I discovered this myself when I was about 12 years old: sunlight cleared up the rash on the insides of my elbows. More recently I’ve had itchy skin after spending too much time in chlorinated pools. Both natural sunlight and tanning beds clear up the itching for me. So I was delighted to find that phototherapy is a standard treatment for dermatitis.
Dermatitis is a general term for skin inflammation. Symptoms typically include itch, redness, and swelling. There are three main categories of dermatitis, depending on the cause:
1. Allergic contact dermatitis. The most common type is to poison ivy, poison oak and poison sumac. Other common allergens include rubber, metals, acrylates (used in artificial nails, eyeglass frames, dental resins and industrial adhesives), pine resin (used in mascara), sunscreen ingredients, hair dyes, dyes used in clothing and cosmetic ingredients.
2. Irritant dermatitis. This is similar to allergic contact dermatitis, but not a true allergic reaction. Irritants include detergents, chlorine, wool and synthetic fibers.
3. Atopic dermatitis. The cause is unknown, but genetic factors are thought to play a role. Individuals with this condition also have an increased risk of hay fever or asthma. Reference one estimates that 90 percent develop skin symptoms before age five. Atopic dermatitis is very common, affecting up to 20 percent of children. Roughly 60 percent continue to experience symptoms in adulthood. Atopic, allergic, and irritant dermatitis can all affect the same person.
The first step in treating skin rash is to work with a dermatologist to identify allergens and irritants. These should obviously be removed from the patient’s environment as efficiently as possible. However, atopic dermatitis does not have a specific environmental cause, so further treatment will be necessary in most cases.
Phototherapy provided by dermatologists uses UV light in either the A or B bands, which are reported to be equally effective. Sometimes an oral medication is used to increase the skin’s sensitivity to light. The mechanisms of UV light’s benefits are still under investigation.
A recent article reports that atopic dermatitis is characterized by an increase in the density of nerve density in the skin. UV light reduces this density, at the same time reducing the symptoms of itching. Ask your dermatologist about treatment options for any form of skin rash or itch.
Amy L. Sutton, ed., “Allergies Sourcebook”, third edition, Omnigraphics, 2007.
Majoie IM et al, “Narrowband ultraviolet B and medium-dose ultraviolet A1 are equally effective in the treatment of moderate to severe atopic dermatitis”, J Am Acad Dermatol. 2009 Jan; 60(1): 77-84.
Tominaga M et al, “Psoralen-ultraviolet A therapy alters epidermal Sema3A and NGF levels and modulates epidermal innervation in atopic dermatitis”, J Dermatol Sci. 2009 Jul; 55(1): 40-6.
By Linda Fugate PhD Linda Fugate is a scientist and writer in Austin, Texas. She has a Ph.D. in Physics and an M.S. in Macromolecular Science and Engineering. Her background includes academic and industrial research in materials science. She currently writes song lyrics and health articles.