Reapplying Sunscreen

How often do you need to re-apply sunscreen? After your initial A.M. application, do touch-ups every two hours, especially if you're spending a lot of time in direct sunlight. "Sunscreen formulas get diluted by sweat and broken down by the sun," says Dr. Kauvar. Hanging out inside? You're still not off the hook: Fifty percent of UVA rays penetrate windows, so be sure to do spot touch-ups using a stick with SPF 30, or brush a micronized zinc-oxide powder over makeup.