I started using Certain Dri back when I was a freshman in high school (1997) because I always experienced major sweat stains... I'm happy to say that now, more than 15 years later, I barely IF EVER sweat under my armpits, all thanks to Certain Dri!! I don't use it anymore by the way, I think I used Certain Dri until mid-college (so let's say 6 years total) and realized I was no longer sweating under my arms and didn't need to use it. And as an adult who works with a myriad of people on a daily basis, with high stress levels, it's remarkable to say I no longer sweat under the arms! I do still sweat everywhere else, but I no longer worry about stains on my shirts or that embarrassing feeling like you can't raise your arms in public. If you're thinking of trying this product out, or have mixed feelings about it, don't give up! It may take a long time to get the desired effect but it totally worked for me.