There's still quite a bit of controversy about the safety of its use, but I read all I could and decided to take a chance anyway.
I believe there's a forum somewhere in curezone where I got some helpful info on this - I can't find it now. The basic idea behind it is that candida as well as parasites thrive in an environment where there's not a lot of oxygen. Hydrogen peroxide increases oxygen in the body and in doing so creates an environment where candida cannot thrive
For me so far, it's been the cheapest method (less than $3)that has brought about the biggest change and made me feel very energized. The first two weeks were hell - nausea and fatigue, then that went away by the two and a half week mark.