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Sunscreen Myths

The Truth About Sunscreen Will Help You Use it Correctly to Prevent Skin Cancer


Updated July 09, 2014

Sunscreen must be applied properly to be effective

Sunscreen must be applied properly to be effective

photo: Stockbyte / Getty Images
Sunscreen isn't a panacea for preventing skin cancer, but it is an easy way to reduce your risk. Unfortunately, according to a 2009 survey of 1,000 adults, almost one-third of all Americans don’t use sunscreen at all and 69% report using it only occasionally. Making matters worse is that there are many misconceptions about sunscreen that reduce its effectiveness. Here are some common myths:

The new SPF 90+ sunscreens are better than SPF 30 sunscreens.

Not much. Ultra-high SPF claims are mostly marketing gimmicks -- they don't provide an significant amount of additional protection. SPF 30 sunscreen blocks 97% of UVB rays, which is enough for most situations.

Sunscreens protect against the sun's two types of radiation: UVA and UVB.

Usually not. Manufacturers commonly make inaccurate claims about UVA protection, since the SPF rating only applies to UVB protection. The FDA is working on a new labeling standard for statements about UVA protection, but it won't be ready until 2010. In the meantime, look for products that contain avobenzone, mexoryl, titanium dioxide, or zinc oxide for adequate UVA protection.

Applying sunscreen once per day is enough.

No. Sunscreen should be applied every two hours -- even more if you're swimming or sweating a lot. Even so-called "water-resistant" sunscreens may lose their effectiveness after 40 minutes in the water.

Stored bottles of sunscreen last forever.

No. Sunscreen loses some of its effectiveness after one year, and is mostly ineffective after three years. Have leftover tubes of sunscreen from last summer? Unless they have an expiration date, toss them.

A little dab of sunscreen works just as well as a lot.

No. The recommended amount to apply is more than you might think: one ounce, or a full palmful (or shot glass). Make sure to apply it to dry skin 15 to 30 minutes before going outdoors to allow it time to be absorbed into the skin.

If it's cloudy, you don't need to worry about sunscreen.

No. Up to 80% of the sun's ultraviolet rays can pass through the clouds. In addition, sand reflects 25% of the sun's rays and snow reflects 80% of the sun's rays.

Sunscreen blocks the body's ability to make Vitamin D

One reason many people say they don’t use sunscreen is the fear of blocking vitamin D development in the body, a process that requires sun exposure. However, concerned individuals can boost their vitamin D production by taking daily supplements or eating a diet rich in fish, fortified milk, and eggs. In fact, most people get enough sun exposure just doing everyday outdoor activities, such as walking to the bus stop, even when sunscreen is applied.

Using sunscreen is enough to prevent skin cancer

No. Studies show that applying sunscreen every day can indeed reduce the formation of actinic keratoses (also called solar keratoses), which can develop into the more serious squamous cell skin cancer. However, other ways to protect yourself from the sun are even better -- and at upwards of $10 per tube, using high-quality sunscreen in the proper manner can be very expensive. So what's the alternative? Simple: just stay out of the sun in the middle of the day. If you're at the beach, use an umbrella. Minimally, wear a wide-brimmed hat and a shirt. And completely avoid tanning salons.

Over one million Americans -- both young at old -- will be diagnosed with skin cancer in 2009. Heeding these simple tips about sun safety just may save you a lot of suffering in the future.


"How Do I Protect Myself from UV Rays?" American Cancer Society. 25 May 2009.

"Facts about sunscreens." American Academy of Dermatology. 24 May 2009.

"Who's Using Sunscreen?" Consumer Reports National Research Center. 25 May 2009.

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