Saccharomyces boulardii and Reduced Diarrhea

Research synthesisLow evidenceSmall effect3 studies · 1 beneficial · 2 neutral · 0 harmful

Across 3 randomized controlled trials, 1 reported a beneficial small-sized effect of Saccharomyces boulardii on reduced diarrhea, while 2 found neutral effects. The most-studied dose was 500 mg twice daily, and study populations were clinical (patients with SIBO, IBS-D, or undergoing H. pylori eradication). Median study duration was 15 days.

Effective dose range: 500 mg twice daily
Studied populations: patients with small intestinal bacterial overgrowth (SIBO), patients with diarrhea-predominant IBS (IBS-D), adults undergoing H. pylori eradication

Caveats: Evidence base is small (only 3 studies) — conclusions should be considered preliminary. Many of the included studies did not reach statistical significance — effect may be smaller than the predominant direction suggests.

Generated Jun 9, 2026

Doses used in studies

mg/day: 1,000 (median 1,000, IQR 1,000–1,000) — 2 studies

Time to effect

Median: 2.1 weeks · IQR 13 days–3.6 weeks · Range 10 days–5 weeks — Reported in 3 of 3 studies

Safety in these studies

adverse events (overall)No significant difference
S. boulardii reduced the frequency of adverse events ( P = 0.033) in 14-day regimen, particularly treatment-associated diarrhea ( P = 0.032). However, after the adjustment to control Type I error, results lost their significance.
from: Randomised clinical trial: efficacy and safety of H. pylori eradication treatment with and
diarrheaNo significant difference
S. boulardii reduced the frequency of adverse events ( P = 0.033) in 14-day regimen, particularly treatment-associated diarrhea ( P = 0.032). However, after the adjustment to control Type I error, results lost their significance.
from: Randomised clinical trial: efficacy and safety of H. pylori eradication treatment with and
Overall tolerabilityReported
The safety of S. boulardii CNCM I-745 was excellent.
from: Impact of Saccharomyces boulardii CNCM I-745 on Bacterial Overgrowth and Composition of In

3 of 3 papersPopulation:

[Study on the efficacy of combination therapy with rifaximin and Saccharomyces boulardii CNCM I-745 in patients with small intestinal bacterial overgrowth associated with long-term use of proton pump inhibitors].
- 2025-08-28
- RCT · n = 108
- Terapevticheskii arkhiv 97(8)
- - I V Maev
  - D N Andreev
  - R I Shaburov
  - A V Zaborovsky
  - A K Fomenko
  - P S Sokolov
  - S V Tsaregorodtsev
  - M K Devkota
  - D T Dicheva
  - S V Cheremushkin
  - N V Cheremushkinа
  - A V Vychkin
- PubMed: 40884341
- DOI: 10.26442/00403660.2025.08.203301
7 Insights on
- Reduced Diarrhea
- High evidence
- Large Human Trial
- Clinical
Statistically significant resolution of diarrhea was observed only in Group 2 (p = 0.033)
Effect
Beneficial
Effect size
Small
Significant
Yes
Dose
500 mg twice daily
Randomised clinical trial: efficacy and safety of H. pylori eradication treatment with and without Saccharomyces boulardii supplementation.
- 2023-11-06
- RCT · n = 404
- European journal of cancer prevention : the official journal of the European Cancer Prevention Organisation (ECP) 33(3)
- - Olga Sjomina
  - Inese Poļaka
  - Jekaterina Suhorukova
  - Reinis Vangravs
  - Sergejs Paršutins
  - Viktoria Knaze
  - Jin Young Park
  - Rolando Herrero
  - Raul Murillo
  - Mārcis Leja
- PubMed: 37942999
- DOI: 10.1097/cej.0000000000000858
2 Insights on
- Reduced Diarrhea
- High evidence
- Large Human Trial
- Adults
S. boulardii reduced the frequency of adverse events (P = 0.033) in 14-day regimen, particularly treatment-associated diarrhea (P = 0.032). However, after the adjustment to control Type I error, results lost their significance.
Effect
Neutral
Effect size
Small
Significant
No
Dose
500 mg BID
Impact of Saccharomyces boulardii CNCM I-745 on Bacterial Overgrowth and Composition of Intestinal Microbiota in Diarrhea-Predominant Irritable Bowel Syndrome Patients: Results of a Randomized Pilot Study.
- 2023
- RCT · n = 54
- Digestive diseases (Basel, Switzerland) 41(5)
- - Luis Maria Bustos Fernández
  - Fernando Man
  - Juan Sebastián Lasa
- PubMed: 36630947
- DOI: 10.1159/000528954
3 Insights on
- Reduced Diarrhea
- High evidence
- Clinical
The proportion of patients with diarrhea was lower in the Sb + DA group than in the DA group (25.9% compared to 47.6%).
Effect
Neutral
Effect size
Small
Significant
No
Dose
not specified

Saccharomyces boulardii and Reduced Diarrhea

[Study on the efficacy of combination therapy with rifaximin and Saccharomyces boulardii CNCM I-745 in patients with small intestinal bacterial overgrowth associated with long-term use of proton pump inhibitors].

Randomised clinical trial: efficacy and safety of H. pylori eradication treatment with and without Saccharomyces boulardii supplementation.

Impact of Saccharomyces boulardii CNCM I-745 on Bacterial Overgrowth and Composition of Intestinal Microbiota in Diarrhea-Predominant Irritable Bowel Syndrome Patients: Results of a Randomized Pilot Study.