The first thing to clear up with this question is that we are really addressing not how long the filler "lasts," but instead how long it provides the desired correction. In reality, the filler starts getting degraded the second it is injected, and many factors will affect the rate of that degradation. This is not an all or nothing phenomenon, meaning that the filler doesn't stay put and all of a sudden just one day disappear, it is a slow and gradual process.The six months that you often see quoted is based on the FDA trials for these products where they were looking at endpoints of correction. Once the product dropped below that endpoint that was arbitrarily set as determining whether the product worked or not, it's duration was set. That does not mean that the product was all gone, it just means that as far as that FDA arbitrarily set standard, it was not meeting it anymore. What that all means for you is: you may not have the same rigid standard set that the FDA does for correction, so you may think that it "lasts" much longer or shorter in yourself. It is true that the product does go away, but it happens slowly over time, so even if you start to notice a bit of a loss with time, you may not need as much product in the future to get that desired correction again, because there's still likely some product left behind.I have seen with my own eyes filler such as Juvederm or Restylane that is still present in the tissue more than a year after its original injection histologically while removing a skin cancer in the area. There are definitely some factors that affect the duration of filler: 1. Placement of the filler is important, if it is placed in and active area it will be moved and agitated more exposing it to the enzyme in our skin that dissolves it, and thus it will go away faster in these areas of high movement. Your injector's skill and knowing the proper planes and location to put it in is also very important when considering this.2. The product itself does matter. More highly cross-linked products will last longer, but as you can see by reading through other people's answers, there is great debate as to which products last longer, and honestly there is not a good answer for that. Doctors' opinions are all over the board, which tells you that nobody really knows - even the ones that think they do, as these are all reputable opinions. For some of the newer hyaluronic acid fillers such as Voluma or Perlane, even the FDA agrees they last longer, up to two years. When you get into other classes of fillers, such as Sculptra, you can look at durations that are even longer than that.3. Often unspoken, but equally important; if you had prior filler, the current filler will likely last longer if placed in the same area. This goes back to what I mentioned before about having some residual product in the skin, even if it is not providing noticeable correction.To ensure you are receiving the highest level of care, seek out a dermatologic surgeon, oculoplastic surgeon, facial plastic surgeon or plastic surgeon who is board certified and fellowship trained in one of these "core four" cosmetic specialties.
