Lip injections, in the sense of an external filler to add volume and definition to the lips, is a common cosmetic procedure. Usually, both upper and lower lips are injected because that creates a wonderful dramatic effect. The duration of lip injections varies according to the type of solution used in the lip augmentation. However, it can last from a few months to more than 1 year.
If you are not sure whether your doctor used permanent fillers or temporary ones (hyaluronates) in your lips then it would be great for you to ask him/her. Nevertheless, there is no need for excessive worry.
The hyaluronic acid fillers last from 3-6 months or even more. Since it all depends on the area of injection, volume of filler, thickness of your skin, and other factors that are unknown to me.
The great news is that you can kiss right after lip augmentation, but it should be avoided for no longer than 2 hours. This timeframe should be enough for proper healing after injections.
There are some conditions that need to be met, though. For instance,