What Is Psoriasis?

Psoriasis is a common skin condition characterized by a rapid buildup of rough, dry, dead skin cells forming thick scales. The inflammation can be frustrating if you have it, causing unsightly patches of skin, discomfort and even pain.

Normally, it takes about a month for new skin cells to move from the lowest layer of your skin, where they form, to the outermost layer, where they die and scale off in flakes. In psoriasis, the life cycle of skin cells speeds up, resulting in a multitude of dead cells on the outermost layer of your skin.

Psoriasis is a persistent, chronic disease that tends to flare for weeks or months, then may go into remission. It affects about 5.5 million Americans, and 1.5 million Americans see their doctors each year for psoriasis. Psoriasis can occur suddenly at any age, but the onset is usually gradual and begins between ages 15 and 35.

Signs and Symptoms

Signs and symptoms of psoriasis may include:

• Dry, red patches of skin covered with silvery scales
  
  
• Small scaling dots (most common in children)
  
  
• Swollen and stiff joints

The signs and symptoms may occur in just a few spots on your skin or affect large areas. Psoriasis commonly occurs on your knees, elbows, trunk and scalp. The scales from scalp patches of psoriasis may resemble dandruff. In severe cases, you may also experience cracked skin, itching, minor bleeding and raised bumps containing pus on your skin. In some cases, there may be pitting, ridging and discoloration of fingernails and toenails.

Psoriasis isn't contagious. You can't spread it to other parts of your body, or to other people, simply by touching it.

The condition typically goes through cycles. It may flare for weeks or months, then subside for a time with no symptoms. But it almost always returns. Psoriasis can occur anywhere on your body. It's possible to confuse psoriasis with seborrheic dermatitis, a different common skin condition that's characterized by greasy-appearing, scaling areas.

Arthritis accompanies psoriasis in about 1 in 10 people. For most, the effects of psoriatic arthritis are minor. It produces some pain and discomfort in affected joints but has little effect on overall health. Less commonly, the joint symptoms can lead to significant disability similar to that found sometimes in rheumatoid arthritis.

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Causes

If you cut yourself, the skin heals by regenerating the top layers. When the wound is healed, the process stops. But with psoriasis, skin cells continue to proliferate. This usually doesn't stop unless treatment interrupts the cycle.

Factors that may trigger this exaggerated wound-healing process of psoriasis include:

• Systemic infection such as strep throat.
  
  
• Immune system response to disease.
  
  
• Injury to your skin.
  
  
• Reaction to a medication or vaccine.
  
  
• Stress.
  
  
• Alcohol. The poor nutrition that may accompany heavy drinking may make psoriasis worse.
  
  
• Environmental factors, such as exposure to sun or to chemicals such as disinfectants and paint thinners.

Doctors believe psoriasis to be an inherited disease, influenced by many factors. But researchers haven't yet been able to identify the gene or genes responsible for psoriasis.

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When to Seek Medical Advice

For most people, psoriasis is a mild nuisance. For others, it can be almost totally disabling. If your skin condition moves beyond the nuisance stage and causes you discomfort and pain, if it makes performing routine tasks difficult, or if you're concerned about the appearance of your skin, talk to your doctor.

Treatment

One of the things that make psoriasis so difficult to control is its wide variation in type, severity and response to treatment. Because each case of psoriasis is unique, your doctor will tailor a treatment to you. The goal of treatment is to suppress the growth of your skin cells. Among the treatment approaches:

• Creams and ointments. Calcipotriene (Dovonex) is an ointment available by prescription that contains a derivative of vitamin D. Calcipotriene controls the overproduction of skin cells. It's a useful treatment for mild to moderate psoriasis. Steroid creams, coal tar, anthralin and a recently available topical form of retinoic acid are other topical treatments.
  
  
• Oral medications. Retinoids are a group of drugs related to vitamin A. Retinoids reduce the proliferation of skin cells in cases of severe psoriasis. They can produce side effects such as eye and lip inflammation, bone spurs and hair loss, as well as birth defects if you take them during pregnancy. Other oral medications include methotrexate, an anticancer drug that blocks the growth of skin cells in psoriasis, and cyclosporine (Gengraf, Neoral), which suppresses your immune system and is an antirejection drug used in organ transplants. Though these drugs are effective in treating severe psoriasis, they may also cause side effects, including liver and kidney toxicity.
  
  
• Phototherapy. Psoralen ultraviolet A (PUVA), a combination of light-sensitizing medications (psoralens) and ultraviolet A light, is effective in suppressing the growth of skin cells in severe psoriasis. However, long-term — 250 treatments or more — use of PUVA may increase your risk of melanoma, a deadly form of skin cancer. The higher risk begins about 15 years after the first PUVA treatment. Exposure to moderate sunlight — being careful to avoid sunburn — as well as the topical application of coal tar combined with ultraviolet radiation also are effective treatments. A form of phototherapy treatment called narrow-band ultraviolet B (UVB) has emerged in the past decade. This treatment may be as effective as PUVA but doesn't require that you take oral medications before each treatment. It's not suspected to carry as high a potential for skin cancer as PUVA.

Topical treatments and phototherapy often are combined to increase their effectiveness. Doctors sometimes use phototherapy and oral medications in rotation to minimize side effects of both.

Self-Care

These steps may help improve symptoms of psoriasis:

• Eat a nutritionally balanced diet, get adequate rest and exercise regularly.
  
  
• Maintain a healthy weight. Psoriasis often occurs in skin creases or folds.
  
  
• Avoid scratching, rubbing or picking at patches of psoriasis.
  
  
• Bathe daily to soak off the scales. Avoid hot water or harsh soap.
  
  
• Keep your skin moist. Pat rather than rub dry after bathing, apply a heavy, water-in-oil moisturizing cream immediately after bathing while your skin is still moist, avoid creams or lotions containing alcohol, and use a humidifier and keep room temperatures cool.
  
  
• Use soaps, shampoos, cleansers or ointments containing coal tar or salicylic acid.
  
  
• Expose your skin to moderate sunlight, but avoid sunburn.
  
  
• Apply over-the-counter cortisone creams, 0.5 percent or 1 percent, for a few weeks when symptoms are especially bad.

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— July 1, 2001 —