NutriStack
Fluconazole and Saccharomyces Boulardii, a conflict.
Saccharomyces boulardii is itself a yeast (a non-pathogenic strain of S. cerevisiae). Fluconazole has variable activity against Saccharomyces species and may suppress S. boulardii during therapy, defeating its probiotic purpose. Rare cases of S. boulardii fungemia have occurred in immunocompromised or central-line patients, where antifungal activity is desirable.
One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
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From the interaction database
What the row says.
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At a glance
- Substances
- Fluconazole and Saccharomyces Boulardii
- Pair type
- Conflict
- Evidence (highest tier)
- Emerging
- Source citations
- 2 sources
- Stack Score effect
- −10 to your Stack Score (per scored conflict row).
- Scope
- Supplement × Prescription
- Last verified
- May 30, 2026
Conflict · Emerging evidence
Conflict
What is happening. Saccharomyces boulardii is itself a yeast (a non-pathogenic strain of S. cerevisiae). Fluconazole has variable activity against Saccharomyces species and may suppress S. boulardii during therapy, defeating its probiotic purpose. Rare cases of S. boulardii fungemia have occurred in immunocompromised or central-line patients, where antifungal activity is desirable.
Mechanism. Fluconazole inhibits fungal ergosterol synthesis via CYP51, which affects S. boulardii to varying degrees and undermines viability of the probiotic.
Recommendation. Hold Saccharomyces boulardii during your fluconazole course. Resume a few days after finishing fluconazole if you still want probiotic support. Lactobacillus-based probiotics are unaffected by fluconazole.
Sources (2)
- Suchodolski J, et al. Capric acid secreted by Saccharomyces boulardii influences the susceptibility of Candida albicans to fluconazole and amphotericin B. Sci Rep. 2021;11(1):6519. PMID 33753842
- Tomičić R, Tomičić Z, Raspor P. Influence of culture conditions on co-aggregation of probiotic yeast Saccharomyces boulardii with Candida spp. Folia Microbiol (Praha). 2022;67(3):507-515. PMID 35169980
Stack Score
How this pair moves the number.
Effect on the composite score
If both Fluconazole and Saccharomyces Boulardii are in the same stack, this pair applies −10 to your Stack Score (per scored conflict row).
The full algorithm, the clamping rules, and four worked stacks are documented at /methodology/stack-score.
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