I have also been looking into substances that have synergy with fluconazole, since I am on fluconazole right now (400mg/day) and it didn't seem to be doing much by itself.
I found this:
Red thyme oil (active ingredient = thymol) has extremely strong action against all species of candida, including mature candida biofilms, and also has a synergistic effect when combined with fluconazole, even against fluconazole-resistant strains:
"Thymol (THY) was found to have in vitro antifungal activity against 24 fluconazole (FLC)-resistant and 12 FLC-susceptible clinical isolates of Candida albicans, standard strain ATCC 10231 and one experimentally induced FLC-resistant C. albicans S-1. In addition, synergism was observed for clinical isolates of C. albicans with combinations of THY–FLC and THY–amphotericin B (AMB) evaluated by the chequerboard microdilution method."
"Positive interaction of thyme (red) essential oil with human polymorphonuclear granulocytes in eradicating intracellular Candida albicans."
Many, many research papers online documenting the strength of red thyme oil against all forms of candida as well as other pathogenic molds and fungus: google search "thyme oil candida," "thymol candida," "thyme oil antifungal," etc. Thymol is relatively low toxicity and used to be the primary remedy for hookworm infections in the US before drugs.
Berberine also has a synergistic effect with fluconazole when combined with fluconazole against fluconazole-resistant strains:
"Fluconazole assists berberine to kill fluconazole-resistant Candida albicans."
I have recently found two products which contain red thyme oil and berberine, and am feeling better than I have in months since I added them together with fluconazole. I am continuing with nystatin every day as well. (I have nothing to do with this company)