Encyclopedia / P / Psoriasis


What Is Psoriasis?

Psoriasis is a common, persistent skin disorder, characterized by patches of raised, red bumps covered with white, flaking scales. The exact cause of psoriasis is unknown, although some research suggests psoriasis may be a type of autoimmune disorder in which the body attacks its own tissue. It generally develops on the scalp, knees, or elbows, although it may affect any area of the skin. The production of skin cells at affected sites is accelerated, either chronically or intermittently. Normally, new skin cells are constantly produced in the deepest layer of skin. From there, they rise to the top layer—the epidermis—where dead surface cells are shed, a process that typically takes about 28 days. However, in areas affected by psoriasis, new cells only take three to four days to reach the skin’s surface, and the accumulation of excess cells causes the characteristic scaly plaques.

Lesions may continue to enlarge slowly, or flare-ups of psoriasis may be separated by periods of remission.  Although most cases of psoriasis can be controlled with treatment and do not represent a serious health risk, the disorder cannot be cured and may be itchy or occasionally painful and unpleasant to live with and associated with considerable psychological distress.

Who Gets Psoriasis?

In the United States, Caucasians have a higher incidence of psoriasis; the condition affects men and women at about the same rate. An estimated 2 to 2.6% of the U.S population has psoriasis, including children. First attacks usually begin between the ages of 10 and 30. Psoriasis can run in families; When one parent is affected, there is roughly a 10% risk of a child acquiring psoriasis. The risk rises to almost 50% when both parents have psoriasis. One study analyzing psoriasis in twins found 65% of identical twin siblings had psoriasis when the other twin was affected.  Approximately 15% of psoriasis patients may subsequently develop psoriatic arthritis, a potentially debilitating joint condition.


  • Itchy or painful patches of red, raised, quarter- to dollar-size lesions, commonly located on the scalp, knees, elbows, navel, or fold of the buttocks. Lesions are round, red, and have sharply defined edges with an overlying silvery white scale. Lesions begin as small spots that progressively involve very large areas.The scales can be scraped off, resulting in pinpoint bleeding of the lesions.
  • Itching skin.
  • Loosened, pitted, thickened, and/or discolored nails. Nail involvement occurs in about 50% of psoriasis patients and can manifest as pitting on the surface, as thickening of the nail itself, or as a disassociation of the nail with the bed.
  • One form of the condition, guttate (drop-like) psoriasis, appears as a sudden eruption of numerous small, pink, scaly lesions scattered over the body. This variant typically follows a strep infection, such as strep throat. Pustular psoriasis is a distinct variant that occurs as an eruption of small pustules, or pimples, all over the body. This may be accompanied by fever. The pustules can also appear on the palms, soles, and in the nail beds.
  • Joint pain and stiffness known as psoriatic arthritis, which develops in about 5% of psoriasis patients when they are between 30 and 50 years of age. Psoriasis usually precedes the onset of arthritis by several years.
  • In rare cases psoriasis may cover the entire surface of the skin—see a dermatologist for immediate treatment.

Causes/Risk Factors

No one knows what causes psoriasis. Most people with psoriasis report that no particular event or illness preceded or brought about their condition, but several well-known triggers include stress, strep infection, and some medications. Risk factors include:

  • Family history.
  • Infection.
  • Alcohol use.
  • Smoking.
  • Stress.
  • Skin injury.
  • Cold temperatures.
  • Certain medications including antimalarial drugs, certain beta blockers and lithium, or initiation and withdrawal of intravenous or oral corticosteroids may produce a severe flare-up of total body or erythrodermic or pustular psoriasis, which are medical emergencies.
  • Psoriasis patients may be at an increased risk for complications such as metabolic syndrome and heart disease, which is associated with inflammatory conditions such as psoriasis.

What If You Do Nothing?

Without active intervention, symptoms of psoriasis can suddenly erupt or worsen. This can be physically painful and can take a toll on a person's emotional well being. And while not immediately life threatening, psoriasis that goes unmanaged may have long-term health complications, including an increased risk of heart disease. Psoriasis is not curable, but it can be controlled—and many new drugs are being developed for treating it.

** Diagnosis**

Psoriasis can be diagnosed by physical examination. To confirm the diagnosis, a skin biopsy can be obtained and sent for pathological analysis. The distinct features of psoriasis under the microscope usually confirm or exclude the diagnosis. Different skin biopsies include:

  • Shave biopsy removes the outer layer of a lesion with a sharp scalpel.
  • Punch biopsy uses a hollow, cylindrical instrument, called a punch, to remove a circular core of tissue from the center of a lesion.
  • Excisional biopsy is the removal of the entire lesion with a surgical knife.


  • Don't scratch. Scratching worsens symptoms. When using a comb or brush to care for your hair, comb gently to avoid scratching the scalp and worsening scalp psoriasis symptoms.
  • Eat a healthy diet. Certain foods can trigger psoriasis symptoms, so keep a food diary to identify any triggers, and follow a balanced, nutritious diet that includes plenty of fresh fruits and vegetables, whole grains, low-fat dairy, lean meat and fish. Be careful about alcohol consumption since this may worsen symptoms.
  • A daily bath may help treat mild symptoms. Adding a special bath solution that contains colloidal oatmeal, various oils, Epsom salts, Dead Sea salts or coal tar to the water. Blot your skin dr —don't rub—and moisturize after your bath. Preparations and shampoos containing coal tar or anthralin (a tar-like substance) may soothe irritated skin, including scalp psoriasis.
  • Moisturizing skin creams can prevent dryness, particularly when applied immediately after bathing to retain the moisture absorbed by the skin. Vitamin D-related ointmentssuch as Dovonex or Vectical are also available. A topical vitamin A-related gel called Tazorac is available. Avoid alcohol-based ointments because they can dry your skin. Many topical skin creams are used in conjunction with corticosteroids.
  • Corticosteroids, which are available in creams, ointments, gels, lotions, and foams, are the mainstay of topical therapy. They are often used for short-term management and are often used in combination with other topical therapies. Corticosteroids may cause thinning of the skin and progressive resistance and are usually discontinued gradually.

These creams contain cortisone, such as triamcinolone, fluocinolone, and fluocinonide.

vitamin D, and/or vitamin A derivatives to clear or control the psoriasis lesions.

  • Some exposure to sunlight can sometimes help with psoriasis symptoms. Physician-supervised phototherapy or photochemotherapy, or exposure to artificial ultravoilet A or B rays, can help make the skin more sensitive to other treatments. While effective for psoriasis, the ultraviolet light can increase risk of certain skin cancers.
  • Immunosuppressive or antiproliferative drugs, or other medications, may be used to clear or control the psoriasis:

o   Acitretin (Soriatane), an oral retinoid. This drug can be used alone or in combination with ultraviolet light therapy. Blood tests are performed regularly during treatment to monitor for side effects, which can include elevated levels of cholesterol and blood lipids, and liver irritation. This drug is contraindicated in women who are pregnant and in those who can become pregnant within 3 years of discontinuing treatment.

  • o Methotrexate, which inhibits cell proliferation, may be administered weekly to treat severe psoriasis and psoriatic arthritis. During treatment, daily supplementation with vitamins and 1 to 5 mg of folic acid is recommended to reduce the risk for anemia and nausea caused by the medication. Regular blood tests are also performed during treatment to detect liver inflammation. After 1–1.5 grams of the drug has been administered, a liver biopsy may be performed to detect abnormalities not apparent in blood tests.

o   Cyclosporine (Neoral) also may be used to treat psoriasis. During this treatment, kidney function and cholesterol levels are monitored using blood tests.

o   Mycophenolate mofetil is an imunosuppressant that may be used. This medication is typically less effective than other drugs, but it is safe for long-term use. Maintaining a daily dosage under 3 grams minimizes side effects such as low white blood cell count or neutropenia. Routine blood tests are performed during treatment.

o   Azathiprine is another medicine that suppresses the immune system and can help clear psoriasis.

  • o A class of medicines known as biologics are commonly used for moderate to severe psoriasis with and without arthritis.  Enbrel, Humira, Stelara, Remicade, and Cosentyx are the members of this class of medications. They are administered as an injection or IV infusion (for Remicade). These medications are used in patients who are under the care of a physician; they may be helpful for those who experience red, scaly skin over several areas of the body. Because they affect the body's immune system, they may cause serious infections, resulting from bacteria, viruses, or fungi.

o   Oral antibiotics are used in combination with standard treatments to eradicate strep infection associated with guttate psoriasis.

o   Otezla is another newer oral medication used for moderate to severe psoriasis and psoriatic arthritis.


There is no known way to prevent psoriasis. Avoiding or limiting exposure to common triggers may prevent flare-ups of psoriasis.

When To Call A Doctor

Make an appointment with a doctor if symptoms do not respond to self-treatment. Call a doctor immediately if you suddenly develop widespread psoriasis, with or without fever, joint

pain, and fatigue.

**Reviewed by Kevin Berman, M.D., Ph.D., Atlanta Center for Dermatologic Disease, Atlanta, GA. Review provided by VeriMed Healthcare Network. **