Dr. Karen McKoy, Merck Manuals Editorial Board member for Dermatology, shares advice for clearing up patients’ misconceptions about sunburn and skin damage.
As temperatures rise around the country, many of your patients will spend more time outdoors in the sun. This increased exposure to ultraviolet (UV) rays, specifically wavelengths in the ultraviolet A (UVA) and ultraviolet B (UVB—280 to 320 nm) spectra, can cause serious skin damage, ranging from acute sunburn to several chronic changes—skin thickening, wrinkling, and certain lesions such as actinic keratosis and cancer, including melanoma. About 76,250 new cases of melanoma occur each year in the US, and it remains the second most common form of cancer in females age 15 to 29, according to the American Academy of Dermatology.
A recent Harris Poll conducted on behalf of the Merck Manuals found that nearly nine in ten (88 percent) Americans have had a sunburn, and many patients have misconceptions about the most effective ways to protect against the sun’s UV rays. Products make broad claims about their abilities to protect individuals from the sun, and physicians are often called on to verify or debunk these claims. With the approach of summer, now is a good time to remind your patients
Clearing up sunscreen myths
Sunscreen is an essential last layer of protection against UV rays (individuals should first limit exposure to the sun between 10 a.m. and 4 p.m. and wear tightly woven clothing and a wide-brimmed hat). But misconceptions persist about what the sun protection factor (SPF) of sunscreen actually means.
A common assumption is that SPF 30 sunscreen is twice as protective as SPF 15—in fact, nearly half (44 percent) of Americans believed this to be true. In reality, sunscreen with an SPF of 15, when applied in scientific testing environments, blocks about 93 percent of the sun’s rays. SPF 30 blocks about 97 percent. The level of protection increases only slightly above SPF 30.
In 2012, the FDA revised sunscreen testing and labeling requirements in an effort to clear up these misunderstandings. These changes included establishing a standard test to identify products that can be labeled as “Broad Spectrum”—meaning they protect against both UVA and UVB radiation. Sunscreens can be labeled as helping to prevent sunburn. But only broad spectrum products with an SPF of 15 or higher can also be labeled as decreasing the risk of skin cancer and early skin aging, “if used as directed with other sun protection measures” (a very important caveat). Sunscreen that is not broad spectrum or that has an SPF of less than 15 would come with a warning that the product has not been shown to protect against skin cancer or early skin aging. The FDA also requires sunscreen products that have SPF values higher than 50 to be labeled only as “SPF 50+” to minimize confusion about high SPF products’ effectiveness.
The Food and Drug Administration (FDA) doesn’t routinely test sunscreens; it requires the manufacturers to test their products. Unfortunately, independent testing of many products by Consumer Reports has shown they often do not live up to their SPF claims, particularly with the mineral based alone products.
Although these labeling requirements provide consumers with a better idea of how well they’re protected, the fact is many patients apply insufficient amounts to reach the levels of protection the products promise. Sunscreen should be applied at a rate of approximately two milligrams per square centimeter of skin. For the average adult, that requires applying approximately one ounce of sunscreen to exposed areas of the body. Advise your patients to think of filling a shot glass (or two tablespoons) with sunscreen when they apply it. The sunscreen should be applied 30 minutes before heading into the sun (not the minute before patients jump in the pool) and should be reapplied every two hours and more frequently after swimming or heavy sweating.
SPF clothing—worth the investment?
All clothing offers some degree of protection from UV rays, though not as much as many patients assume. In fact, 10 percent of all skin cancers occur on parts of the body that are usually covered by clothing. Not all of those instances are caused by exposure to the sun’s rays, but some are. Darker colored shirts offer more protection than white shirts, but even a dark shirt only provides a sun protection factor (SPF) of 10—much less than the SPF 30 sunscreens recommended by dermatologists. Many patients also fail to realize that wet clothing is significantly less effective than dry clothing—wearing a T-shirt in the water is an inadequate substitute for sunscreen.
Many outdoor clothing brands now offer clothes specially treated with chemical UV absorbers during manufacturing that offer an ultraviolet protection factor (UPF) of 50 and above. These articles of clothing are not regulated by the FDA, but many companies have submitted them for testing and certification by groups like the Skin Cancer Foundation.
By and large, the results of these studies have found the clothing is effective. The cost of these garments is often considerably higher than clothing without the extra protection, but most dermatologists recommend it for patients who have very light skin, are at high risk for melanoma, or know they will be exposed to the sun for unusually long periods of time.
Although various prevention methods can significantly reduce the risk of sunburn, many patients won’t take necessary precautions and will consult you only after they’ve suffered a painful sunburn. For extreme cases of severe sunburn, early treatment with a systemic corticosteroid (eg, prednisone 20 to 30 mg po bid for 4 days for adults or adolescents) may decrease the discomfort, but this use is controversial.
You should steer your patients away from topical preparations that contain anesthetics such as benzocaine and/or antihistamines such as diphenhydramine because these agents may cause secondary allergic reactions. For patients seeking symptomatic relief from less severe sunburn, you can refer them to the consumer version of the Merck Manual for discussion of safe over-the-counter options such as aloe vera or petrolatum-based products.
This survey was conducted online within the United States by Harris Poll on behalf of Merck Manuals from April 29 to May 3, 2016 among 2,015 adults ages 18 and older. This online survey is not based on a probability sample and therefore no estimate of theoretical sampling error can be calculated.