Star power: More than 90 percent of the wrinkles, dark spots and crepiness attributed to aging is caused by sun exposure. The UV filters in sunscreen absorb or scatter UV light before it can damage your skin; in effect, they stop aging.
What to look for on the label: Broad-spectrum (meaning the product blocks both UVA and UVB rays). For days spent outdoors, also look for water-resistant (either for 40 or 80 minutes). You may prefer the silky texture of a chemical sunscreen (like avobenzone, oxybenzone and brand names Helioplex and Mexoryl), but a physical sunscreen (zinc oxide and titanium dioxide) is less potentially irritating and now a good choice for every skin tone because micronized formulas don't look chalky. Physical sunscreens also absorb excess oil—good if you have shiny skin.
For best results: Apply sunscreen with at least an SPF 30 before you leave the house in the morning (if it's a chemical sunscreen, give it 15 minutes to start working); reapply every two to three hours if you are outside all day. Use about a teaspoonful of sunscreen on your face. (This is a lot of sunscreen; use as much as you can tolerate.)
You should know: Did you believe the myth that we get most of our sun exposure in childhood? In fact, less than 25 percent of lifetime sun exposure occurs before the age of 18, and less than 50 percent before you're 40.
Lancôme Bienfait UV SPF 50+ ($38; lancome.com)
Clinique Sun Broad Spectrum SPF 50 Sunscreen Body Cream ($23; clinique.com)
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