One session lasts six to twelve months, varying by product. The lips move more than anywhere else on the face — talking, eating, smiling — so they absorb quickly. Defining just the border uses less volume than adding fullness, so it fades a little sooner.

Swelling is noticeable for two to three days, because the lips have dense vessels and thin skin, so the reaction after injection is pronounced. Downtime is one to three days and hot food is best avoided on the day; if you are prone to cold sores, say so beforehand so preventive medication can be used.

Hyaluronic acid filler can be reversed with a dissolving injection. A small amount visibly changes the lips, so starting low is safer. Deciding whether to top up after about two weeks, once the swelling has gone and you can see the shape, is more accurate.