Psoriasis is a serious, chronic, relapsing skin ailment in which the involved skin areas produce silvery scales. The areas usually affected are the skin of the elbows, knees, back, buttocks and scalp. The lesions are large red plaques covered with overlapping, shiny, scales which are shed continuously.

The cause of psoriasis is vague. It appears that heredity is a factor in about one case out of three. The alteration in the skin is an overproduction of skin cells in the epidermis. The cells composing this surface layer of the skin are normally shed at such rate that average cell life is about twenty-eight days. Psoriasis on the other hand, the cells produced and shed only takes three to four days. Acute attacks of psoriasis usually end spontaneously, but may recur. The severity varies from person to person. It cannot be known in the early phase of the illness just how severe it will be.