The right formula will hide undereye circles as well as blemishes and dark spots. Concealers that come in sticks are usually a good choice—creamy enough to blend under the eyes but dry enough to keep a pimple under wraps all day. Look for a shade that matches your skin tone as closely as possible. (If you go a shade lighter, it will work well under your eyes but could accentuate a blemish.)
Great Bets: Clé de Peau Beauté Concealer ($70; department stores); CoverGirl Smoothers Concealer ($6.50; drugstores).