I'll tell you something, since I've been using it for the past 4 weeks, I've noticed that it has decreased the amount of the hair that I was losing. How do I know, well when showering run your fingers through your hair when you are shampooing, if you are losing hair, you'll see bunch of hair on your hands, but once you start using propecia, the amount of hair will be significantly decreased or none existant. Or even look at your pillow...do you see hair on it? That will be gone too!