Psoriasis is a chronic skin disease. Researchers believe this condition develops due to a combination of immune, genetic, and environmental factors. Psoriasis can start at any age. It is most common between ages 30 and 39 and also between ages 50 and 69. Psoriasis affects nearly equal numbers of men and women. In people with this disease, the skin grows too fast. Dead skin cells build up on the skin’s surface to form inflamed, thick, silvery scales called plaques. Sometimes people form many small lesions that can hurt or have pus in them. Psoriasis does not spread from person to person.

Psoriasis plaques tend to form on the elbows, knees, scalp, navel, arms, legs, and the penis or vulva. They can be unsightly, painful, and itchy. Plaques on the joints can limit movement. On the fingernails or toenails, psoriasis can cause pitting, a change in nail color, and a change in nail shape. In some cases, psoriasis also causes arthritis. Symptoms may come and go on their own. Factors such as stress, infection, and certain medicines may cause flare-ups. If symptoms bother you, many effective medical treatments are available to help relieve symptoms. Discuss your treatment options with your health care provider.