Psoriasis is an immune-mediated condition often marked by thick red patches with silvery scales on the elbows, knees, and scalp. There’s no cure for psoriasis yet, but treatment can help ease the symptoms.

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Psoriasis causes itchiness and irritation and may be painful.

While scientists don’t know what exactly causes psoriasis, they do know that the immune system and genetics play major roles in its development.

Read on to get the scoop on psoriasis causes, prevalence, symptoms, treatment options, and more.

Psoriasis usually causes patches of thick, red skin with silvery scales that itch or feel sore.

It can show up anywhere — on the eyelids, ears, mouth and lips, skin folds, hands and feet, scalp, and nails.

In severe cases, it can progress to cover large areas of your body and cause a variety of uncomfortable symptoms.

In people with light skin, it tends to appear red or pink with a silvery-white scale. In people with dark skin, it may appear salmon-colored or violet with a silvery-white or grayscale. It may also be harder to spot.

You may have occasional flare-ups followed by times when you don’t have symptoms.

Learn more: What to know about psoriasis symptoms and psoriasis on black skin vs. white skin.

About 2-3% of the world’s population has some form of psoriasis, according to the World Psoriasis Day consortium. That’s over 125 million people.

Anyone can get psoriasis, regardless of age. However, psoriasis is most likely to appear first between the ages of 15–25 years, according to the National Psoriasis Foundation.

In the United States, the condition affects about 3.2% of women and 2.8% of men, according to a combination of a 2021 study and 2020 U.S. census data. In total, that’s just over 7.4 million people ages 20 years or older.

Prevalence by type

The types of psoriasis with their prevalence are:

Psoriasis typePrevalence
plaque psoriasis80–90% of cases
scalp psoriasis45–56% of people with psoriasis
nail psoriasis50% of people with psoriasis
guttate psoriasis8% of people with psoriasis
inverse psoriasis21–30% of people with psoriasis
pustular psoriasis3% of people with psoriasis
erythrodermic psoriasis2% of people with psoriasis

Note that 30–33% of people with psoriasis can also develop psoriatic arthritis, which is a type of arthritis.

Learn more about the types of psoriasis, their symptoms, and what they look like.

The exact cause of psoriasis isn’t known, though research suggests that psoriasis could be an autoimmune disease and that some autoantigens might be connected to its development.

In your immune system, it’s the job of your T cells to attack foreign organisms to keep you healthy. For those with psoriasis, the T cells mistakenly attack healthy skin cells. This leads to an overproduction of new skin cells, T cells, and white blood cells.

This leads to dead skin cells accumulating. The accumulation creates the hallmark scaly patches seen in psoriasis.

No type of psoriasis is contagious. You cannot catch psoriasis from someone who has it.

Who is most at risk for psoriasis?

Many people with psoriasis have a family history of the disease. Researchers have found some genes linked to psoriasis.

You’re more likely to develop psoriasis if one of your parents has it. The heritability of the condition is estimated at about 60–90%.

Other risk factors include:

Flare-ups may also be brought on by emotional stress or triggered by certain drugs, weather, or alcohol.

Learn more: Psoriasis risk factors.

Despite its considerable effect on quality of life, psoriasis is underdiagnosed and undertreated. If you suspect you may have psoriasis, contact a board certified dermatologist who can examine your skin, nails, and scalp for signs of the condition.

In most cases, a medical professional can typically conduct a physical exam and review your medical history to make a diagnosis.

If there’s any doubt, your medical professional may do a biopsy to confirm the diagnosis. Psoriatic arthritis will need additional testing.

Learn more: How is psoriatic arthritis diagnosed?

There’s currently no cure for psoriasis, but treatment can slow down the growth of skin cells and relieve pain, itching, and discomfort.

Treatments can be divided into three main types, though medical professionals may combine more than one type:

  • topical treatments such as corticosteroids
  • light therapy
  • systemic medications

The best treatment varies by individual, taking into consideration the type of psoriasis you have, where it is on your body, and the possible side effects of medications.

For mild cases, there is a variety of over-the-counter (OTC) topical ointments that can help. There are also a number of things you can do at home that can help treat the symptoms of psoriasis.

Learn more about psoriasis treatments.

While medication can reduce or clear psoriasis, anything that irritates your skin can cause psoriasis to flare — even when you use medication. Because the condition is chronic, psoriasis can significantly affect your quality of life.

In addition, having psoriasis can negatively affect your mental health. Frequent bouts of psoriasis can cause people to withdraw from social situations or work. This may lead to feelings of depression.

In fact, a 2022 research review indicates people living with psoriasis are 1.5 times more likely to experience depression and anxiety than people without psoriasis.

When living with a chronic condition like psoriasis, having peer support can be helpful. Bezzy Psoriasis is a judgment-free communal space where you can get advice, read stories, and connect with other people living with psoriasis.

If you have psoriasis, see your medical professional as often as recommended. They can help you create a treatment plan that works for you.

Because of the risk of complications, your medical professional will likely do regular exams and screenings to check for related conditions.

Jen Thomas is a journalist and media strategist based in San Francisco. When she’s not dreaming of new places to visit and photograph, she can be found around the Bay Area struggling to wrangle her blind Jack Russell Terrier or looking lost because she insists on walking everywhere. Jen is also a competitive Ultimate Frisbee player, a decent rock climber, a lapsed runner, and an aspiring aerial performer.