Hi, Angie, welcome to the board! Be sure to check out uvicf.org , which has a lot of information about GSH under its "Research" heading. Anyhow, all living things that use oxygen make and use GSH. Including humans . . . and including bacteria and fungi. If your fungus problems are to the point where you are using an anti-fungal, hold off on the GSH so the killing will be more effective. Remember, however, that normal persons have 10 times more GSH in their extracellular space than CF folks, and they kick fungus and bacteria much better than CF folks. So it's not a black and white situation. But if it were me, I'd stop GSH while taking anti-fungals.