Kay Durairaj, M.D., F.A.C.S., a Pasadena, California-based facial plastic surgeon tells Shape, "The typical scenario is that the filler will migrate just beyond the border of the lip, which is called the vermilion border, and it goes into the skin or cutaneous portion of the lip."

Lip filler migration can happen for a variety of reasons. One of the reasons lip filler migrates is when the wrong type of filler is used by an inexperienced injector. Hyaluronic acid fillers are the most popular and recommended fillers when trying to avoid migration and achieve a natural, plump look. When lip injections are placed too closely together or there are too many injections at the border of the lips, it's more likely you will experience migration. Fortunately, there are some preventative and cautionary steps and measures you can take to stop your filler from migrating.