What Is Puva Light Therapy For?

PUVA is used to describe psoralen and ultraviolet light type A or UVA, which is found naturally in sunlight. In PUVA light therapy, psoralen, which is a prescription medication, and ultraviolet light A from a machine are used together to treat certain skin diseases. This type of light therapy is administered over a set period. It provides relief from some skin diseases but is also associated with short-term and long-term risks.

Uses

PUVA light therapy is used to treat psoriasis, vitiligo and eczema. These are all diseases that affect the skin. Vitiligo is a disease in which patches of skin lose their color or become white because they lack melanocytes, which are pigment-producing cells. In eczema, patches of skin are dry, itchy and red. Psoriasis is characterized by areas of skin that are typically thick, red and covered with scales that are silvery.

Administration

PUVA therapy is done in two stages. The first stage involves administration of psoralen. This medication is available in oral and topical forms. Psoralen can also be administered as a bath. A waiting period is required after psoralen administration. Then areas of the skin affected by conditions such as vitiligo are exposed to UVA light from a machine for a predetermined amount of time.

Mechanism

Psoralen is absorbed by all the cells in the body including skin cells. It makes these cells sensitive to UVA light. According to the National Institute of Arthritis and Musculoskeletal and Skin Diseases, psoralen and UVA light work together to repigment skin areas affected by vitiligo. Also, in psoriasis, they work to clear up signs of psoriasis by inhibiting overproduction of skin cells. An allergic reaction by the immune system can lead to eczema. PUVA therapy is effective in such cases because it prevents the allergic response that results in eczema.

Risks/Side Effects

Some common short-term side effects of PUVA therapy include redness of the skin, psoralen-induced nausea and itching. "Dermatology Nursing: A Practical Guide," by Esther Hughes and Julie Van Onselen, reports that friction blisters, painful nail discoloration and herpes simplex are uncommon short-term side effects of PUVA light therapy. Long-term side effects of this type of light therapy are skin cancer risk and early skin aging.

Precautions

PUVA therapy can cause cataracts. This happens when the eyes are exposed to UVA light after psoralen administration. The eyes should be protected once psoralen is ingested. The National Institute of Arthritis and Musculoskeletal and Skin Diseases recommends that UVA absorbing glasses should be worn one to two days after psoralen is taken.