Dermal fillers, which plump up wrinkles and firm up the skin, are among the hottest and fastest-growing new treatments. Last year, more than 1 million Americans used injectable soft-tissue fillers such as Restylane, Sculptra, and Radiance to compensate for the loss of fat and collagen in the face that comes with age. Restylane, a gel made from hyaluronic acid, has been the subject of several positive clinical trails in the United States and Europe, and the risk of an allergic reaction is very low (1 in 1,600). Most fillers are naturally absorbed by the body and have shown no evidence of building up over time or causing long-term problems. But they are still relatively new. Some people have their own fat injected, which is extremely low risk. Such fat is absorbed fairly quickly, and the effects usually last no more than a couple of months, doctors say.

Restylane is typically injected into the creases from the side of the nose to the corner of the mouth and along the upper lip to fill out fine lines. Restylane and other hyaluronics last three to six months and can cost anywhere from $400 to $1,000 and up, depending on how many vials you need. "Hyaluronics give very nice corrections if the patient isn't too far along," says Robin Schaffran, a Beverly Hills, Calif., dermatologist. "But if you need to use a lot of material it could lump up, and the person would be better off with a face-lift." Sculptra, which is injected deep under the skin to stimulate collagen production, can last up to two years and typically costs at least $3,000 for two treatments.