The 15 biggest sunscreen mistakes

Common ways you're screwing up sunscreen, and how to truly protect yourself from the sun.
Health.com // Health.com

SPF smarts

By now, you probably know that you should use sunscreen every day both to help reduce your risk of skin cancer and to prevent pesky wrinkles, dark spots, and other signs of premature aging. Yet even people who do slather it on religiously make potentially dangerous mistakes. Here are the most common ways you're messing up with sunscreen—and how to truly protect yourself from UV rays.

--By Sarah Z. Wexler, Health magazine 

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You wait until you're outside to apply sunscreen

How many people have you seen get to the beach, spread out their blankets, strip down to their swimsuits, and then start slathering away? "You actually want to apply your sunscreen 30 minutes prior to exposure," says Jeannette Graf, MD, assistant clinical professor of dermatology at Mount Sinai Medical Center in New York. That way, it has time to get absorbed and start working—and so you don't get UV exposure for those first few minutes when your skin is vulnerable.

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You apply sunscreen around your clothes

Skin cancer can strike anywhere, so it's best to apply sunscreen when you're buck naked. Otherwise, "if you already have a swimsuit or clothing on, you're likely to apply it gingerly so you don't get it on your clothes, which makes you likely to miss a spot or not apply liberally enough," says Noelle Sherber, MD, a consulting dermatologist for the Johns Hopkins Scleroderma Center. Strip down in front of a full-length mirror, she says, which "helps ensure you entirely cover tricky spots like the mid-back and backs of the legs." (And you should apply before going outside anyway, right?)

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You don't protect your lips

Just like the rest of your skin, lips are vulnerable to UV rays, so it's extremely important to use sunscreen on your mouth, Dr. Graf says. But don't use the same stuff you use on the rest of your body—it tastes weird and won't last that long on your lips anyway. So try a lip balm with SPF, which is thicker so it stays on longer. "Then reapply even more frequently than you do body sunscreen, since talking, eating, and drinking removes the sunscreen on your lips faster," she says.

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You miss other key spots

Think you can smear sunscreen on your nose like a 1950s lifeguard and be covered? Unfortunately, there are lot of less-obvious areas people tend to forget—and they're just as important to protect, Dr. Graf says. "The most commonly missed areas are toes and feet, including the bottoms of your feet; underarms; back of the neck under the hairline; ears, especially the tops and back of your ears; eyelids; and inner upper arms." Put that stuff everywhere.

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You sweat (or rinse) it all off

The small print on your sunscreen label matters, so make sure you're choosing the right sunscreen for your activity, especially if that activity involves sweat, a pool, or the ocean. "Make sure you get a water-resistant formulation for swimming or activities where you'll perspire, because non-water-resistant formulas can slide right off," says Dr. Sherber. "Plus, they tend to mention migrate into eyes and sting, whereas water-resistant ones won't."

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You use a body formula on your face

It's not just a marketing gimmick: There is a difference between face- and body-specific sunscreens. "Facial skin is generally more sensitive to irritation than body skin, so face formulations have been tested to cause less irritation and not trigger acne," says Dr. Sherber. "If you're acne-prone or sensitive, avoid the body versions for your face, especially the dry-touch sprays—they're absolutely full of alcohol, which is very drying and irritating for facial skin."

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You only use it when it's nice out

Danger! It may seem counterintuitive to slather on sunscreen on a gray or drizzly day, but you can get UV exposure without ever seeing the sun in the sky, says Dr. Graf. Eighty percent of UV rays still come through on cloudy days, according to the American Academy of Dermatology, so don't let the weather affect your sunscreen use.

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You don't use enough

The old rule about using a shot glass worth of sunscreen every time you apply still holds up, says Dr. Graf. (That's about 1.5 ounces.) But now that more of us are opting for continuous spray formulas, it can be hard to tell if we're really getting enough coverage. To make sure you're using sprays correctly, she suggests holding the can six inches from skin and spraying nonstop, so you can see the moisture covering the entire area. "Then rub it in—yes, even if the bottle says you don't have to—so you don't miss spots," Dr. Graf says. "And repeat the spray a second time."

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You think you're safe indoors or in cars

Unless you choose to spend your time in a windowless bunker, you're not protected from UV rays when you're inside. "Driving can be a major source of incidental exposure," says Dr. Sherber. "The windows and windshield block UVB rays so you don't see a sunburn, but UVA seeps right in, and that's the spectrum that causes most skin aging and skin cancer." Your best bet: apply sunscreen every morning, then feel free to sit by a window or take a drive! At the very least, try a moisturizer with SPF so you're not adding a step to your daily routine.

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