What is Saccharomyces boulardii used for?

What is Saccharomyces boulardii Good For?

Saccharomyces boulardii is primarily indicated for preventing Clostridioides difficile infection in adults and children receiving antibiotics, where it reduces the risk by approximately 59%. 1

Primary Evidence-Based Indication

Prevention of C. difficile Infection During Antibiotic Therapy

• The American Gastroenterological Association conditionally recommends S. boulardii for preventing C. difficile infection in patients on antibiotics (RR 0.41; 95% CI 0.22-0.79), demonstrating superior efficacy compared to placebo. 1

• S. boulardii reduces both the cessation of diarrhea (RR 1.33; 95% CI 1.02-1.74) and recurrence of C. difficile-associated diarrhea (RR 0.59; 95% CI 0.35-0.98). 1

• The unique advantage of S. boulardii is that antibiotics do not kill yeast, allowing it to survive concurrent antibiotic exposure and colonize disrupted gut niches that opportunistic pathogens would otherwise exploit. 1, 2

• S. boulardii is the only single-strain probiotic demonstrating significant reduction in C. difficile-associated diarrhea incidence among all probiotics studied. 2

Dosing and Administration

• Effective dosing is 1 gram (or 3×10¹⁰ CFU) daily, started at the beginning of antibiotic therapy and continued throughout the entire antibiotic course. 2, 3

Secondary Indications with Limited Evidence

Pouchitis Maintenance (Not S. boulardii Specifically)

• The AGA suggests using an 8-strain probiotic combination (not S. boulardii) for maintenance of remission in chronic pouchitis following ileal pouch-anal anastomosis for ulcerative colitis. 1

• S. boulardii itself has not been adequately studied for pouchitis management. 1

Conditions Where S. boulardii is NOT Recommended

Irritable Bowel Syndrome

• The AGA makes no recommendation for S. boulardii in IBS due to lack of efficacy. Three studies involving 232 adults with IBS found no difference between S. boulardii and placebo for abdominal pain scores (standardized MD 0.26; 95% CI -0.09 to 0.61). 1

• The AGA recommends probiotics for IBS only in the context of clinical trials due to very low quality evidence and significant heterogeneity. 1

Abdominal Bloating

• Treatment with probiotics including S. boulardii is not recommended for bloating or distention. 4

• S. boulardii showed no benefit for abdominal symptoms in IBS patients, and probiotics may actually worsen bloating in some individuals. 4

Acute Infectious Gastroenteritis in Children

• The AGA suggests against the use of probiotics including S. boulardii in children with acute infectious gastroenteritis in the United States and Canada (conditional recommendation, moderate quality evidence). 1

Critical Safety Considerations

Absolute Contraindications

• S. boulardii is absolutely contraindicated in immunocompromised patients due to risk of fungemia or systemic yeast infection. 2, 3

• This includes patients with central venous catheters, severe immunosuppression, or critical illness. 2

Risk-Benefit Assessment

• Patients with severe underlying illnesses should avoid S. boulardii due to potential harms outweighing benefits. 1

• Outpatients with low baseline risk of C. difficile infection may reasonably decline probiotics given the associated cost and minimal absolute risk reduction. 1

Clinical Algorithm for Use

Step 1: Patient prescribed antibiotics → Assess for immunocompromised status or severe illness

Step 2: If immunocompetent → Consider baseline C. difficile risk (hospitalized patients, recent healthcare exposure, advanced age, multiple antibiotics)

Step 3: If moderate-to-high C. difficile risk → Recommend S. boulardii 1 gram daily starting with first antibiotic dose and continuing throughout entire antibiotic course 2

Step 4: If low C. difficile risk (healthy outpatient) → Discuss optional use based on patient values regarding cost versus small absolute benefit 1

Quality of Evidence and Limitations

• The overall certainty of evidence for S. boulardii in C. difficile prevention is low, downgraded due to unclear or high risk of bias in most trials, heterogeneous populations, and potential publication bias. 1

• Despite low quality evidence, S. boulardii remains the best-studied single-strain probiotic for this indication with consistent directional benefit. 1, 2

• The mechanisms by which S. boulardii exerts protective effects include improvement of gut barrier function, competitive exclusion of pathogens, production of antimicrobial factors, and immune modulation. 5, 6