Psoriasis Home > Psoriasis

Psoriasis, a skin disease characterized by scaling and swelling, is caused by a malfunction in the immune system. T cells in the immune system typically protect the body against infection and disease, but in psoriasis, T cells are put into action by mistake, causing swelling and fast turnover of skin cells. Treatments for this disease focus on correcting the scaly appearance of the skin.

What Is Psoriasis?

Psoriasis is a chronic skin disease that causes areas of thickened, swollen, and red skin, often covered with silver scales.
In people without psoriasis, skin cells grow deep in the skin and slowly rise to the surface. This process is called cell turnover, and it takes about a month. With psoriasis, it can happen in just a few days because the cells rise too fast and pile up on the surface.

Who Gets Psoriasis?

This disease affects 2 percent to 2.6 percent of the United States population, or between 5.8 and 7.5 million people. Anyone can get psoriasis, but it occurs more often in adults. Sometimes there is a family history of the disease. Certain genes have been linked to it, and men and women get psoriasis at about the same rate.

What Causes It?

This condition begins in the immune system, mainly with a type of white blood cell called a T cell. T cells help protect the body against infection and disease. With psoriasis, T cells are put into action by mistake. They become so active that they set off other immune responses. This leads to swelling and fast turnover of skin cells.
People with this condition may notice that sometimes the skin gets better and sometimes it gets worse. Things that can cause your symptoms to worsen include:
  • Infections
  • Stress
  • Changes in weather that dry the skin
  • Certain medicines.
(Click Psoriasis Causes for more information about the causes of this condition.)
Written by/reviewed by:
Last reviewed by: Arthur Schoenstadt, MD
Last updated/reviewed:
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