Psoriasis is a common chronic skin disease that comes in different forms and varying levels of severity. It affects some 2–3 % of the population. In Finland, psoriasis is estimated to affect some 150 000 people.

Psoriasis is often called an “immune-mediated” disorder, since it is related to the immune system. Psoriasis develops when the body’s immune system triggers rapid growth and shedding of skin cells. Immature skin cells build up on the skin’s surface and form red, flaky lesions that often itch and may crack and bleed.

There are several types of psoriasis, each of which have their characteristic forms of lesions:

1. plaque psoriasis
2. inverse psoriasis
3. guttate psoriasis
4. palmer psoriasis
5. erythrodermic psoriasis

The lesions typically develop on the scalp, knees, elbows and upper body. In addition to the lesions on the skin, psoriasis may cause symptoms on the nails, making the nails thick, pitted and discoloured. Nail can also separate from underlying skin. A percentage of people who have psoriasis will go on to develop an inflammation of the joints (psoriatic arthritis).


Who gets it?
Psoriasis is not contagious — no one can "catch" it from another person. There is a genetic component related to psoriasis. Certain people carry genes that make them more likely to develop psoriasis, but not everyone with these genes develops psoriasis. Beside the genetic component, there are several triggering factors that affect the outbreak of psoriasis or sometimes trigger a flare. These include stress, some medications, systemic infections, smoking, excessive alcohol use and skin injury.