What is Psoriasis?

Psoriasis is a skin disorder than can occur at any age in both men and women. Most commonly, psoriasis first appears as thick, flaky patches of skin on the elbows, knees, or other parts of the body. The patches may be silver or red.

The skin flaking that occurs in psoriasis is known as scaling. At first, a few small, flaky patches -- known as plaques-- may appear. Often, the plaques gradually enlarge and increase in number. Less commonly, psoriasis may erupt suddenly all over the body.

Psoriasis is a chronic disorder, which means it can last a long time and can come back frequently. It is most common in people in their 20s, 30s, and 40s. Psoriasis is rare under age 3. Most people who develop it do so before age 30. In the United States, about two or three out of every 100 people have psoriasis.

Psoriasis commonly occurs on pressure points such as the elbows, knees, and knuckles, as well as on the scalp, the trunk, the arms and legs, the external sex organs, and the fingernails and toenails.

The severity of psoriasis varies widely. The most common pattern is for the disease to be limited to certain parts of the body but to recur (come back) frequently. Once someone has had a flare-up of psoriasis, the chances are nine out of 10 that the disease will recur. Psoriasis that begins earlier in life tends to be more severe and persistent.

Usually people with psoriasis are otherwise healthy and feel well. However, if psoriasis affects large areas of the skin, it can seriously interfere with a person's ability to function normally. The thick, flaky patches of skin are often disfiguring and can be itchy or painful. If the hands or feet are affected, a person may have difficulty walking or holding a job. Caring for psoriasis is a daily, time-consuming process.

Psoriasis is an unpredictable condition that can sometimes flare up for no apparent reason. The course of the disease can be different in every individual who has it. People with psoriasis commonly go through periods of embarrassment, frustration, and depression about their condition. Because psoriasis affects exposed skin, it is a highly visible disease.

Psoriasis is not an infection and it is not contagious - you cannot "catch" it from anyone.

How Severe Can Psoriasis Get?

Psoriasis is defined as mild, moderate, or severe, depending on how much of the skin is affected.

• Mild psoriasis affects less than 2 percent of the skin.

• Moderate psoriasis affects 2 percent to 10 percent of the skin.

• Severe psoriasis affects more than 10 percent of the skin.

As a general rule, the palm of one hand is roughly equal to one percent of the skin.

What Is Psoriatic Arthritis?

In about one out of every 10 people with psoriasis, the disease causes pain and swelling in the joints. This is called psoriatic arthritis. This condition tends to wax and wane. It is less likely than other types of joint disease, such as rheumatoid arthritis, to worsen over time and become disabling.

People with psoriasis may also have more common forms of arthritis. Rarely, people with psoriatic arthritis may develop a disabling form of arthritis in which the joints become deformed.