One of the shortcomings (albeit negligible) of dermal fillers is that the results are non-permanent. While a lot of progress has been made on increasing the duration of effects (collagen lasts for about 3 months while hyaluronic acid based fillers could last for up to a year), average dermal filler treatments tend to last for six to eight months. This period depends on the substance injected and also to some extent, the part of the body that was injected. You should talk with your physician about how long the injection is expected to last and when you need to come back for maintenance injections.