The Hot Summer Sun Isn't Only Culprit Behind Sunburn
April 24, 2011
What's going on? The answer may lie in your medicine chest. Many common drugs -- including antibiotics, antihistamines and anti-inflammatory drugs -- can act like a magnifying glass to increase your skin's photosensitivity, or vulnerability to the sun's burning rays. Common triggers include antibiotics of the tetracycline family, including doxycycline and minocycline. Likewise, sulfa drugs used to fight infection don't mix well with sun. Diuretics used to treat high blood pressure or kidney disease also can magnify sunburn. These include the thiazide family of diuretics and furosemide (sold as Lasix). Skin treatments based on retinoids -- Colton A-like compounds -- including Retin-A and the acne drug Accutane increase photosensitivity. In some people, sun sensitivity is also boosted by NSAIDs (nonsteroidal anti-inflammatory drugs) used for pain, certain antidepressants (such as tricyclics) and certain psychiatric medications (such as phenothiazines). Certain anticancer or antiseizure medications can also set you up for a burn. Just as people vary as to whether they freckle, burn or tan, individual degrees of photosensitivity differ widely from person to person. ``Photosensitivity is a conspiracy between a drug and your genetic background,'' says Paulene R. Buxton, chairman of the dermatology department at the University of Texas Southwestern Medical Center in Dallas. Differences in one person's protective pigment or ability to metabolize the drug mean they emerge unscathed while their companion gets fried. It's not only the fair-skinned who are vulnerable. DR. BERGSTRESSER points out sunlight is ``phototoxic in the first place. If you sit all day on the beach, you're going to get a sunburn, because your skin is sensitive to ultraviolet radiation.'' Ultraviolet B rays -- which make up a smaller part of the sunlight spectrum but are higher in energy -- induce most ``normal'' sunburns. Ultraviolet A light -- the greater part of the spectrum that is lower in energy -- becomes more toxic when absorbed by the drugs that trigger photosensitivity. The combination can cause redness and blistering of the skin. ``Window glass absorbs UVB but not UVA, so you can get phototoxic reactions going across country in your car. I've seen people with burns on their knuckles from gripping the steering wheel,'' he says. Phototoxic reactions result in the shiny lobsterlike redness that accompanies a severe sunburn. If you have a fever or blisters, most experts advise calling a doctor, as you would for any serious burn. Milder reactions can be treated with cold compresses and aspirin or ibuprofen (that is, provided an anti-inflammatory drug didn't trigger your reaction in the first place). A second type of photosensitivity is called a photoallergic reaction. Photoallergy happens in some individuals when the same drugs bind to a cellular protein to form a complex that arouses an immune system reaction. Instead of a sunburn, this produces an itchy, raised rash that looks more like eczema, or the raised welts of poison ivy. Whereas regular phototoxic reactions usually appear just after a day of sun, like any sunburn, photoallergic reactions can take a day longer to show up. ``One of the culprits is a fragrance called musk ambrette,'' says Dr. Buxton. ``It's an ingredient of after shave lotion.'' Affected men sometimes display a signature hand mark where they slapped scent on their cheek. Some sunscreens containing PABA esters trigger a similar allergic rash. ``You would treat photoallergic reactions like any other allergic dermatitis, with topical cortisone cream, oral prednisone, or sometimes antihistamine pills,'' says Phan Strickland, a dermatologist in private practice in San Francisco. HOW NOT TO GO for the burn? Prevention may be the best strategy. Ask your doctor or pharmacist if your medication can provoke a photosensitive reaction. The tried and true methods may help: wide-brimmed hats, broad-spectrum sunscreen blocking both UVA and UVB light and avoiding midday sun, adds Dr. Strickland. With or without drugs, people with certain medical conditions can be extremely sun-sensitive. They include folks with acne rosacea (adult acne), the autoimmune disease lupus, or xeroderma pigmentosum -- an inability to repair sun damage that affects dark and light-complexioned people alike. Worst-case photosensitivity classically afflicts the vacationer on antibiotics who travels to Mexico, Hawaii or the Caribbean, says Dr. Strickland. Handling foods such as celery, parsley, or citrus fruits can trigger sun sensitivity, too. Such was the famous case of ``Club Med dermatitis,'' reported by a physician in a letter to the New England Journal of Medicine. A well-tanned 18-year-old patient returned from a Caribbean resort with a symmetrical rash on her inner thighs. After a careful history, he identified the cause of her misery: a drinking game in which players balanced limes on their laps on the beach. A summer postscript: If you spill your margarita or your beer-and-lime, shower and reapply sunscreen before returning to the beach.
