What they are: Doctor- or aesthetician-administered treatments that use either a chemical (hydroxy acids or trichloroacetic acid) or mechanical process (microdermabrasion) to lift away the upper layers of the skin.

How they work: For a chemical peel, an acid solution is painted on the face like a mask. The higher the concentration (or the longer it is left on), the more layers of skin that will be peeled away. Microdermabrasion uses aluminum oxide crystals to buff away dead skin cells. "Many women need more exfoliation around the nose, mid-forehead, and chin, and with mechanical exfoliation, it's easier to focus on those areas," says Heidi Waldorf, MD, associate clinical professor of dermatology at the Mount Sinai School of Medicine. Some doctors are praising a newer system called Vibraderm, which uses vibrating metal paddles to exfoliate the skin. Eliot F. Battle Jr., MD, assistant clinical professor of dermatology at Howard University, prefers it for his African-American patients because the paddles are gentler than crystals—important for dark skin, which is vulnerable to spots when it becomes irritated or traumatized. More and more microdermabrasion techniques are also marrying exfoliation with topical treatments. The Vibraderm treatment can be followed up with a solution of antioxidants, glycolic acid, collagen, or bleaching agents. The SilkPeel or DermaSweep machines remove dead cells while delivering either hydroquinone to lighten dark spots, salicylic acid to heal acne, or hyaluronic acid to hydrate dry patches.

Results: One light chemical peel or microdermabrasion treatment will leave the skin temporarily brighter; a series of at least four is necessary to get results that can last several months, like a smoothing of rough patches and more even pigmentation.

Medium or deep chemical peels should be done only in a doctor's office. Because these peels reach all the way to the dermis, collagen production is stimulated with one treatment. Fine lines are effaced, and skin may even be slightly tighter.