Yes, I am positive. I started with 5 and used it for almost a year. Hairloss rate seemed to slow down just a bit, but still losing. So, I switched to 10, and my loss was reduced significantly. I thought, why not try 15? And same thing, the loss was noticeably less. Kept at it for many months and then my supply ran out, so I went back to 5 because I still had bottles of that left. Used them for the summer, and started to shed like crazy that whole summer. So, finally got some 10 and 15 again, and the loss became noticeably less. It has been some months now and the loss is still noticeably less than when i used the 5. I regret trying the 5 again because I lost some ground, especially around the hairline.
This is what happened to me. May not be the same for others.
I get my 10s and 15 from minoxidil max. I alternate between the two, but mostly use the 15. Once a night.