Hyaluronic acid is a naturally occurring substance that is already found in your skin. It helps keep skin plump and hydrated. HA fillers are typically soft and gel-like. The results are temporary, lasting 6 to 12 months or longer before the body gradually and naturally absorbs the particles. Most HA fillers are infused with lidocaine to help minimize discomfort during and after treatment. FDA approved HA fillers include: