I've been using Envyderm for about three months and am addicted to the stuff! It took a few weeks before there was a noticeable difference in the length and thickness of my lashes but I'm glad I stuck to it because my lashes look awesome. They are much longer and thicker and I don't worry about them braking or falling out when I curl my lashes. I actually have started to trim my bottom lashes becuase they are so long. Now that I have the length I want I only use it every other day instead of everyday. I tried a few other brands before this one but stopped use because I didn't like how they made my eyes feel. No trouble with this one. Be sure that your lashes are completely dry before you put on the serum, it will help it soak in better.