I am only on my second bottle. I don't think the effects have diminished. I guess it depends on the type of Candida. Candida Albicans does not become resistant to Nystatin. I didn't get tested for Candida, but since I responded favorably, will assume that it was Candida Albicans (at least, one of the offenders).
A major reason most folks do not take the liquid is because of the high Sucrose content. The powder is more complex to manage, so I opted for a compromise solution that would address my concerns of not having to deal with mixing powder, storing it, etc.
I am only on 300,000Units 3x/day. Sometimes I increase it to 4x/day. I am considering asking my physician to put me on a 2 day/week maintenance dose of Diflucan for a month or 2.