Lip fillers enhance the size and shape of the lips. They are usually made with hyaluronic acid which is a natural substance found in the body. Filler is injected into the lips to enhance their shape and volume. The doctor marks the area to be treated and use fine needles to inject the filler. The doctor will massage the treated region to smooth out any bumps and create a natural appearance. Collagen filler injections are rarely used as they require skin testing since the collagen is typically derived from cow protein. Fat grafting requires liposuction in order to remove fat from the body of the patient. The fat is then re-injected into the lips.