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


Anyone can get psoriasis, regardless of age, but it is most likely to make its first appearance between the ages of 20 and 30 or 50 and 60. Males and females get it at about the same rate.

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

psoriasis prevalencepsoriasis prevalence

A 2005 study published in the Annals of Rheumatic Diseases found some ethnic groups, like the Japanese, have a lower rate of psoriasis than people of other ethnicities. A 2012 study published in the Journal of Investigative Dermatology showed that occurrence of psoriasis varies by geographic location, and increases as you get farther from the equator.

General Symptoms

what is psoriasis

In general, psoriasis causes patches of red, rough skin. In mild cases, it may be nothing more than patches of dry, itchy skin on the scalp. In severe cases, it can spread over large areas of the body and cause a variety of uncomfortable symptoms.

Psoriasis differs from other skin conditions in that the skin takes on the appearance of silver scales. Skin may also be dry and cracked, and has a tendency to bleed. Fingernails and toenails can become thick and pitted. If you have psoriasis, you may have occasional flare-ups followed by periods of remission.

Types of Psoriasis

There several types of psoriasis, each with its own set of signs and symptoms.

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

Scalp psoriasis: Psoriasis can also occur on the 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 nails to appear pitted and discolored. The nails can weaken and crumble, or even separate from your nail bed (onycholysis).

psoriasis types

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

Guttate psoriasis: Guttate psoriasis can be triggered by bacterial infection. It generally strikes children and young adults. Skin sores appear on the scalp, torso, arms, and legs. The scales are finer than that of other types of psoriasis. Some people have only one outbreak that clears up without treatment, but others experience additional outbreaks over time.

Inverse psoriasis: In this type of psoriasis, you’re likely to see patches of red, irritated skin in your armpits, under your breasts, or around your genitals and groin. Perspiration can make it worse. You’re more likely to get it if you’re obese. It may be triggered by fungal infection.

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. In addition to itching, pustular psoriasis can cause fever, chills, and diarrhea. Blisters may clear up and return periodically. Flare-ups may be triggered by infection, irritation, or even by some medications.

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

Cause and Risk Factors

psoriasis causes

The exact cause of psoriasis remains unknown, but it involves an immune system response. In your immune system, it’s the job of your T-cells to attack foreign organisms and 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. The build-up occurs too quickly, allowing dead skin cells accumulate. This creates the hallmark scaly patches.

According to the Cleveland Clinic, genetics may play a role. You’re more likely to develop psoriasis if one of your parents has it. That risk is increased if both 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. So are children who have frequent bouts of strep throat or other recurring infections. Because psoriasis often begins in the folds of skin, you’re at greater risk if you’re overweight or obese.

psoriasis risk factorspsoriasis risk factors

Smokers have a higher risk of developing psoriasis. If you already have the condition, smoking may make it worse. Flare-ups may be influenced by stress or triggered by certain medications, including beta-blockers, interferon, and lithium.

You don’t have to fear being around someone with psoriasis. No type of psoriasis is contagious.

Tests and Diagnosis

psoriasis 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 three million office and hospital visits a year, 80 percent of which are managed by dermatologists (doctors who specialize in treating skin conditions).

In many cases, a diagnosis can be made on physical examination and medical history. If there’s any doubt, a biopsy may be ordered to confirm the diagnosis.


There is no cure for psoriasis. The main objective of treatment is to slow down growth of skin cells and to relieve pain and itching.

For mild cases, there are a variety of over-the-counter topical ointments that can help. Prescription corticosteroids have anti-inflammatory properties and slow cell growth and relieve itching. Special solutions are formulated for use on the scalp. Corticosteroids are generally used only during flare-ups. Other topical treatments include:

  • calcipotriene (Dovonex), calcitriol (Rocaltrol): synthetic vitamin D to slow growth of skin cells
  • anthralin (Dritho-Scalp): medication to regulate DNA activity in skin cells and remove scales
  • tazarotene (Tazorac, Avage): vitamin A derivative to normalize DNA activity and decrease inflammation
  • tacrolimus (Prograf), pimecrolimus (Elidel): calcineurin inhibitors to reduce inflammation
  • salicylic acid to get rid of dead skin cells
  • coal tar to reduce inflammation and scaling
  • moisturizers to sooth dry skin

psoriasis treatmentspsoriasis treatments

Various forms of light therapy can also be effective. So can natural sunlight, because light can slow skin cell growth and scaling.

Other treatment options are oral and injectable drugs, including retinoids, methotrexate, and cyclosporine. Severe psoriasis may also be treated with biologics, which are medications designed to alter your immune system.

The AAD estimates that in the United States, the cost of treating psoriasis reached $1.2 billion in 2004.


Having any form of psoriasis increases your risk of developing psoriatic arthritis.

Psoriasis may also increase your risk of metabolic diseases, high blood pressure, and cardiovascular disease. According to the AAD, if you’re in your 40s, a mild case of psoriasis raises your risk of heart attack by 20 percent. Severe psoriasis can double your risk.

You may also be higher risk of type 2 diabetes, kidney disease, and Parkinson’s disease, as well as other autoimmune disorders like Crohn’s disease and celiac disease. Psoriasis can increase your chances of developing eye problems like conjunctivitis, uveitis, and blepharitis.

psoriasis complicationspsoriasis complications

Frequent bouts of psoriasis can cause you to withdraw from social situations or work, and may lead to feelings of depression. In severe cases, quality of life can suffer.

Because of the potential for complications, people with psoriasis should have regular physical examinations and screenings for related conditions.


A variety of skin conditions look similar to psoriasis, so it’s worth having your doctor examine any skin rashes that don’t clear up. Among the look-alikes are:

Ringworm: It has the same red, scaly look of psoriasis, but ringworm is caused by a fungal infection. Ringworm usually clears up within a few weeks.

Seborrheic dermatitis: It looks a lot like psoriasis and usually forms on the scalp, face, upper chest, or back. It may recur, but it doesn’t affect your general health.

Lichen planus: It causes lesions on your limbs, on your genitals, or inside your mouth. It can last a long time and may recur.

Pityriasis rosea: It’s a raised rash that often begins as one big spot. It usually clears up within eight weeks.