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Psoriasis

Information About Psoriasis

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Updated February 04, 2014

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Psoriasis affects 2.2% of the United States population and 1% to 3% of the world's population. It's a chronic skin disorder that is characterized by periodic flare-ups of well defined, red patches covered by a silvery, flaky skin on the extensor surfaces and the scalp.

What Causes Psoriasis

The exact cause of psoriasis is unknown, but most researchers believe that a combination of several factors contributes to the development of this disease. Some contributing factors include:
  • Gene mutations
  • Overactive immune system
  • Environmental causes

What Triggers Psoriasis

Environmental causes can trigger a psoriasis flare in people who have psoriasis. The good news is that avoiding these triggers can cut down of the number or severity of the flares. The bad news? Some are hard to avoid. Some of the more common psoriasis triggers include:
  • Skin injury
  • Weather
  • Stress
  • Infection
  • Low levels of calcium

Types of Psoriasis

Part of the reason psoriasis is such a complicated disease is that there are several different types of psoriasis. A person with psoriasis can have one or more of them, and the type could change throughout the person's lifetime.

Examples of the types of psoriasis include:

Psoriasis Appearance

Each type of psoriasis has a particular appearance, but there are characteristics of the rash that are shared by the majority of the types:
  • Thick, silvery scales on a very red base
  • Sharply outlined borders; the difference between normal skin and rash is distinct
  • Healing from the inside out, resembling ringworm

Psoriasis Picture Gallery

Psoriasis Treatment

There are numerous treatment options for psoriasis, some of which have been around for decades and others for less than 5 years. The majority of psoriasis cases can be treated with medications you apply to the skin (topicals), but the more severe cases may require oral or injected medicine. Types of medicine used to treat psoriasis include:
  • Topical medications
  • Phototherapy
  • Traditional oral medications
  • Immunobiologic medications

If you suspect psoriasis, see a dermatologist before attempting to self-treat.

Sources:

Habif, Thomas. "Psoriasis and other Papulosquamous Diseases." Clinical Dermatology, 4th Ed. Philadelphia: Mosby, 2004. 209-66.

Levine, D, and A Gottlieb. "Evaluation and management of psoriasis: an internist's guide." Medical Clinics of North America. 93(2009): 1291-303.

Menter, A, and CE Griffiths. "Current and future management of psoriasis." Lancet. 370(2007): 272-84.

Schon, Michael, and W.-Henning Boehncke. "Psoriasis." The New England Journal of Medicine 352(2005): 1899-912.

van de Kerhof, PCM and Joost Schalkwijk. "Psoriasis." Dermatology, 2nd Ed. Eds. Jean Bolognia, and et. al. Mosby, 2008. 115-35.

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