As long as you get your injections done by a trained professional, collagen lip treatments are very safe. Make sure the doctor you choose only uses injection procedures that are approved by the U.S. Food and Drug Administration (FDA). It may sound surprising, but many doctors offer injectable treatments that haven't yet been approved.
Your doctor should administer a local anesthetic to your lips before the procedure. You may experience a few side effects afterwards, but these should go away after a few days. Possible side effects include redness, swelling or tenderness at the injection sight. These symptoms are expected for one to three days. If they don't go away, however, notify your doctor, as they could be a sign of an infection [source: Essig].
How you react to a collagen injection could depend on what kind of collagen actually gets inserted into your lips. Bovine-derived collagen injections may cause an allergic reaction in some people. If you are going to use a bovine-derived injection, your doctor should do a skin test about a month before treatment to make sure you're not allergic to it. Human-derived collagen, on the other hand, is much less likely to cause an allergic reaction. You can even inject collagen into your lips that comes from a completely different spot on your own body. That way, the chances are higher that you won't have an adverse reaction to it [source: Essig].
Where your collagen injection comes from affects more than just your reaction to it. Collagen treatments from different sources can vary in how long they last. To learn more about the effectiveness of various collagen lip injections, see the next page.