Psoriasis by the Numbers

If you have psoriasis, you’re in good company. This chronic skin condition and autoimmune disorder—the most common in the U.S.—affects millions of people.

What causes psoriasis is not entirely clear, though the condition occurs when the immune system incorrectly speeds up the growth cycle of skin cells. Psoriasis flare-ups are thought to be prompted by a combination of genetic factors and environmental triggers, and in many patients, flare-ups are often accompanied by an itching, burning, or stinging sensation.

Psoriasis may go away for periods of time and then reappear suddenly in response to specific triggers, like stress, skin injuries, certain medications, allergies, diet, weather, smoking, and alcohol consumption. Not everyone who has psoriasis is affected by all of these, and individuals may have their own unique set of conditions that cause flare-ups.

Here’s a look at psoriasis by the numbers:

125 million. Number of people worldwide with psoriasis. That’s 2-3% of the population.

7.5 million. The number of Americans thought to have psoriasis.

10-30. The percent of psoriasis patients who develop psoriatic arthritis, which affects the joints.

2.5. The percentage of Caucasians with psoriasis; the percentage of African Americans with psoriasis is 1.3.

15-25. The age at which psoriasis usually first appears on the skin. However, the condition can appear at any age.

30-50. The age at which patients tend to first develop psoriasis symptoms.

80. Percentage of psoriasis patients with plaque psoriasis.

Plaque Psoriasis

This common form of the condition is characterized by raised, inflamed, red patches covered by a silvery white scale that typically appear on the elbows, knees, scalp and lower back. "Psoriasis is an extremely variable condition. It can be localized, widespread, or anything in between," explains Joyce Davis, MD, a dermatologist in private practice in New York City. "It classically creates skin lesions that resemble 'continents,' with raised, thick, red, scaling 'plaques,' which are surrounded by normal skin."

Plaques usually occur on areas like the elbows or knees, "but psoriasis can also involve the chest, fingernails (resembling a nail fungus), scalp, crease of the rectum, and genitalia (penis, labia, et cetera). Psoriasis can [also] can cause an accompanying arthritis." Finally, "Some people who develop psoriatic arthritis don't have major skin psoriasis but do have pitting (dimples) affecting the surface of their fingernails."

Up to 3 percent of the body is affected in patients with mild psoriasis. In patients with moderate psoriasis, 3 to 10 percent of the body is affected, and in patients with severe psoriasis, more than 10 percent of the body is affected. For reference, your hand equals about 1 percent of your skin’s surface, according to the National Psoriasis Foundation.

Almost 25 percent of psoriasis cases are considered moderate to severe.

Nearly 60 percent of psoriasis patients consider the condition to be a large problem in their everyday life.

63 percent of respondents in recent survey said their condition affected their overall emotional wellbeing.

$135 billion. Annual healthcare costs of psoriasis in the U.S. This equals about $26,000 per person.

Treating Psoriasis

"Treatments vary with the extent of the condition," says Davis. "Someone with just a few plaques or spots might need only a topical corticosteroid cream or ointment or other topical products containing tar or vitamin D. More stubborn lesions can be treated with injectable cortisone administered by a dermatologist or, in cases where the disease is widespread, systemic medications, including methotrexate or cyclosporine might be prescribed."

In addition, "A few biological agents have popped up in the past few years that you see commercials for on television and in magazines. These drugs vary from oral to injectable medications that treat the body without [requiring patients to] rub cream on each and every spot. Ultraviolet light therapy [exposure to UVA and UVB light] can be used either in medical settings or at home. For some patients, we’re also using laser therapy."

If you’re among the millions dealing with psoriasis, your best bet is to establish regular care with a dermatologist who will help you select the most effective treatment options.

Joyce Davis, MD, reviewed this article.


Joyce Davis, MD. Interview on April 8, 2015.

"Statistics." National Psoriasis Foundation. Page accessed April 8, 2015.

"Profile of Psoriasis." World Psoriasis Day. Page accessed April 13, 2015.

Brezinski, E.A., J.S. Dhillon, A.W. Armstrong. "The Economic Burden of Psoriasis in the United States: A Systematic Review." JAMA Dermatol. Published online January 7, 2015. Page accessed April 8, 2015.