Psoriasis is a condition that affects the skin. It happens when the immune system stimulates over production of new skin cells. Plaque psoriasis is the most common form of psoriasis and its symptoms typically include thick patches of skin that are red and covered with silvery scales--also called plaque. Sunlight is made of ultraviolet A, or UVA, and ultraviolet B, or UVB, light. PUVA therapy involves the use of a medication called psoralen and ultraviolet A light--from a device--to treat psoriasis.
Indication
PUVA therapy is used in cases where topical treatments such as creams and ointments have failed to work on areas affected by plaque psoriasis. It is also used to treat generalized plaque psoriasis. Additionally, the National Institute of Arthritis and Musculoskeletal and Skin Diseases states that PUVA therapy is used when more than 10 percent of the body is affected by psoriasis or when a person's job is affected by this disease. PUVA therapy is also used to treat small patches of pustular psoriasis on the soles of the feet and the palms of the hands. Though not usually done, it can also be used to treat guttate psoriasis.
Administration
PUVA therapy is a two-step process. First, oral or topical psoralen is given to the patient. Instead of oral or topical psoralen, patients can take a psoralen solution bath before UVA treatment. Psoralen makes the skin more sensitive to UVA light. There is a brief waiting period after psoralen administration--usually between 10 minutes to two hours, after which a specific dose of UVA light is directed at skin affected by psoriasis.
Time Frame
The University of Maryland Medical Center explains that UVA light treatments start with short exposure times--a few seconds or minutes. Then the treatment time is gradually increased up to 20 minutes or longer. An average of 25 treatments given over a period of two to three months is required for psoriasis symptoms to clear up. The treatment is done about two to three times a week. After PUVA treatment, some patient's psoriasis remains cleared up for a long time. Patients with more aggressive psoriasis require maintenance treatments once or twice a month.
How It Works
UVA light in conjunction with psoralen inhibits excessive production of new skin cells seen in psoriasis. It does this when it blocks the DNA synthesis process that causes overproduction of new skin cells.
Risks/Side Effects
Some of the short term side effects associated with PUVA treatment for psoriasis are redness of the skin; itching; and nausea, caused by psoralen. Long term side effects include an increased risk for skin cancer and early aging of the skin as evidenced by thin, dry, wrinkly skin and development of age spots--brown spots seen on the skin.
