A Sensitive Subject: Defining Photosensitivity

by Scott Eric Barrett

Two French celebrities can be credited with the transformation from pale to tan. In the 1920s, as fashions freed women from confining clothes, designer Coco Chanel inadvertently gave the fashion world another new trend: while cruising from Paris to Cannes aboard the Duke of Westminster's yacht, she obtained a suntan. Around the same time, Parisians fell in love with caramel-skinned singer Josephine Baker. Emulating these two French idols, fashionable women everywhere threw away years of pale tradition to be tanned.

By the 1940s, women's magazines encouraged suntanning, and cosmetics companies began to introduce sun-tanning oils.

With nearly 30 million Americans actively tanning indoors, and millions more soaking up outside rays, photosensitivity has become a topic of discussion. Many of you have turned to your professional tanning salon operators for advice about curbing your chances of experiencing photosensitivity, which is an allergic reaction caused by certain foods, cosmetics or drugs when combined with UV exposure.

The list of photoreactive agents is long, but the degree of photosensitivity varies among individuals. Not everyone who uses medications or products containing photoreactive agents will have a photoreaction.

Awareness Is The Key

Science caught on in the 1960s when European scientists pioneered photosensitivity disorder research. In 1967, Danish researchers blamed perfumed soap for an outbreak of strange skin lesions. In 1969, British researchers discovered that sandalwood oil in sunscreens and facial cosmetics caused photoallergies. The group also reported that quindoxin, a food additive in animal feed, caused phototoxic erythemal skin patches on British farmers who handled the feed.

Shortly thereafter, French scientists demonstrated that bergamot oil in sunscreens caused photosensitivity disorders and German researchers isolated photoreactive agents in colognes, perfumes and oral contraceptives.

In 1972, American scientists linked sunlight-activated aniline compounds (found in drugs, varnishes, perfumes, shoe polish and vulcanized rubber) to hives and skin conditions such as dermatitis and dandruff.

Thanks to all the research, scientists know there are two main reactions with photosensitivity. Phototoxic reactions occur when the sun's ultraviolet rays activate chemicals in food, cosmetics or medications. Photoallergic reactions occur when the sun's ultraviolet rays trigger an immune system response to medications.

The symptoms of these two types of reactions vary. Phototoxic reactions resemble a bad sunburn on areas of the skin that are directly exposed to sunlight. They occur anywhere from 30 minutes to several hours after exposure. The reaction also may include erythema, pain and possibly blisters. Photoallergic reactions manifest as scaly, itchy rashes that can appear anywhere from one to 14 days after exposure on exposed areas of the skin, as well as other parts of the body.

In his study, "Chemical Photosensitivity: Another Reason to Be Careful in the Sun," Craig D. Reid, Ph.D., says photoreactive agents may enter the skin several ways--orally, topically or parenterally--but must be present when the skin is exposed to UVR. Compounds that cause photosensitivity usually are cosmetic or therapeutic in nature. After exposure to UV radiation from natural sunlight or an artificial source such as tanning lamps--or even those purple-lighted mosquito zappers--photoreactive agents cause chemical changes that increase a person's sensitivity to light, causing the person to become photosensitized. When this happens, characteristics can include an exaggerated sunburn-like skin condition, hives, abnormal reddening of the skin or eczema-like rashes with itching, swelling, blistering and scaling of the skin.

Widely used medications containing photoreactive agents include antihistamines, which are used in cold and allergy medicines; nonsteroidal anti-inflammatory drugs, used to control pain and inflammation in arthritis; and antibiotics, including tetracyclines and sulfonamides, or "sulfa" drugs.

Other photoreactive medications include but are not limited to water pills (diuretics) birth-control pills and some high-blood-pressure medications. FDA also has reported photoreactive agents have been found in deodorants, antibacterial soaps, artificial sweeteners, fluorescent brightening agents for cellulose, nylon and wool fibers, naphthalene (mothballs), petroleum products, and in cadmium sulfide, a chemical injected into the skin during tattooing. (For a more detailed list of photoactive agents, see page 30.)

Potential Vitamin Solutions

Conventional treatment of photosensitivity includes the avoidance of direct sunlight and the use of sunscreen. In addition, doctors may prescribe beta-carotene or hydroxychloroquine to reduce the severity of reactions. Oral corticosteroids are often prescribed to clear up the skin rash once it appears.

According to the Journal of the American Medical Association, large amounts of beta-carotene (up to 150,000 IUs per day for at least several months) have allowed people with photosensitivities to stay out in the sun several times longer than they otherwise could tolerate. The protective effect appears to result from beta-carotene's ability to protect against free-radical damage caused by sunlight.

Less is known about the effects of other antioxidants. Research with vitamin E has been limited and has not yielded consistent results. Cases have been reported of people with photosensitivities who respond to vitamin B6 supplements. Amounts of vitamin B6 used to successfully reduce reactions to sunlight have varied considerably. Some nutritionally oriented doctors suggest a trial of 100 to 200 milligrams per day for three months. Niacinamide, a form of vitamin B3, can reduce the formation of a kynurenic acid--a substance that has been linked to photosensitivities. One trial studied the effects of niacinamide in people who had polymorphous light eruption, one of the photosensitivity diseases. Taking one gram three times per day, most people remained free of problems despite exposure to the sun.

Knowledge is the best way to avoid this uncomfortable skin condition. All professional salons are required to post complete lists of all the medications, topical solutions and foods that have been known to incite a photoreaction.

When Herbs And Sunlight Don't Mix

At least one of every 20 Americans gets depressed each year. Many people, from the time of ancient Greece through the Middle Ages, believed St. John's wort could alleviate symptoms of depression. In Europe, St. John's wort has a long history of use, particularly as a folk remedy in the treatment of wounds, kidney and lung ailments.

The major components in extracts of St. John's wort include flavonoids, kaempferol, luteolin, biapigenin, hyperforin, polycyclic phenols, hypericin, and pseudohypericin. Researchers believe the last three substances are the active ingredients. New research suggests that hyperforin also may play a large role in the herb's antidepressant effects. From this research it appears St. John's wort will continue to be a highly respected herb for many years to come.

The herb seems like a perfect complement to UVR since light therapy has been suggested to elevate a person's mood too. Unfortunately, this cure-all herb has been shown to cause sensitivity to UVR. St. John's wort can cause severe photosensitivity in animals grazing extensively on the plant.

The term hypericism describes a skin disease found in animals that graze on large quantities of St. John's wort. However, reports of photosensitivity in humans are rare and have been limited to those taking excessive quantities for HIV infection. St. John's wort is unlikely to be toxic to humans when used at recommended medicinal doses.

Dr. Donald Brown of Kenmore, Wash.-based Bastyr University recommends that persons with fair skin avoid exposure to strong sunlight and other sources of ultraviolet light when taking St. John's wort because of some reported cases of photosensitivity. He also advises avoiding foods that contain tyramine, alcoholic beverages and medications such as narcotics, amphetamines and over-the-counter cold and flu remedies while taking St. John's wort. Persons taking the herb should apply a sunscreen (SPF 15 or higher) prior to exposure to direct sunlight and limit the duration of exposure.

Besides St. John's wort, bitter orange peel, celery, dong quai, motherwort, parsley, peppermint oil and wormwood also can cause photosensitivity in certain individuals.