What Is Hyaluronic Acid? Hyaluronic acid, often abbreviated as HA, is a substance naturally found in the body. In aesthetic medicine, specially formulated hyaluronic acid gels are used in certain injectable dermal fillers to create temporary fullness or smoothness in specific areas of the face. The FDA has approved certain dermal fillers for lip augmentation in adults who meet the applicable age and treatment criteria. HA filler used for the lips is not simply natural hyaluro