Under normal circumstances, skin cells are replaced over 21 to 28 days, but in psoriasis this takes just two to three days, these new skin cells gather and push up at the skin surface, forming a raised red rash with silvery scales which are called plaques.
The rash can be very uncomfortable and itchy. It usually appears on the knees, elbows or scalp, but can appear anywhere on the body. It can make people feel very self-conscious about the way they look, with many covering up so their skin is not seen in public.
Why does it happen?
No one knows precisely what causes psoriasis, but it does tend to run in families.
It often seems to be triggered by any of the following:
- a sore throat or chest infection
- burns, sunburn or other skin injury
- a stressful life event such as an exam, relationship problems or bereavement
Can I stop it?
It's difficult to know what to do to avoid it because so little is understood about why psoriasis starts in the first place. Usually, keeping stress levels at a minimum and the immune system strong may help keep infections away .
Should I see a doctor?
Although there is no cure for psoriasis, treatment is available from your doctor. It's important to get the diagnosis confirmed, since many skin rashes look similar but need different treatments. Your doctor should be able to do this | 
