Supplement analysis backed by scientific evidence · PT

← All supplements
Moderate evidenceGut health

Saccharomyces Boulardii

A probiotic yeast with genuinely good evidence for preventing antibiotic-associated diarrhoea and reducing the side effects of H. pylori eradication. Because it is a yeast, it survives antibiotics — but it can cause fungaemia in critically ill and catheterised patients, which is a real, documented risk.

What the science says

  • Prevents antibiotic-associated diarrhoea Strong evidence

    A systematic review with meta-analysis of 21 RCTs (n≈4,780) found S. boulardii reduced the risk of antibiotic-associated diarrhoea from about 18.7% to 8.5% (RR ~0.47), in both children and adults. This is one of the better-supported probiotic indications, and the effect is strain-specific to S. boulardii CNCM I-745.

  • Improves tolerance of H. pylori eradication therapy Moderate evidence

    A meta-analysis of 18 RCTs found adding S. boulardii to standard eradication regimens modestly raised eradication rates (RR ~1.11) and clearly reduced overall therapy-related adverse effects, particularly diarrhoea (RR ~0.51). The symptom benefit is more convincing than the eradication benefit.

  • Treats acute infectious diarrhoea in children Moderate evidence

    Pooled trials show S. boulardii shortens acute gastroenteritis by roughly 24 hours and reduces stool frequency, though trial quality is variable and most data come from settings without routine rotavirus vaccination. Benefit is smaller in vaccinated, well-nourished populations.

  • Prevents C. difficile infection recurrence Limited evidence

    Despite widespread marketing, evidence for preventing primary or recurrent C. difficile infection is inconsistent — some trials show benefit in recurrent disease when combined with high-dose vancomycin, but pooled results are not robust enough to recommend it for this purpose.

Dosage & safety

Studied dose250-500 mg twice daily (roughly 5-10 billion CFU/day; 1 g of the lyophilised preparation ≈ 2×10^10 CFU). For antibiotic-associated diarrhoea, start with the antibiotic and continue for at least a week after finishing. Unlike bacterial probiotics it is not killed by antibiotics, so it can be taken at the same time.
SafetyThe important risk is fungaemia: dozens of cases of S. boulardii bloodstream infection are documented, almost all in critically ill, immunocompromised or central-venous-catheter patients, including some acquired from opening capsules near a catheter. Contraindicated in ICU patients, the immunosuppressed, those with central lines, and anyone with a yeast allergy. It is a live yeast, so avoid combining with systemic antifungals (which inactivate it). Commonly causes mild gas, bloating, thirst and constipation. Not a substitute for antibiotics in C. difficile infection. Regulatory status varies — it is a licensed medicine (Florastor, Ultra-Levure, Enterol) in parts of Europe and Asia but sold as a dietary supplement in the US.

Scientific references

Where to buy

NOW Foods, Saccharomyces Boulardii, Probiotic , 5 Billion CFU, 60 Veg Capsules

View on iHerb

Referral link — this site may earn a commission on purchases.

Related in Gut health