Diflucan is very harsh on the liver. That's why the previous poster had to have liver tests periodically while on it. Niastatin is taken orally, but it's not generally absorbed - it just passes through. It only works on the gut, but it's a good start. I buy the pure niastatin powder through a compounding pharmacy so it doesn't have the Sugar in it.
As for the natural anti-fungals, I'm not certain about the liver impact. I suppose raw garlic shouldn't be a problem. I take olive leaf (east park brand is supposed to be the best), and I've never had my liver enzymes go up with it, or heard of anyone who has. It's one of those herbs that don't seem to carry warnings and time limits for how long you can use it.
I also use ozonated water and feel that helps. Of course lots of acidophilus should be fine too.