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Sunscreen: How to Wear It

  • Dana Sullivan
  • Posted March 11, 2013

Do I have to wear sunscreen every day?

You do, if you spend time outside and don't want to end up looking like a prune. Every day you go unprotected now may mean another tiny wrinkle later. Most sunscreens these days shield you from both ultraviolet A and B radiation. While UVB rays are the ones that cause sunburn, UVA rays penetrate deep into the base layer of the skin, where they break down the proteins that keep skin firm and young-looking. (Both kinds of UV contribute to skin cancer.)

UVA rays are the ones that lead to wrinkles and age spots and they beat down on you from dawn to dusk every day of the year, even when you're in the car or indoors, since they can penetrate glass. One good solution is to use a daily moisturizer with sunscreen on exposed areas like your face and hands. But be sure to slather it on; you'll need about a teaspoon to cover your face adequately. And reapply if you're going outside for lunch.

But didn't they prove that sunscreen doesn't protect against cancer?

You may have heard about an old report that suggested sunscreen may not help you avoid melanoma, the deadliest form of skin cancer. The controversial report also implied that sunscreen use might actually increase the risk of skin cancer because it staves off sunburn, thus allowing you to spend more time in the sun than you otherwise would. But critics point out that the study focused on sunscreens that defended skin from UVB radiation only. In addition, more recent research from Australian has shown that regular use of sunscreen does reduce the risk of melanoma. For these reasons, dermatologists recommend that you wear a so-called broad-spectrum sunscreen -- that is, one that blocks both A and B rays -- every day.

Are all broad-spectrum sunscreens equally effective?

They're all pretty good at screening UVB rays, but blocking UVA is a little trickier. The most effective sunblocks contain zinc oxide or titanium dioxide. Unlike chemical sunscreens that sink into the skin and absorb radiation as it hits, these ingredients sit on top of your skin, forming an almost invisible physical barrier against UV rays. All sun protection products will lose their effectiveness after a while, so check the expiration date before using them. If you have any doubts about how old the tube is, buy a new one.

What SPF should I choose?

That depends on your coloring and the amount of time you'll be in the sun. When using a sunscreen with a Sun Protection Factor of 15, you'll get the equivalent of one minute of burning UVB rays for every 15 minutes you spend in the sun. If you're an olive-skinned brunette, that'll buy you about five hours in the sun before you're visibly burned, while the fair and freckled may get only two and a half. SPF 15 blocks about 93 percent of UVB rays, which is enough protection for most people on most days, but a blonde on a sunny beach should use SPF 30, which blocks 97 percent of UVB.

How much do I have to use?

If you don't feel as though you're overdoing it, you probably aren't using enough. You need at least a shot glass-full (or two tablespoons) to cover your entire body. That's about one ounce or a quarter of an average-size tube. Most people use about half that much and thus get half as much protection as they think they're getting. Be especially careful to coat your nose, ears, neck, shoulders, and the tops of your feet. And smear on a lip balm with sunscreen as well. If you're running around in a bathing suit, a spray-on sunscreen may be useful for frequent applications. But you should probably have someone else do your back to be sure it's completely covered. And don't wait until you get to the beach to start the process. Your skin needs at least 20 minutes to absorb the sunscreen's chemicals.

Do the waterproof versions really work?

"Waterproof" sunscreens are supposed to protect you for 80 minutes whether you're in the water or not ("water resistant" ones should work for 40 minutes). But the government prohibits sunscreen makers from using terms like "waterproof" or "all-day protection" because there's not enough evidence to support those claims. And as with any other sunscreen, you're likely to rub the lotion off as you move around, wipe the sweat from your brow, or dry yourself with a towel. So reapply every hour or so, even if you're just sitting there -- more often if you're swimming or sweating it out on the tennis court.

Is wearing sunscreen enough to protect me?

That depends on your complexion and how much time you spend in the sun. If you are fair-skinned and need to spend considerable amounts of time in the sun, you'll probably need to take some increased precautions. Try wearing protective clothing like a broad-brimmed hat, long-sleeved shirt, long pants and sunglasses. Also, try to lessen your exposure to the strongest midday sun between 10 a.m. and 4 p.m.

What about vitamin D?

Sunscreen block vitamin D synthesis in the skin. For this reason, if you cover up, wear sunscreen and generally avoid the sun, be sure to get enough sources of vitamin D in your diet, such as eggs, salmon and fortified milk, and check with your doctor about taking a vitamin D supplement. (Some physicians recommend 2,000 IU daily.) In addition, some doctors recommend getting at least 5-10 minutes of early morning or late afternoon sun "unprotected" to increase the body's vitamin D synthesis.

How about claims that sunscreens don't work?

The Environmental Working Group recently criticized some chemicals used in sunscreens, but the group still advocates using an effective sunscreen, as well as seeking out shade in peak hours and wearing protective clothing.

What else is new with sunscreens?

Researchers are investigating the systemic absorption of various chemicals in sunscreen and how that may affect different groups, including pregnant women and children.

References

EWGs 2010 Sunscreen Guide. Environmental Working Group, 2010.

Storing Enough Vitamin D? Dr. Andrew Weil online. June 6, 2008

Food and Drug Administration. Questions and Answers on the 2007 Sunscreen Proposed Rule. August 2007.

Berg, Alfred O: Counseling to Prevent Skin Cancer: Recommendations and Rationale of the U.S. Preventive Services Task Force. Mortality and Morbidity Weekly Report. October 17, 2003: 52(RR15); 13-17.

Berwick, Marianne. Sunscreen and skin cancer: What's happening? American Association for the Advancement of Science. 1998, February 17.

Donawho C, Wolf P: Sunburn, sunscreen, and melanoma. Curr Opin Oncol 1996;8:159-166.

Garland CF, Garland FC. Gorham ED: Rising trends in melanoma: A hypothesis concerning sunscreen effectiveness. Ann Epidemiol 1993:3:103-110.

Ferrini RL, Perlman M, Hill L: American College of Preventive Medicine policy statement: Screening for skin cancer. Am J Prev Med 1998;14:80-82.

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