Restylane® and Juvederm® are two different brands of FDA-approved dermal fillers made of hyaluronic acid, a naturally occurring substance in the body. These products are obtained from non-animal sources and are safe and natural cosmetic fillers that help to reduce the appearance of deep lines, creases, and hollows in the face. Unlike traditionally used collagen fillers, Restylane® and Juvederm® products do not require any pre-treatment skin testing. The areas most commonly treated are the nasolabial folds (smile lines), melolabial folds (marionette lines), and tear trough deformity (hollows beneath the eyes). In addition, these products have also been very successfully used to augment the lips or elevate the eyebrows. Restylane® and Juvederm® treatment effects do fade with time, although the timing is variable from patient to patient. Most patients request re-treatment about every three to four months for the lips and about every six to nine months for other treatment areas.