SkinCeuticals Physical Fusion UV Defense SPF 50

Photo: Courtesy of SkinCeuticals

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Need It: A Sunscreen
This is the only product that will prevent your skin from aging in the first place. Use it early (at least 20 minutes before you leave the house) and often (reapply every two hours if you're spending the day outside). The best sunscreen is the one that you will use consistently, so find a texture that works for you. Many moisturizers now include sunscreen; tinted sunscreens double as makeup and won't look chalky. We like SkinCeuticals Physical Fusion UV Defense SPF 50 ($60 for 125 milliliters; SkinCeuticals.com). Don't forget to apply sunscreen on all exposed skin—which, on most days, includes your neck.