MYTH #1: SPF STANDS FOR "SUN-PROOFING FACTOR." Nope, SPF stands for "sun protection factor"; no sunscreen can provide a complete barrier. SPF is based on the amount of time needed to cause redness in unprotected skin, says Amy Wechsler, M.D., a dermatologist in New York City. If you'd burn in ten minutes on a given day if you weren't wearing sunscreen, for instance, a sunscreen with an SPF of 2 would let you stay outside for 20 minutes before you started to toast. For two and a half hours of skin-safe fun, you'd need to reach for a tube of something SPF 15 or higher, and so on.
MYTH #2: MY KIDS NEED TO USE A SUNSCREEN THAT'S SPECIALLY DESIGNED FOR CHILDREN. Only babies under 6 months old need a special formula--one with titanium dioxide or zinc oxide in it. Those ingredients form a physical barrier to the sun's rays and aren't absorbed into the epidermis. But after that, your kids can use the same sunscreen you do (though it's always good to avoid fragranced ones if they or any family member has sensitive skin).
MYTH #3: IF THE BOTTLE SAYS SPF 30, THAT'S EXACTLY THE AMOUNT OF PROTECTION I'M GETTING. Only if you use enough of what's inside. Experts advise applying at least a shotglass's worth of sunscreen over your body. Using a spray formula? Dr. Wechsler's rule of thumb: "You've applied enough when the skin doesn't readily absorb any more." Then reapply every two hours, or wear a UVSunSense wristband ($7 for seven; amazon.com), which gauges the sun's intensity and changes color when it's time to lube up again.
MYTH #4: IT'S FINE TO USE LAST YEAR'S SUNSCREEN. Unfortunately, no. "Sunscreen has an expiration date, and you need to pay attention to it because the active ingredients will start to lose their effectiveness after that time," says Dr. Wechsler. If you bought a bottle last year and never opened it, and it hasn't expired, go ahead and use it this summer, she says. "But if it's half-finished and was in and out of your house, out in the heat, I'd toss it," she advises.
MYTH #5: IT'S SMART TO RUB ON SOME SUNSCREEN AS SOON AS I HIT THE BEACH. It's usually smarter to put it on before you hit the beach. Many products' active ingredients are chemicals that need some time to sink into your skin to become effective, so try your best to apply sunscreen about 20 minutes before you go out. Also, if you wait until you're outdoors and feeling the heat, sweat might make it harder to rub in the lotion.
The Great Cover-Up
Sunscreens are fine and good, but the best way to protect skin is to keep it under wraps. Not all clothes are created equal, though: A lightweight, lightcolor tee offers only an SPF of about 4, says Karen Rothman, M.D., a pediatric dermatologist at UMass Memorial Children's Medical Center, in Worcester, MA. You can buy clothes with SPF from companies such as Coolibar, Alex & Me, and Solartex. Or you can wash your family's duds with SunGuard; it'll boost the fabrics' SPF to 30. $1.99 per pack; sunguardsunprotection.com
It happens: Sometimes, despite your awesome efforts, your kid gets too much sun. If the sole symptom is redness, keep the area moisturized. Offer ibuprofen (to kids 6 months and older only) or acetaminophen for pain, but steer clear of numbing creams containing benzocaine because some people are sensitive to it, says Maria Tsoukas, M.D., assistant professor at the University of Chicago Pritzker School of Medicine. If your child's skin blisters, don't pop them; call your pediatrician, who may recommend that you take your child to the ER.