9 surprising facts about sunscreen

Sunscreen is a must.
You need sunscreen: no ifs, ands or buts about it. Melanoma is the deadliest form of skin cancer, and using sunscreen daily is your best defense against it, according to the American Academy of Dermatology. More than 73,000 Americans are expected to be diagnosed with melanoma this year. "But I wear sunscreen pretty often," you might think, "I'm sure I'm fine!" Chances are, you're not fine. Here are surprising facts about sunscreen your dermatologist wishes you knew.

1. SPF doesn't block it all.
SPF only provides protection against UVB rays – the ones that leave you burnt and crispy. "There's a whole spectrum of UVA people should protect [against] as well," says Dr. Joel Cohen, spokesman for the American Academy of Dermatology and director of Aboutskin Dermatology and Derm Surgery, a private practice in Englewood, Colorado. These rays are much wider and penetrate the skin more deeply, he says, "causing lines, wrinkles, pigmentation [changes], laxity and skin cancer." That's why the Food and Drug Administration and other groups want consumers to find sunscreens labeled "broad spectrum," indicating protection against both types of harmful rays.

2. Remember the shot glass rule.
If you found a bottle of sunscreen in your cabinet left over from last year or even six months ago, you're probably not using enough of it. "I tell people that they should apply a marble-sized amount for their face, ears and neck, and a golf-ball size (or shot-glass size) for the full body. For people who are biking and sweating a lot, I always have them do two applications," Cohen says. Aim for 2 ounces in each application to achieve this shot-glass rule. Most bottles contain 8.

3. Tend to the forgotten skin.
The lips, ears, hairline, neck, feet and hands are often dismissed when it comes to sun protection, says Dr. Rachel Herschenfeld, a dermatologist at Dermatology Partners in Wellesley, Massachusetts, and an AAD fellow. "People may not love putting it on the hairline because it can get the hair greasy, but you probably need a shower after a day at the beach anyway," she says. If you're sporting sandals or flip-flops, don't forget to put sunscreen on your feet. For your lips, get a balm containing titanium dioxide and zinc, which block the sun's harmful rays.

4. Tattoos aren't a barrier.
If you've got a red or yellow tattoo, this is for you. "Many people don't think they need sunscreen for many reasons. For instance, if they have a tattoo," says Dr. Debra Jaliman, a New York City-based dermatologist and author of "Skin Rules." "But if anything, it will make you more sun-sensitive or offer no protection at all." Yellow and red inks contain a chemical called cadmium sulfide, which can cause rashes or scaly, flaky skin when it's allowed to bake in the sun.

5. The scalp is vulnerable.
If you part your hair, you're exposing a sensitive area of skin. If you can't or choose not to wear a hat, try a scalp sunscreen product. They're not greasy, and they actually nourish your hair, Jaliman says. If you're bald or balding, any broad-spectrum spray or cream sunscreen will do.

6. Scars need sunscreen, too.
All scars should be covered with broad-spectrum sunscreen that's at least SPF 35 at all times, Cohen says. Not only do you run the risk of hyperpigmentation – discoloration or darkening of the skin – but skin cancer is also more likely in those spots because the skin is already damaged.

7. The sun's rays don't discriminate.
No matter the color of your skin, sunscreen should be used by all. African-Americans have more melanin – what gives skin, hair and eyes their color – which can provide an SPF equivalent of 4 or 6, Jaliman says. Still, the AAD recommends an SPF of at least 30. "If you're any color, you can still get melanoma," Jaliman explains. "African-Americans are often diagnosed later, so they have a higher death rate from melanoma compared with Caucasians because nobody looks for them."

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