Psoriasis is a chronic immune disorder characterized by thick, red, scaly patches that itch and bleed. It affects nearly 7 million Americans.

Psoriasis often begins before age 35, but it can develop at any age. It occurs about equally among men and women. Visible patches of psoriasis sometimes are mistaken for infections or open wounds, but psoriasis is not contagious.

Although the cause is unknown, psoriasis is believed to have a genetic component that triggers the immune system to produce skin cells at a much faster rate than normal.

Skin cells usually mature and are shed from the body in 28-30 days. In people with psoriasis, these skin cells take only 3-4 days to mature and move to the surface. Instead of falling off, the cells accumulate and form lesions (patches).