20 Products You Need to Buy the Day You Turn 30

Why: Around 30, my dark under-eye circles started puffing into bags (I blame years of lack of sleep). The best remedy I've found is to deflate them with a serum applied throughout the day (I toss it in my purse and just pull it out on the go). Oils in creams can sometimes build up and cause puffiness, so a gel serum is a better option.

Try: La Mer's The Illuminating Eye Gel ($145) feels soothing and cooling to the touch, and it includes the brand's signature Miracle Broth — a patent antiaging potion.