Psoriasis: symptoms, treatment, causes and triggers

The NHS says how psoriasis is treated depends on the type, how severe it is and where it is on the body. You may need a combination of treatments. A GP can prescribe some, or you may be referred to a skin specialist (dermatologist). NHS inform says it may take time to find the best one for you, and that topical treatments may take up to 6 weeks to have a noticeable effect.

The NHS says the main symptom is dry, itchy, sore, flaky patches of skin that form what look like silvery-white scales. Patches are usually 1 to 2cm in size and oval or irregular in shape. They look pink or red on white skin, turning silvery-white, and are grey on brown or black skin, sometimes leaving dark marks after the psoriasis has gone.

Most people get only a few patches, others across large parts of the body. It is mostly found on the head and behind the ears, chest, tummy and back, bottom, forearms and elbows, and lower legs and knees, and can occur in body folds and on nails, which may have dents and pits. Symptoms often start between the ages of 15 and 25, or 50 and 60.

NHS inform says many people have only one type at a time, though two can happen together and one type may change into another.

No. The NHS says psoriasis is not contagious, so you cannot catch it or spread it. NHS inform says the same. The NHS says it is caused by the skin making more skin cells than usual, which creates patches, and is thought to be caused by a problem with the immune system.

NHS inform says skin cells are usually replaced every 3 to 4 weeks, but in psoriasis the process takes about 3 to 7 days, causing a build-up of cells. The immune system attacks healthy skin cells by mistake. The NHS says you are more likely to have it if a family member has psoriasis.

The NHS lists triggers that can make psoriasis worse or cause a flare-up. NHS inform adds hormonal changes, injury to the skin such as sunburn, and some medicines including lithium, some antimalarials, ibuprofen and ACE inhibitors.

• stress

• drinking alcohol or smoking

• living with obesity

• being pregnant

• certain medicines

• infections such as strep A and HIV

• cuts, scratches or grazes on the skin

• sunlight

The NHS suggests trying to avoid your triggers, eating a healthy, balanced diet, getting regular exercise, reducing stress if you can, drinking less alcohol and stopping smoking. It does not recommend a specific psoriasis diet. NICE Clinical Knowledge Summaries lists weight loss, smoking cessation and alcohol reduction as lifestyle advice.

The NHS also gives safety points for emollients: do not share them, use a spoon, spatula or pump rather than putting fingers in the pot, and do not smoke or go near naked flames if you use an emollient, because clothing and bedding that has been in contact with it burns more easily.

The NHS says some people with psoriasis develop psoriatic arthritis, an inflammatory condition affecting the joints, as they get older. Other complications can include metabolic syndrome (which can lead to diabetes, cardiovascular disease and DVT) and inflammatory bowel disease such as Crohn's disease. NICE Clinical Knowledge Summaries lists anxiety and depression as associated conditions and advises assessing cardiovascular risk at least every 5 years, especially if psoriasis is severe.

NICE Clinical Knowledge Summaries advises seeking urgent medical advice if there is unexplained joint pain or swelling, as this may be a sign of psoriatic arthritis that needs rheumatology referral.

The NHS says to see a GP if you have symptoms of psoriasis, if your treatment is not working or is giving you side effects, or if you also have joint pain, stiffness and swelling that keeps coming back.

Call 999 or go to A&E if you have psoriasis and your skin quickly turns red with white, pus-filled bumps that join together, patches on your feet turn yellow-brown and are filled with pus, or your fingers and toes have red, scaly pus-filled bumps on the tips. These can be signs of a more serious condition or an infection, and you may have a fast heartbeat or high temperature, the NHS says.

The NHS says that if you are planning to have a baby or are pregnant you may need to change your treatment, as some medicines can be harmful, and pregnancy can sometimes make symptoms worse. Speak to your doctor or a pharmacist if you are pregnant or trying to get pregnant.

On the NHS most people are treated by their GP with creams and emollients. NICE Clinical Knowledge Summaries lists dermatology referral where the diagnosis is uncertain, psoriasis is extensive (for example, more than 10% of the body surface), at least moderately severe, not responding to topical treatments, has severe nail disease, or has a significant impact on wellbeing. Light therapy and systemic treatments are specialist treatments. Private dermatology consultations are also available.