Home > Get the Facts

Psoriasis is a chronic (lifelong) skin disease characterized by flaking skin (scaling) and inflammation. It affects as many as 7.5 million Americans. Psoriasis often appears between the ages of 15 and 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.

What causes psoriasis?

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 to 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).

Types of psoriasis and their symptoms

Plaque psoriasis is the most common type of psoriasis, affecting about 80% of all people with psoriasis. It causes red, raised lesions of dead, flaky skin cells. These lesions may be sore or itchy.

Plaque psoriasis usually occurs on the elbows, knees, scalp, and torso, but it can develop on any skin surface, including the palms, soles of the feet, genitals, and face (which is rare).

Other types of psoriasis include:

• Guttate: Small, red spots, usually found on the trunk, arms, and legs
• Inverse: Small, red lesions that may be smooth and shiny; found in skin folds
• Pustular: White blisters surrounded by red areas
• Erythrodermic: Widespread, fiery redness over large areas

Link between psoriasis and psoriatic arthritis

Up to 30% of people with psoriasis also get joint pain and stiffness. If you’re experiencing stiffness and joint pain, as well as the skin symptoms of psoriasis, it could mean you have a condition known as psoriatic arthritis (PsA). Talk to your doctor to learn more about PsA.

Living well

In addition to the physical impact on the skin, the visible and chronic nature of psoriasis can impact your emotional and social well-being. Get tips to help you live well with psoriasis.