Please note: This information was current at the time of publication but now may be out of date. This handout provides a general overview and may not apply to everyone. 

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Am Fam Physician. 1999;59(4):964

See related article on psoriasis.

What is psoriasis?

Psoriasis (say “sore-eye-a-sis”) is a skin problem. It causes red, silvery scales and flaky skin patches. It can get better or worse, but there's no cure. No one knows what causes psoriasis. It's not caused by something you ate or something you're allergic to. You can't catch it from other people or give it to someone by touching them.

How can my doctor tell I have psoriasis?

Your doctor can tell if you have psoriasis just by looking at your skin. In unusual cases, your doctor may need to do a biopsy (cutting out a small piece of skin to examine under a microscope).

How is psoriasis treated?

If your psoriasis is mild, you may not need any treatment. Just being in the sun may help your skin get rid of the rash. For a mild case, treatments that you can get without a prescription work well. These include moisturizing creams and shampoos for scalp psoriasis. Ointments that have salicylic acid in them can help you get rid of the scales. So can soaps, lotions, creams and ointments that contain coal tar (however, many people find coal-tar products messy and smelly). You can also try prescription creams that contain anthralin. These creams can stain your skin and clothes.

For more severe psoriasis, you can use prescription creams that have steroids in them, like cortisone. Long-term use of steroid creams can damage your skin and cause side effects that don't go away, like making your skin thin and bruised, and making the blood vessels in your skin get too large.

If you have psoriasis over a large area, your doctor may recommend phototherapy (light treatment). You'll probably go to a place that specializes in phototherapy. You'll stand under ultraviolet A light. To make the treatment work better, your doctor may have you take psoralen pills to boost the action of ultraviolet A light. This combination treatment—light plus psoralen—is called PUVA therapy (psoralen ultraviolet A light).

If your psoriasis doesn't get better with these treatments, your doctor may have you take methotrexate pills or etretinate or acitretin, which are forms of vitamin A. However, taking regular vitamin A doesn't help. All of these medicines can have serious side effects, including liver damage and birth defects.

One of the newer treatments is a cream or lotion that has a form of vitamin D in it, known as calcipotriene (say “cal-sip-o-treen”). This product helps three out of four people who use it. However, taking regular vitamin D doesn't help.

The newest topical medication for psoriasis is used directly on the skin. It's a gel called tazarotene. It contains a form of vitamin A. Women shouldn't get pregnant while using this medicine.

Where can I get more information about psoriasis?

For more information, contact the National Psoriasis Foundation, 6600 S.W. 92 Ave., Suite 300, Portland, OR 97223; telephone: 1-800-248-0886.

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