I've used the serum every evening for 2.5 months. In the first month, I noticed no difference at all in my lashes, and I felt a bit of a sting when I applied it. After about 1 month, I noticed a little result when I started using more product and really drenched the lashes and lash line with product. The lashes are a bit longer and a bit fuller, but nothing wow. I used x-lash before, and it gave results quickly and more noticeably, but I got very blue under my eyes when I used it. I will use wowbrow, but if I don't get longer lashes than now, I will probably buy another serum next time.