To fill depressions or lines in the skin both collagen and fat injections are used. A normal component of all skin is collagen, but the material used for injection is prepared from calf skin. All patients must be tested for an allergic to this foreign protein. Both the deeper and shallow layers of the skin are injected with collagen in order to fill up a line or depression .Depending in the area injected; the range of discomfort can range from none to mild, during the injections. The procedure is done in the doctor's office. A patient can return to work immediately and can also wear make up after the procedure. Collagen injections only provide temporary improvement since collagen is gradually broken down by the body. Typically you are provided significant improvement for three to six months. The patient's own fatty tissue is another substance that can be injected beneath lines and depressions. There is no risk to allergy but much of the fat injected does not survive the transplant process. Usually more than one injection is required. After a series of injections the correction can be quite satisfactory since some fat does survive indefinitely. Results can be long lasting but fat injections usually result in more swelling, discomfort and bruising. Please contact a cosmetic or plastic surgeon for more information.