Restylane is a hyaluronic acid filler, a naturally occurring sugar found in our bodies, that is purified and injected into the skin to fill in facial wrinkles and restore a smoother, firmer and more youthful appearance. Restylane is a family of injectable hyaluronic acid dermal fillers that can help with moderate to severe wrinkles around the mouth, under eye hollows and tear troughs as well as plump up the lips.