Psoriasis has some very distinctive signs and symptoms. The most distinctive of these being the psoriatic lesion as it is sharply defined against the normal skin. Characteristically it is a discrete, bright red patch covered with thick, silvery scales. There may be one lesion or there may be many. They usually have a striking symmetrical distribution.

The silvery scales are the many immature cells, which have formed and if scraped away the dark red base of the lesion is exposed. The colour is the result of an increase blood supply forming to feed the many forming cells.

Other symptoms of psoriasis include dry skin and inflammation. Although some may say their psoriasis does not itch the condition is usually very itchy, especially when the patches are spread over a large area of skin.

The continuous itch and the unsightly appearance of the lesions often lead to emotional problems. This may be the most damaging symptom and the most difficult to treat.

Another very distinctive symptom of psoriasis is the involvement of the nails. One quarter to one half of people with psoriasis develop pitting and discolouration of the nails and crumbling beneath the free edges. The nail plate may actually separate.