What Causes Psoriasis?

Psoriasis is a common skin disorder, affecting about 1 in 40 persons. The cause of psoriasis is not known. Because many persons with psoriasis have blood relatives with this disorder, heredity probably plays a role.

In psoriasis, areas of the skin grow much faster than normal and form red, scaling patches. The scalp, elbows, and knees are the most common sites, but almost any part of the skin may become involved. Fortunately, psoriasis is only a skin condition, and does not affect your general health. (In rare cases there may be arthritis.) Psoriasis is a problem because it itches and is unsightly. Psoriasis is not contagious.

Psoriasis usually begins in young adulthood, although it can start in childhood or first appear in old age. In most cases psoriasis is mild and limited to a few areas of the body. In a small percentage of cases, large areas of the body may become involved. Psoriasis is unpredictable: Patches may clear up by themselves and even disappear for months or years.

Treating Psoriasis

Treatment for psoriasis is temporarily effective, and may need to be continued for quite a while. You will find it reassuring to know that (1) diet does not affect psoriasis, (2) psoriasis will not cause your hair to fall out, and (3) psoriasis is not caused by nerves. A high anxiety state sometimes worsens psoriasis—just as increased anxiety may worsen almost any other illness.

If you have psoriasis of the scalp, it helps to wash your hair often. A medicated shampoo is sometimes necessary. Some other treatments used in psoriasis are the following:

  1. Moderate sunlight exposure is often helpful. Don’t get sunburned, since psoriasis may settle in areas of injured skin.
  2. Ultraviolet light by itself often helps psoriasis. Ultraviolet light is even more effective when used with tar or anthralin.
  3. Cytotoxic drugs such as methotrexate, given by mouth or injection, are used only for very severe psoriasis. Cytotoxic means poisonous to cells, and these drugs are used only with special precautions.
  4. PUVA treatment combines a psoralen (an internal medicine) with ultraviolet light A (PUVA = Psoralen + UltraViolet A). This therapy is available only at certain centers (including ours), as it requires specialized light equipment. While PUVA is an effective treatment for extensive psoriasis, like all other treatments it is only of temporary benefit but may be long lasting.
  5. Psoriasis may be associated with other conditions (“metabolic syndrome”): arthritis, high cholesterol, high blood pressure, heart disease, and diabetes, and should be evaluated annually.

While psoriasis is an cosmetic nuisance, it should not prevent you from leading a full, active life.