Psoriasis is a long term skin disease. It results in red, flaky, crusty patches of skin that are covered with silvery scales. They are most common on the elbows, knees, scalp, and lower back. But they can also appear on places like the nails, mouth, genitals, and joints. Some people may have small patches while others may have many. The patches can also go away and then come back. These are called flare-ups. They can be triggered by things like stress, medicines, and infections.
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The body swaps old skin cells with new ones about every month. In people with psoriasis, it only takes a week or less. It is not known why this happens. It is thought to be due to a problem with the body's immune system. Genetics may also play a role as this health problem tends to be more common in people who have other family members who have it.
There are five types:
Plaque: This is the most common type. It results in raised, red patches of skin that are covered by silvery-white scales.
Guttate: This type is more common in children and young adults. It results in small, red dots on the torso, arms, or legs. It is often triggered by an infection, such as strep throat.
Pustular: This type results in pus-filled blisters and red skin. It happens on the hands and feet, but there is a form that can cover most of the body. It is triggered by things like medicine, infections, stress, and certain chemicals.
Inverse: This type results in smooth, red patches in the folds of a person's skin, such as under the breasts or in the groin or armpits. Rubbing and sweating can make them worse.
Erythrodermic: This is a rare, severe type that results in red, scaly skin over most of the body. It can be triggered by a sunburn or by taking certain medicines, such as steroids. It is more likely to happen in people who have another type that is not being managed well.
Some people also get psoriatic arthritis. This happens when a person also has joint inflammation, most often in the hip, spine, knee, or elbow. It can also happen in the small joints of the hands and feet.
What are the risk factors for psoriasis?What are the symptoms of psoriasis?How is psoriasis diagnosed?What are the treatments for psoriasis?Are there screening tests for psoriasis?How can I reduce my risk of psoriasis?What questions should I ask my doctor?Where can I get more information about psoriasis?References
Psoriasis. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/psoriasis. Accessed March 25, 2022.
Psoriasis. National Institute of Arthritis and Musculoskeletal and Skin diseases. Available at: https://www.niams.nih.gov/health-topics/psoriasis. Accessed March 25, 2022.
Psoriasis resource center. American Academy of Dermatology website. Available at: https://www.aad.org/public/diseases/psoriasis. Accessed March 25, 2022.
Revision Information
- Reviewer: EBSCO Medical Review Board Daniel A. Ostrovsky, MD
- Review Date: 11/2021
- Update Date: 03/25/2022