What Is Psoriasis?

Psoriasis is a common long-term (chronic) skin disease. There are several types of psoriasis. The most common type is plaque psoriasis. Researchers think psoriasis develops from a combination of immune, genetic, and environmental factors.

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 have many small lesions that can hurt or that have pus in them.

Psoriasis doesn't spread from person to person. It may occur at any age, but is most often seen in people ages 15 to 22 and also between ages 55 and 70. It affects both men and women equally.

Psoriasis plaques most often form on the elbows, knees, scalp, navel, arms, legs, and the penis or vulva (genital areas). 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. Stress, infection, and certain medicines may cause flare-ups. If symptoms bother you, many treatments are available to help ease symptoms. Discuss your treatment choices with your doctor.

There are many types of medicines that can treat the affected skin lesions. Your doctor may prescribe medicine, such as:

• Topical medicines. These are medicines that are put on the skin. These include moisturizers, steroids, types of vitamin D, medicines made from vitamin A (retinoids), and other nonsteroid medicines. You can use them on a regular basis.
• Coal tar. This is an effective solution that may be added to bath, shampoo, and ointment products. It is not advised for genital psoriasis. Your doctor may advise coal tar alone or along with other treatment choices.
• Phototherapy. In some cases, your skin may be exposed to a special light in the doctor's office. Or you can expose the psoriatic plaques to short periods (5 minutes) of natural sun as advised by your doctor. Phototherapy can be helped with a type of medicine called psoralen.

Internal treatments are taken by mouth (oral) or given by shot (injection). A number of new oral and injectable medicines can treat severe psoriasis. Your doctor can tell you more about these treatments.