with psoriasis
Psoriasis can affect confidence, relationships and mental health, and that is as important to treat as the skin. Tell your GP if you feel low or anxious. Not smoking, drinking less alcohol and keeping to a healthy weight can all reduce flares and make treatment work better. The Psoriasis Association and the British Association of Dermatologists have reliable UK information and support.
Getting psoriasis treatment
If your psoriasis has already been diagnosed and you need treatment for patches on your body, arms or legs, our pharmacist prescribers can assess you online. See our psoriasis treatment page for the treatments we supply and who the service is suitable for. Scalp psoriasis has its own scalp psoriasis treatment page.
UK safety and reporting side effects
Prescription psoriasis treatments are only supplied after a GPhC-registered pharmacist independent prescriber reviews your consultation, including where your psoriasis is, how much skin it covers and what you have used before. Always read the patient information leaflet. Since 2024, UK steroid packs show their strength on the front (mild, moderate, strong or very strong). The MHRA advises using topical steroids for the shortest time needed, and to tell a healthcare professional if your skin flares badly after you stop a steroid you have used for a long time, which can be a topical steroid withdrawal reaction.
If you think you've had a side effect, tell your pharmacist or doctor. You can also report it to the MHRA through the Yellow Card scheme.
Frequently Asked Questions
Is psoriasis contagious?
No. Psoriasis is caused by the immune system, not an infection, so you can't catch it or pass it on by touch, sharing towels or swimming.
Can psoriasis be cured?
There's no cure yet, but treatment can clear patches completely or keep them under control for long periods. Many people have spells with little or no psoriasis.
Does psoriasis spread?
It doesn't spread to other people. On your own skin, new patches can appear during a flare or where the skin is injured, and small patches can join up, which is why treating flares early helps.
Is psoriasis genetic?
It often runs in families: up to half of people with psoriasis have a family member with it. Genes make it more likely, but a trigger such as an infection, stress or injury usually sets it off.
Can psoriasis go away on its own?
Patches sometimes clear without treatment, especially guttate psoriasis after a throat infection, which often fades within a few months. Plaque psoriasis usually comes and goes over many years.
What is the difference between psoriasis and eczema?
Psoriasis usually forms thick, well-defined, scaly plaques on the elbows, knees and scalp, while eczema is usually drier, less clearly edged, very itchy and found in skin creases. Our psoriasis vs eczema guide explains the differences in full.
Does psoriasis get worse with age?
Not necessarily. It tends to come and go throughout life, and many people find it settles with the right treatment. Stress, illness, some medicines, smoking and weight gain can make it worse at any age.
References
- NHS. Psoriasis. nhs.uk
- NICE Clinical Knowledge Summaries. Psoriasis. cks.nice.org.uk
- NICE. Psoriasis: assessment and management (CG153). nice.org.uk
- British Association of Dermatologists. Psoriasis: an overview (patient information leaflet), August 2023. skinhealthinfo.org.uk
- MHRA. Topical corticosteroids: information on the risk of topical steroid withdrawal reactions. Drug Safety Update, September 2021. gov.uk
Medical disclaimer: This article is for information only and isn’t medical advice. Prescription psoriasis treatments need a clinical consultation before they can be supplied. If your skin is red all over, you have widespread pus spots, a fever or you feel unwell, seek medical advice the same day. In a medical emergency, call 999.
