Psoriasis by the Numbers: Facts, Statistics, and You

Medically reviewed by George T. Krucik, MD, MBA and Aleah Rodriguez, PharmD on June 9, 2016Written by Ann Pietrangelo on January 9, 2015


Psoriasis is a chronic skin condition. It causes cells to build up quickly on your skin’s surface. This leads to raised patches of skin that develop silver scales. Psoriasis causes itchiness and irritation and may be painful. There is no cure for psoriasis, but treatment can ease symptoms.


Anyone can get psoriasis, regardless of age. Psoriasis is most likely to appear first during your twenties or fifties. Males and females get it at about the same rate.

According to the International Federation of Psoriasis Associations (IFPA), about 3 percent of the world’s population has some form of psoriasis. In the United States, there are about 150,000 new cases every year. It affects about 2 percent of the U.S. population, according to the Cleveland Clinic.


Psoriasis causes patches of red, rough skin. In mild cases, it may cause patches of dry, itchy skin on your scalp. In severe cases, it can spread over large areas of your body and cause a variety of uncomfortable symptoms.

With psoriasis, your red, rough skin takes on the appearance of silver scales. Your skin may also be dry and cracked, which can make it bleed. Your fingernails and toenails can become thick and pitted. You may have occasional flare-ups followed by times when you don’t have symptoms.

Types of psoriasis

Plaque psoriasis

According to the American Academy of Dermatology, this is the most common type of psoriasis. It makes up about 80 percent of cases. It causes red skin lesions and silver scales that can occur anywhere on the body. These can even appear on the inside your mouth or on your genitals. Plaque psoriasis can be itchy and painful.

Scalp psoriasis

Psoriasis can also occur on your scalp. Symptoms include dry, itchy scalp. You may also notice flakes in your hair and on your shoulders. Scratching can cause bleeding.

Nail psoriasis

Psoriasis of the fingernails and toenails can cause your nails to appear pitted and discolored. The nails can get weak and crumble. They may even separate from your nail bed. When this happens, it’s called onycholysis.

Psoriatic arthritis

According to the Centers for Disease Control and Prevention, about 10 to 20 percent of people with psoriasis go on to develop psoriatic arthritis. The IFPA puts the figure as high as 30 to 50 percent. As with other types of arthritis, symptoms include joint stiffness and swelling.

Guttate psoriasis

This type of psoriasis can be brought on by a bacterial infection. It generally affects children and young adults. Skin sores appear on the scalp, torso, arms, and legs. The scales are finer than those from other types of psoriasis. Some people with this type have only one outbreak that clears up without treatment. But other people continue to have outbreaks over time.

Inverse psoriasis

This type of psoriasis may cause patches of red, irritated skin in your armpits, under your breasts, or around your genitals and groin. This type may be triggered by a fungal infection. Perspiration can make symptoms worse. You’re more likely to get inverse psoriasis if you’re obese.

Pustular psoriasis

This rare type of psoriasis can come on quickly. First, your skin becomes red and tender to the touch. Within hours, pus-filled blisters appear. Blisters may clear up and come back from time to time. Flare-ups may be triggered by infection, irritation, or even by some medications. In addition to itching, pustular psoriasis can cause fever, chills, diarrhea, and kidney and liver problems. These issues can be severe. You may need to be hospitalized to treat them.

Erythrodermic psoriasis

This uncommon type of psoriasis can affect your whole body. Symptoms include red, peeling skin, itchiness, and burning sensation. Medications, such as corticosteroids, may trigger erythrodermic psoriasis. Other triggers include phototherapy treatment, sunburn, and psoriasis that has spread out of control.

Cause and risk factors

The exact cause of psoriasis is not known. It involves a problem with your immune system response. In your immune system, it’s the job of your T-cells to attack foreign organisms to keep you healthy. In 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 allows dead skin cells to accumulate. The accumulation creates the hallmark scaly patches seen in psoriasis.

According to the Cleveland Clinic, genetics may play a role in the condition. You’re more likely to get psoriasis if one of your parents has it. Your risk is even higher if both of your parents have it.

Bacterial or viral infections may also be a factor. According to the Mayo Clinic, you’re at greater risk of getting psoriasis if you have HIV. Children with frequent bouts of strep throat or other recurring infections also have a higher risk. Because psoriasis often begins in the folds of the skin, you’re at greater risk if you’re overweight or obese.

Certain medications may also play a role. Lithium, beta blockers, tetracycline, nonsteroidal anti-inflammatory drugs (NSAIDs), and malaria drugs are linked to psoriasis.

Smokers have a higher risk of psoriasis. If you already have the condition, smoking may make it worse. Flare-ups may be brought on by stress or triggered by certain drugs. These include beta blockers, interferon, and lithium.

No type of psoriasis is contagious. You can’t catch psoriasis from someone who has it.

Tests and diagnosis

In the United States, primary care doctors are the first line of care in 58 percent of new cases. According to the Cleveland Clinic, psoriasis causes 3 million office and hospital visits per year. Dermatologists manage 80 percent of these cases. These are doctors who specialize in treating skin conditions.

In many cases, a doctor can diagnose psoriasis by conducting a physical exam and reviewing your medical history. If there’s any doubt, your doctor may do a biopsy to confirm the diagnosis.

Learn more: Skin biopsy for psoriasis »


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

For mild cases, there are a variety of over-the-counter topical ointments that can help. Prescription corticosteroids can also help, but they’re often only used during flare-ups. Other topical treatments include:

  • Calcipotriene (Dovonex) and calcitriol (Rocaltrol): These drugs are synthetic, or man-made, vitamin D. They work by slowing the growth of skin cells.
  • Anthralin (Dritho-Scalp): This medication regulates DNA activity in skin cells and remove scales.
  • Tazarotene (Tazorac): This is a derivative of vitamin A. It’s used to normalize DNA activity and decrease inflammation.
  • Tacrolimus (Prograf) and pimecrolimus (Elidel): These drugs work by reducing inflammation.
  • Salicylic acid: This drug is used to get rid of dead skin cells.
  • Coal tar: This medication works by reducing inflammation and scaling.
  • Moisturizers: These are used to sooth dry skin.

Light therapy and natural sunlight can also ease psoriasis symptoms. This is because light can slow skin cell growth and scaling.

Other treatment options are oral and injectable drugs. These include retinoids, methotrexate, and cyclosporine. Severe psoriasis may also be treated with biologics. Biologic drugs alter your immune system.

Read more: Biologics for psoriasis »


Having psoriasis increases your risk of psoriatic arthritis. It may also increase your risk of:

  • high blood pressure
  • cardiovascular disease
  • type 2 diabetes
  • kidney disease
  • Parkinson’s disease
  • other autoimmune disorders, such as Crohn’s disease and celiac disease
  • eye problems such as conjunctivitis, uveitis, and blepharitis

Psoriasis can also impact your quality of life. Frequent bouts of psoriasis can cause people to withdraw from social situations or work. This may lead to feelings of depression.

Keep reading: About psoriasis and depression »

Talk with your doctor

If you have psoriasis, see your doctor as often as they suggest. They can help you find a treatment that works for you. Because of the risk of complications, your doctor will do regular exams and screenings to check for related conditions.

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