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Sunscreen: Are You Really Covered?

Our experts debunk sunscreen myths -- plus a top dermatologist reveals her favorite sunscreens.

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By Ayren Jackson-Cannady
WebMD the Magazine - Feature

Reviewed by Karyn Grossman, MD

Now that summer's in full swing, it's time to make sure you're fully protected from sun. But what kind of sunscreen should you buy? How long should you keep it? And just what are the factors for skin cancer anyway? In this special feature, we answer the top myths about sunscreen, bring you a top dermatologist's sunscreen recommendations, and offer a quick way for you to assess your own chances of getting skin cancer.

Sun-Damaged Skin: Sunburn, Melanoma and Other Reasons to Shun the Sun

Top Sunscreen Myths

1. The higher the SPF, the better the protection.

FALSE. It sounds right -- a sun protection factor of 100 should be twice as protective as SPF 50. But it's only a few percentage points more effective. An SPF of 15 screens 93% of the sun's rays and an SPF of 30 screens 97%. "But the number becomes irrelevant if you aren't applying enough in the first place," says Mona Gohara, MD, a dermatologist in Danbury, Conn., and an assistant clinical professor at Yale University Department of Dermatology. Studies show the average person slaps on one-seventh to one-tenth of the amount of SPF needed to reach the number that's on the bottle.

"For better protection apply 1 to 2 ounces (the size of a Ping-Pong ball) of sunscreen on your body 30 minutes before going outdoors [so your skin can absorb it completely], and every two hours to any exposed skin after that," Gohara says. For your face, apply a dollop the size of a silver dollar every day, no matter what the weather. Note, too, that SPF refers to protection from UVB (the burning rays) only, not UVA (the aging rays). You need to guard against both, since both can lead to skin cancer.

2. It's OK to use last year's bottle of SPF.

TRUE. Most sunscreens have a shelf life of about two years, says Jordana Gilman, MD, a New York City dermatologist. If you are using sunscreen properly, however, you shouldn't have any left, since it takes about 1 to 2 ounces of sunscreen to cover the entire body, so a 4-ounce bottle should last for only four applications.

3. Sunscreen only needs to be applied to exposed skin.

FALSE. The average T-shirt offers an SPF of about 7, notes Gilman. Darker fabrics and tighter weaves provide more protection, but it is much safer to apply sunscreen to your entire body before you get dressed. Or better yet, wear clothing made of UV protective fabrics. These have been specially treated with colorless UV-absorbing dyes, and most offer an ultraviolet protection factor (UPF) of 50, which blocks both UVA and UVB.

Don't want to invest in a whole new summer wardrobe? Spike your detergent with a wash-in SPF product you can toss in with your laundry.