Health Topics A-Z

What Is Psoriasis?

Unpredictable and irritating, psoriasis is one of the most baffling and persistent of skin disorders. It is characterized by skin cells that multiply up to 10 times faster than normal. As underlying cells reach the skin's surface and die, their sheer volume causes raised, red patches covered with white scale. Psoriasis typically occurs on the knees, elbows, and scalp but can affect the torso, palms, and soles of the feet.

There are many forms of psoriasis — each differing in location, severity, and duration. One type, called plaque psoriasis, is the most common. About 10%-15% of people with psoriasis have associated joint inflammation that produces symptoms of arthritis called psoriatic arthritis . People who suffer from psoriasis know that this uncomfortable and at times disfiguring skin disease can be difficult and frustrating to treat. The condition comes and goes in cycles of remissions and flare-ups over a lifetime. While there are medications and other therapies that can help to clear up the patches of red, scaly, thickened skin that are the hallmark of psoriasis, there is no cure.

What Causes It?

A variety of factors — ranging from emotional stress, to trauma, dry skin, and streptococcal infection — can cause an episode of psoriasis. Recent research indicates that some abnormality in the immune system likely plays a role. As many as 80% of those having flare-ups report a recent emotional trauma, such as a new job or the death of a loved one. Many doctors believe such external stressors serve as triggers for an inherited defect in skin-cell production.

Injured skin and certain drugs — including the painkiller ibuprofen and the anti-malarial medication chloroquine — can aggravate psoriasis.

Though not contagious, psoriasis tends to run in families. Fair-skinned adults are particularly susceptible, especially those who have a blood relative suffering from the disorder. Psoriasis is extremely rare among people with dark skin.

Although psoriasis may be stressful and embarrassing, most outbreaks are relatively harmless. With appropriate treatment, symptoms generally subside within weeks.