Get the Most Out of Your Sunscreen

Last Editorial Review: 1/31/2005

You have to maximize sun protection to minimize skin cancer risk.

By Jennifer Warner
WebMD Feature

Reviewed By Michael Smith

Remember when baby oil was as common at the beach as bikinis? Now the average beachcomber is more likely to have an arsenal of sunscreens with various sun protection factors (SPFs) ranging from 15 to 50 to block the sun's damaging rays and reduce the risk of skin cancer.

But unless used properly, you may be getting only a fraction of the sun protection promised on the sunscreen's label.

Experts say many people may be operating under a false sense of security when it comes to sunscreen. Dermatologist Martin Weinstock, MD, PhD, says the truth is that most people don't put on enough sunscreen, don't put it on at least 20 minutes before going out in the sun, and don't reapply it often enough.

Weinstock is the chairman of the skin cancer advisory group at the American Cancer Society and advocates a "Slip! Slop! Slap! Wrap!" approach to protecting your skin from the sun. That catch phrase reminds children as well as adults to slip on a shirt, slop on sunscreen, slap on a hat, and wrap on sunglasses to protect your eyes and skin from ultraviolet (UV) exposure. Slip! Slop! Slap! Wrap! is a trademark of the American Cancer Society.

When it comes to slopping on sunscreen, Weinstock says one thin coat is just not enough. In addition to applying one coat of sunscreen about 20 minutes before going out into the sun, he recommends applying a second coat of sunscreen 20 minutes after you're out in the sun.

"It's like painting a house or room. You put on the first coat as a primer, but it's not a finished job and the coverage isn't even," Weinstock tells WebMD. "Inevitably with the first coat there are some spots missed, and with the second coat it looks like you really painted it."

To get the most sun protection and reduce your risk of skin cancer, experts recommend the following tips when using sunscreen:

  • Apply sunscreen about 20 minutes before heading outdoors and reapply about 20 minutes after being in the sun.

  • Reapply sunscreen every two hours and immediately after swimming or sweating heavily. Sunscreen usually wipes off when you towel off.

  • Waterproof sunscreens are tested to last for up to 80 minutes and should be reapplied at regular intervals if you're in the water for prolonged periods of time. Sunscreens labeled as "water resistant" should be reapplied every 40 minutes.

  • Don't forget to apply sunscreen to the ears, back of the neck, and exposed areas of the scalp. Sunscreen sprays and sticks can be helpful in reaching these often forgotten areas.

  • Both men and women are most likely to get sun-related skin cancers on their nose because it gets the most sun exposure, which makes it a prime target for sunscreen.

  • Foundations, face powders, or other types of makeup that contain sunscreen aren't likely to offer as much SPF protection as indicated on the label because they aren't applied thickly enough. You'll get better protection by using a separate product like a moisturizer containing a high SPF.

  • Ingredients in sunscreen products can lose potency over time. If you notice that the product has changed color, dried up, or changed consistency, it's better to throw it away.

  • If you experience skin irritation from using sunscreen, try one of the newer, chemical-free sunscreens containing zinc oxide or titanium dioxide. These new formulations reflect the sun's damaging rays but don't react with the skin. They can also safely be used around the eyes without causing stinging if the product gets into the eyes after sweating or swimming.

The American Cancer Society recommends using a sunscreen with a sun protection factor of at least 15 or higher, and a palmful of sunscreen should be used to cover the arms, legs, neck, and face of the average adult.

But Weinstock says he recommends using an SPF of at least 30 because most people usually don't put on enough sunscreen to get the maximum sun protection out of it.

"Most people don't want to put it on that thickly and prefer putting it on thinner," says Weinstock. "That's why it's important to use a higher SPF and reapply it often."

When applied properly, a sunscreen with an SPF of 30 blocks out all but one-thirtieth of the sun's burning rays, which allows people to stay out in the sun 30 times longer than they normally would be able to without burning. But when the sunscreen is applied too thinly, the sun protection can be as little as half of the SPF factor listed on the bottle.

The intensity of the sun's damaging UV rays peaks at midday, but you can also find out how strongly the sun is shining in your neighborhood by checking out the daily UV forecast from the National Weather Service, which is available on the Internet and reported in many local newspapers and television news broadcasts.

The forecast measures the amount of UV radiation reaching the ground during an hour around noon on a scale from 0-10+. The higher the number on the scale, the greater exposure to UV radiation and the quicker skin will burn. On a clear, sunny day, the UV index may rise to high (7,8,9) or very high (10+), and skin damage can begin in as little as 15 minutes without sun protection.

Originally published May 22, 2003.
Medically updated June 11, 2004.

SOURCES: Martin Weinstock, MD, PhD, professor of dermatology at Brown University, chair of the American Cancer Society Skin Cancer Advisory Group. Arielle Kauvar, MD, clinical associate professor of dermatology at the New York University School of Medicine and spokeswoman for the American Academy of Dermatology. American Cancer Society. American Academy of Dermatology. News release, United States Pharmacopeia.

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