Psoriasis is an immune-mediated disease that causes raised, red, scaly patches to appear on the skin.
Last reviewed on by the National Psoriasis Foundation
Psoriasis typically affects the outside of the elbows, knees or scalp, though it can appear on any location. Some people report that psoriasis is itchy, burns and stings. Psoriasis is associated with other serious health conditions, such as diabetes, heart disease and depression.
If you develop a rash that doesn't go away with an over-the-counter medication, you should consider contacting your doctor.
How do I get psoriasis?
While scientists do not know what exactly causes psoriasis, we do know that the immune system and genetics play major roles in its development. Usually, something triggers psoriasis to flare. The skin cells in people with psoriasis grow at an abnormally fast rate, which causes the buildup of psoriasis lesions.
Men and women develop psoriasis at equal rates. Psoriasis also occurs in all racial groups, but at varying rates. About 1.9 percent of African-Americans have psoriasis, compared to 3.6 percent of Caucasians.
Psoriasis often develops between the ages of 15 and 35, but it can develop at any age. About 10 to 15 percent of those with psoriasis get it before age 10. Some infants have psoriasis, although this is considered rare.
Psoriasis is not contagious. It is not something you can "catch" or that others can catch from you. Psoriasis lesions are not infectious.
How is psoriasis diagnosed?
There are no special blood tests or tools to diagnose psoriasis. A dermatologist (doctor who specializes in skin diseases) or other health care provider usually examines the affected skin and determines if it is psoriasis.
Your doctor may take a piece of the affected skin (a biopsy) and examine it under the microscope. When biopsied, psoriasis skin looks thicker and inflamed when compared to skin with eczema.
Your doctor also will want to learn about your family history. About one-third of people with psoriasis have a family member with the disease, according to dermatologist Dr. Paul Yamauchi with the Dermatology and Skin Care Institute in Santa Monica, Calif.
What type of psoriasis do I have?
There are five types of psoriasis. Learning more about your type of psoriasis will help you determine the best treatment for you.
Plaque psoriasis is the most common form of the disease and appears as raised, red patches covered with a silvery white buildup of dead skin cells. These patches or plaques most often show up on the scalp, knees, elbows and lower back. They are often itchy and painful, and they can crack and bleed.
Guttate [GUH-tate] psoriasis is a form of psoriasis that appears as small, dot-like lesions. Guttate psoriasis often starts in childhood or young adulthood, and can be triggered by a strep infection. This is the second-most common type of psoriasis, after plaque psoriasis. About 10 percent of people who get psoriasis develop guttate psoriasis.
Inverse psoriasis shows up as very red lesions in body folds, such as behind the knee, under the arm or in the groin. It may appear smooth and shiny. Many people have another type of psoriasis elsewhere on the body at the same time.
Pustular [PUHS-choo-lar] psoriasis in characterized by white pustules (blisters of noninfectious pus) surrounded by red skin. The pus consists of white blood cells. It is not an infection, nor is it contagious. Pustular psoriasis can occur on any part of the body, but occurs most often on the hands or feet.
Erythrodermic [eh-REETH-ro-der-mik] psoriasis is a particularly severe form of psoriasis that leads to widespread, fiery redness over most of the body. It can cause severe itching and pain, and make the skin come off in sheets. It is rare, occurring in 3 percent of people who have psoriasis during their life time. It generally appears on people who have unstable plaque psoriasis.
Individuals having an erythrodermic psoriasis flare should see a doctor immediately. This form of psoriasis can be life-threatening.
Where does psoriasis show up?
Psoriasis can show up anywhere—on the eyelids, ears, mouth and lips, skin folds, hands and feet, and nails. The skin at each of these sites is different and requires different treatments.
Light therapy or topical treatments are often used when psoriasis is limited to a specific part of the body. However, doctors may prescribe oral or injectable drugs if the psoriasis is widespread or greatly affects your quality of life. Effective treatments are available, no matter where your psoriasis is located.
Scalp psoriasis can be very mild, with slight, fine scaling. It can also be very severe with thick, crusted plaques covering the entire scalp. Psoriasis can extend beyond the hairline onto the forehead, the back of the neck and around the ears.
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Facial psoriasis most often affects the eyebrows, the skin between the nose and upper lip, the upper forehead and the hairline. Psoriasis on and around the face should be treated carefully because the skin here is sensitive.
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Treat sudden flares of psoriasis on the hands and feet promptly and carefully. In some cases, cracking, blisters and swelling accompany flares. Nail changes occur in up to 50 percent of people with psoriasis and at least 80 percent of people with psoriatic arthritis.
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The most common type of psoriasis in the genital region is inverse psoriasis, but other forms of psoriasis can appear on the genitals, especially in men. Genital psoriasis requires careful treatment and care.
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Inverse psoriasis can occur in skin folds such as the armpits and under the breasts. This form of psoriasis is frequently irritated by rubbing and sweating.
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How severe is my psoriasis?
Psoriasis can be mild, moderate or severe. Your treatment options may depend on how severe your psoriasis is. Severity is based on how much of your body is affected by psoriasis. The entire hand (the palm, fingers and thumb) is equal to about 1 percent of your body surface area.
However, the severity of psoriasis is also measured by how psoriasis affects a person's quality of life. For example, psoriasis can have a serious impact on one's daily activities even if it involves a small area, such as the palms of the hands or soles of the feet.
Mild psoriasis covers less than 3 percent of the body.
Moderate psoriasis covers between 3 and 10 percent of the body.
If psoriasis covers more than 10 percent of your body, it is severe.
Topical treatments, such as moisturizers, over-the-counter and prescriptions creams and shampoos, typically are used for mild psoriasis.
Treating moderate to severe psoriasis usually involves a combination of treatment strategies. Besides topical treatments, your doctor your doctor may prescribe phototherapy (also known as light therapy). Your doctor may also prescribe systemic medications, including biologic drugs, especially if your psoriasis is significantly impacting your quality of life.
Will I develop psoriatic arthritis?
About 11 percent of those diagnosed with psoriasis have also been diagnosed with psoriatic arthritis. However, approximately 30 percent of people with psoriasis will eventually develop psoriatic arthritis.
Psoriatic arthritis often may go undiagnosed, particularly in its milder forms. However, it's important to treat psoriatic arthritis early on to help avoid permanent joint damage. Learn more about psoriatic arthritis.
What about psoriasis in children?
Every year, roughly 20,000 children under 10 years of age are diagnosed with psoriasis. Sometimes it is misdiagnosed because it is confused with other skin diseases. Symptoms include pitting and discoloration of the nails, severe scalp scaling, diaper dermatitis or plaques similar to that of adult psoriasis on the trunk and extremities. Psoriasis in infants is uncommon, but it does occur. Only close observation can determine if an infant has the disease.
If one parent has the disease, there is about a 10 percent chance of a child contracting it. If both parents have psoriasis, the chance increases to 50 percent. No one can predict who will get psoriasis. Scientists now believe that at least 10 percent of the general population inherits one or more of the genes that create a predisposition to psoriasis. However, only 2 to 3 percent of the population develops the disease.
Some young people report the onset of psoriasis following an infection, particularly strep throat. One-third to one-half of all young people with psoriasis may experience a flare-up two to six weeks after an earache, strep throat, bronchitis, tonsillitis or a respiratory infection. Areas of skin that have been injured or traumatized are occasionally the sites of psoriasis, know as the “Koebner [keb-ner] phenomenon.” However, not everyone who has psoriasis develops it at the site of an injury.
Do you have additional questions about psoriasis?