Psoralen + UVA (PUVA)
Ultraviolet light A (UVA) is relatively ineffective for psoriasis unless it’s used with light-sensitizing agents called psoralens. This process, called PUVA, slows down excessive skin cell growth and can clear psoriasis symptoms for varying periods of time. There are three administration routes for PUVA: topically as a cream, mixed in with bathwater, or ingested orally. Stable plaque psoriasis, guttate psoriasis, and psoriasis of the palms and soles are most responsive to PUVA treatment.
Sunlight: Although both UVB and UVA are found in sunlight, UVB works best for psoriasis. UVB from the sun works the same way as UVB in phototherapy treatments.
However, using sunlight to treat psoriasis is not recommended for everyone. Sunlight is not as effective for the treatment of psoriasis as prescription phototherapy. Talk with your health care provider to find out if treating with sunlight is right for you.
Some topical medications can increase the risk of sunburn. These include tazarotene and coal tar. Individuals using these products should talk with their health care provider before going out in the sun.
People who are using PUVA (see below) or other forms of light therapy should limit or avoid exposure to natural sunlight unless directed by a health care provider.
The Risks of Tanning Beds
Some people visit tanning salons as an alternative to natural sunlight. Tanning beds in commercial salons emit mostly UVA light, not UVB. The beneficial effect for psoriasis is attributed primarily to UVB light. NPF does not support the use of indoor tanning beds as a substitute for phototherapy performed with a prescription and under a health care provider’s supervision.
The American Academy of Dermatology, the FDA and the Centers for Disease Control and Prevention all discourage the use of tanning beds and sun lamps. Indoor tanning raises the risk of melanoma by 59 percent, according to the AAD and the World Health Organization. In May 2014, the FDA reclassified sunlamps (which are used in tanning beds and booths) from Class I (low risk) to Class II (moderate risk) products.
Bottom line: The ultraviolet radiation from tanning beds and sun lamps can damage the skin, cause premature aging and increase the risk of skin cancer.