Saccharomyces boulardii
Research reviewed: Up until 03/2026
Saccharomyces boulardii (Saccharomyces boulardii CNCM I-745) is a dietary supplement with 10 published peer-reviewed studies involving 452 participants, researched for Antibiotic-Associated Diarrhea, C. difficile Infection, IBS & IBD and 2 more areas.
Evidence at a Glance
Strength is scored by study design, sample size, study type, and outcomes
Antibiotic-Associated Diarrhea
ModerateC. difficile Infection
ModerateIBS & IBD
StrongAcute Diarrhea
WeakGut Health & Infections
ModerateResearch Visualised
Visual breakdown of the clinical data.
Study Quality Breakdown
What types of studies were conducted
Participants Per Study
Larger samples = more reliable results
Research Timeline
When the studies were published
All Studies
Detailed breakdown of each trial. Click to expand.
Antibiotic-Associated Diarrhea
To evaluate S. boulardii for prevention of antibiotic-associated diarrhea.
Study Type
Meta-analysis
Purpose
To evaluate S. boulardii for prevention of antibiotic-associated diarrhea.
Dose
250-1000 mg/day across studies
Participants
Meta-analysis of 10 RCTs, 3432 patients
Duration
Various
Results
S. boulardii significantly reduced risk of AAD (RR 0.47, 95% CI 0.35-0.63). NNT = 10. Effects were consistent across all antibiotic classes.
How They Measured It
Pooled risk ratios across included RCTs
To assess S. boulardii for prevention of AAD in hospitalized patients.
Study Type
Randomised, double-blind, placebo-controlled
Purpose
To assess S. boulardii for prevention of AAD in hospitalized patients.
Dose
500 mg twice daily
Participants
180 hospitalized patients
Duration
Duration of antibiotic course + 3 days
Results
S. boulardii significantly reduced AAD incidence (7.2% vs 14.6% placebo). Duration of diarrhea was also shorter in treated group.
How They Measured It
Incidence and duration of diarrhea
C. difficile Infection
To evaluate S. boulardii for prevention of recurrent C. difficile infection.
Study Type
Randomised, double-blind, placebo-controlled
Purpose
To evaluate S. boulardii for prevention of recurrent C. difficile infection.
Dose
1 g/day
Participants
124 patients with C. difficile infection
Duration
4 weeks
Results
S. boulardii combined with standard antibiotics significantly reduced C. difficile recurrence (34.6% vs 64.7% in high-dose vancomycin subgroup).
How They Measured It
Recurrence rate of C. difficile diarrhea
To evaluate S. boulardii for prevention and treatment of C. difficile-associated disease.
Study Type
Systematic review and meta-analysis
Purpose
To evaluate S. boulardii for prevention and treatment of C. difficile-associated disease.
Dose
Various
Participants
Meta-analysis of 5 RCTs, 1076 patients
Duration
Various
Results
S. boulardii significantly reduced risk of C. difficile recurrence (RR 0.59, 95% CI 0.41-0.85). Evidence strongest for recurrent C. difficile.
How They Measured It
Pooled risk ratios for recurrence
IBS & IBD
To evaluate S. boulardii for IBS-D symptoms.
Study Type
Randomised, double-blind, placebo-controlled
Purpose
To evaluate S. boulardii for IBS-D symptoms.
Dose
750 mg/day
Participants
67 IBS-D patients
Duration
4 weeks
Results
S. boulardii significantly improved quality of life scores and reduced stool frequency compared to placebo. Modest improvement in abdominal pain.
How They Measured It
IBS-QoL, stool frequency and consistency, abdominal pain
To evaluate S. boulardii as adjunct therapy in Crohn's disease.
Study Type
Randomised, double-blind, placebo-controlled
Purpose
To evaluate S. boulardii as adjunct therapy in Crohn's disease.
Dose
1 g/day
Participants
32 patients with Crohn's disease in remission
Duration
6 months
Results
S. boulardii group had significantly lower relapse rate (6.25% vs 37.5% placebo) and maintained lower CDAI scores.
How They Measured It
CDAI, relapse rate
To assess S. boulardii in ulcerative colitis maintenance therapy.
Study Type
Randomised controlled trial
Purpose
To assess S. boulardii in ulcerative colitis maintenance therapy.
Dose
750 mg/day
Participants
25 patients with UC in remission
Duration
12 months
Results
S. boulardii as adjunct to mesalamine showed clinical improvement but did not reach statistical significance for relapse prevention compared to mesalamine alone.
How They Measured It
Clinical Activity Index, endoscopic scores, relapse rate
Acute Diarrhea
To evaluate S. boulardii for treatment of acute diarrhea in children.
Study Type
Meta-analysis
Purpose
To evaluate S. boulardii for treatment of acute diarrhea in children.
Dose
250-500 mg/day across studies
Participants
Meta-analysis of 9 RCTs, 1117 children
Duration
3-7 days
Results
S. boulardii significantly reduced duration of acute diarrhea by ~24 hours (WMD −23.1 hours, 95% CI −31.7 to −14.5). Effective in both viral and bacterial diarrhea.
How They Measured It
Duration of diarrhea, stool frequency
Gut Health & Infections
To evaluate the efficacy and safety of Saccharomyces boulardii combined with standard quadruple therapy for H. pylori eradication in adults.
Study Type
Meta-Analysis
Purpose
To evaluate the efficacy and safety of Saccharomyces boulardii combined with standard quadruple therapy for H. pylori eradication in adults.
Dose
S. boulardii CNCM I-745 500-1000 mg/day alongside quadruple therapy
Participants
Meta-analysis of adults with H. pylori infection
Duration
Various
Results
S. boulardii addition to quadruple therapy significantly improved eradication rates and reduced adverse effects, particularly diarrhea.
How They Measured It
H. pylori eradication rates, adverse effects (diarrhea, nausea, taste disturbance)
To evaluate combination therapy of rifaximin and Saccharomyces boulardii CNCM I-745 for small intestinal bacterial overgrowth.
Study Type
Randomized Controlled Trial
Purpose
To evaluate combination therapy of rifaximin and Saccharomyces boulardii CNCM I-745 for small intestinal bacterial overgrowth.
Dose
S. boulardii CNCM I-745 500 mg twice daily plus rifaximin
Participants
Patients with SIBO associated with PPI use
Duration
4 weeks
Results
Combined rifaximin and S. boulardii therapy showed superior SIBO eradication rates and symptom improvement compared to rifaximin alone.
How They Measured It
SIBO breath test results, symptom scores, gut microbiome markers
Frequently Asked Questions
Common questions about Saccharomyces boulardii research
There are currently 10 peer-reviewed studies on Saccharomyces boulardii (Saccharomyces boulardii CNCM I-745), involving 452 total participants. Research covers Diarrhea prevention, C. difficile infection, IBD support and 1 more areas. The overall evidence strength is rated as Strong.
The evidence is currently rated as "Strong Evidence". This rating is based on study design quality (randomisation, blinding, placebo controls), sample sizes, study types (6 human studies), and reported outcomes.
Saccharomyces boulardii has been researched for: Diarrhea prevention, C. difficile infection, IBD support, Gut health. Each area has its own body of evidence which you can explore in the study breakdowns above.
Yes, 6 out of 10 studies are human trials. Human trials carry more weight in our evidence scoring system.
