If you're buying lotion for a day of swimming, choose a sunblock with more staying power in the water than ordinary sunscreen. The American Academy of Pediatrics (AAP) recommends applying any sunscreen about 30 minutes before your child needs it and then reapplying at least every two hours. Even specially formulated sunscreens can lose their effectiveness in water or through sweat from play. "No sunscreen is absolute. They do wash off," says Dr. Karen Sherwood, MD, a dermatologist at Children's Hospital Los Angeles. "If you're in water, for example, an SPF 30 washes off to about a 15, and a 15 washes off to an 8." You're not safe just because you stay in the water, either; UV rays also reach below water's surface.
Don't be skimpy when applying sunblock. "You need to put it on thicker than you think to truly work; most people don't put on enough," says Dr. Sherwood. "One little squirt on an arm is not enough. Put a nice thick glob on and rub." Be especially generous on sensitive areas such as the ears, nose, lips, and shoulders. You may want to try a zinc oxide or titanium oxide product on these areas. These visible, opaque sunblocks keep all harmful rays from penetrating the skin. Children can also use an SPF 15 balm for lips.
It's important to use sunscreen on cloudy days, too. Up to 80 percent of the sun's rays can penetrate clouds, meaning skin damage can still occur on overcast outings.
Be sure to check last summer's sunscreen for an expiration date. Sunscreens' protective properties can change with time, so if your lotion has changed consistency, is dried up, or smells funny, throw it out and buy a new bottle. When trying a new product, do a patch test (the underarm is a good place) to be sure your child doesn't have an allergic reaction. If she develops a rash or irritation, try a hypoallergenic sunblock.
The best way to avoid sun damage is to stay in the shade. This is especially important between the hours of 10 AM and 3 PM when the sun's rays are most dangerous. If your child is taking a medication that increases sun sensitivity, keep him or her in a shaded area. The ACS recommends teaching your children the shadow rule: If your child's shadow is shorter than he is, the sun is high in the sky, and the UV rays are intense.