(LifeWire) - Sunlight therapy, also called heliotherapy, has been used through the ages to help clear psoriasis patches. It is still used today and remains the cheapest and most convenient therapy for psoriasis available. Short, regular exposure to the sun - up to 20 minutes several times a week - slows the rapid turnover of skin cells that defines psoriasis, a non-contagious disease that results in thickened skin lesions, or plaques, on any part of the body.
Heliotherapy has proven so effective for psoriasis that it spawned the creation of phototherapy, a form of therapy that utilizes artificial sunlight in the comfort of a doctor's office. Phototherapy uses two forms of ultraviolet light: UVA and UVB. In the absence of much natural sunlight, such as in the winter months or in cold climates, phototherapy serves as a fine substitute.
For cost and convenience, though, it is difficult to beat the simplicity of sitting in the sunshine. Heliotherapy can either augment or replace other treatments, such as topical ointments and creams, pills, or injectable medications, known as biologics.
As with all therapies, however, heliotherapy has its risks. Not all psoriasis patients are good candidates for heliotherapy or phototherapy
Sunburn
More is not necessarily better when it comes to sun exposure, which by its very nature is unregulated and can easily be overdone. Be sure to apply a sunscreen with an SPF of 15 or higher to any skin not affected by psoriasis at least 30 minutes before sunbathing. For some people with psoriasis, sunburn (along with other skin injuries, such as cuts or insect bites) can cause the condition to flare, a response known as the Koebner phenomenon. While it does not necessarily recur with every skin injury, those who experience this response must be extra diligent to prevent sunburn when using heliotherapy. Sunblock is also important, as heliotherapy and phototherapy can accelerate skin aging.
Also, wear sunglasses that offer 100% ultraviolet light protection, since long-term UV light exposure may cause cataracts. Individuals with very fair skin and blond or red hair may want to avoid sunbathing between the hours of 10 a.m. and 2 p.m., when the sun is strongest, to reduce their usually increased risk of sunburn.
Skin Cancer
While the therapeutic benefits of sunlight for the treatment of psoriasis may outweigh the risks, it is wise to be aware of the possibility of developing skin cancer. Along with the diligent use of sunscreen, have your dermatologist do a whole-body skin exam at least once a year. Also, memorize the more common signs of skin cancer: a skin growth that changes color, size, outline, thickness or texture; or a growth that will not heal or continues to bleed, scab or crust. See your dermatologist immediately if you discover such a growth.
It is also wise to see your dermatologist before starting to self-treat your psoriasis with heliotherapy, as -- unfortunately -- skin cancer doesn't always follow the above rules of thumb.
Negative Interactions
Some medications or nutritional supplements can make skin more light-sensitive, a fact that dermatologists use to their advantage in certain forms of office-based phototherapy. These compounds include some antibiotics, oral contraceptives and high blood pressure pills, as well as herbs such as St. John's Wort and masterwort.
Other photo-sensitizing medications used specifically for psoriasis include topical tar products, calcipotriene (a vitamin D derivative), and tazarotene (a vitamin A derivative).
But that doesn't mean that all medications and treatments can be combined with heliotherapy without concern. In some cases, dermatologists recommend that patients do not combine certain treatments with heliotherapy because of the increased risk of sunburn or other negative reactions. Be sure your doctor is aware of what medications and supplements you are taking before you begin sunlight therapy.
Sources:
"The Facts About Psoriasis." HealthLink. 7 Sep. 2004. Medical College of Wisconsin. 17 May 2008. <http://healthlink.mcw.edu/article/926054522.html>.
"Sunlight and Other Psoriasis Treatments." Psoriasis.org. Oct. 2005. National Psoriasis Foundation. 13 May 2008. <http://www.psoriasis.org/treatment/psoriasis/sun/interactions.php>.
"Sunlight and Skin Cancer." Psoriasis.org. Oct. 2005. National Psoriasis Foundation. 13 May 2008. <http://www.psoriasis.org/treatment/psoriasis/sun/cancer.php>.
"Using Sunlight as a Psoriasis Treatment." Psoriasis.org. Oct. 2005. National Psoriasis Foundation. 13 May 2008. <http://www.psoriasis.org/treatment/psoriasis/sun/sunlight.php>.
