Psoriasis is an autoimmune disorder that causes lesions or inflamed scaly patches on your skin. It can show up anywhere on your body, depending on the type(s) of psoriasis you have. 

Psoriasis is believed to be caused by abnormal immune system activity that’s directed at the cells making up your skin and nails. It’s not curable, but it can be managed. 

It comes in many types, but plaque psoriasis is by far the most common, making up between 85% and 90% of cases. Some people may have more than one type.

Frequently Asked Questions

  • Is psoriasis contagious?

    Many rashes are contagious, but psoriasis is not.

    This disease can run in families, which can lead to confusion about transmission. However, researchers believe this is due to a genetic glitch in the immune system and not anything you can “catch.”

  • What does psoriasis look like?

    The look varies by type:

  • What causes psoriasis? Is it an autoimmune disease?

    Yes, psoriasis is an autoimmune disease. Experts still don’t know why, but the immune system mistakenly attacks healthy skin or nail tissues like it would a real threat, such as a virus.

    Researchers believe a genetic predisposition combines with other factors—such as obesity, stress, or certain medical conditions—to trigger the disorder.

  • What is plaque psoriasis?

    Plaque psoriasis is by far the most common type of psoriasis. It’s characterized by well-defined patches of discolored skin that are itchy, scaly, and flaky. These are called plaques, and they’re caused by skin cells reproducing too quickly, so that they build up on the outermost layer of skin.

  • Is psoriasis itchy?

    Most types of psoriasis are extremely itchy, especially erythrodermic, guttate, and plaque psoriasis. This is due to dry, flaking, and sometimes peeling or cracking skin.

    These and other types of psoriasis may also include pain, which can be severe in some cases.

What Psoriasis Looks Like Under the Skin

Explore an interactive model showing how a psoriasis rash affects the outermost layer of the skin. This layer is typically comprised of a barrier of dead skin cells that continuously shed and are replaced by new cells. In psoriasis, however, the dead skin cells build upon each other, forming a thick, tough layer of cells that eventually flake off.

Key Terms

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  8. National Psoriasis Foundation. Life with psoriasis. Updated October 2, 2020.