Saccharomyces boulardii is a non-pathogenic, thermophilic, probiotic yeast strain, distinct from brewer's or baker's yeast (S. cerevisiae). It is a live biotherapeutic agent with proven efficacy in preventing and treating various forms of diarrhea, particularly antibiotic-associated diarrhea (AAD) and acute infectious diarrhea. It exerts its effects through multiple mechanisms including pathogen inhibition, toxin neutralization, immune modulation, and trophic effects on the intestinal mucosa. It is not a permanent colonizer of the human gut and is eliminated within 3-5 days of cessation.
Adult: 250-500 mg (typically 250mg capsule) once or twice daily. For AAD prevention: 250mg twice daily during antibiotic course and for 5-7 days after. For acute diarrhea: 500mg twice daily for 5-7 days.
Note: Administer orally. Capsules should be swallowed whole with a cool or lukewarm liquid (NOT hot, as heat kills the yeast). Can be opened and mixed with cool water, yogurt, or formula for children or those unable to swallow capsules. Take at least 2-3 hours apart from systemic antifungal medications (e.g., fluconazole). Can be taken with or without food, but taking with meals may improve tolerance.
1. **Antimicrobial Action**: Competes with pathogens for adhesion sites and nutrients. Produces factors that inhibit growth of pathogens like Clostridioides difficile, Escherichia coli, and Candida albicans. 2. **Anti-Toxin Effects**: Secretes a 54-kDa protease that degrades C. difficile toxins A and B and their intestinal receptors. Binds to bacterial enterotoxins, preventing their action. 3. **Trophic Effects on Mucosa**: Stimulates brush border membrane enzymes (sucrase, maltase, lactase). Enhances intestinal IgA secretion. 4. **Immunomodulation**: Modulates host immune response by increasing secretory IgA, downregulating pro-inflammatory cytokines (TNF-α, IL-6, IL-8), and promoting anti-inflammatory pathways. 5. **Maintenance of Barrier Function**: Helps maintain tight junction integrity, reducing bacterial translocation.
Pregnancy: Category A (as per some regulatory views on probiotics). Limited human data, but considered low risk as it is non-systemic. Use only if potential benefit justifies potential risk. Consult physician.
Driving: No effect. Safe.
| Antifungals (e.g., Fluconazole, Itraconazole, Amphotericin B) | Reduces or abolishes the therapeutic efficacy of S. boulardii by killing the live yeast. | Major |
| Antibiotics (except antifungals) | No negative interaction. S. boulardii is resistant to antibiotics, which is why it's effective for AAD. | None |
| Immunosuppressants (e.g., Tacrolimus, Cyclosporine, Azathioprine, high-dose corticosteroids) | Theoretical increased risk of fungemia. Benefit-risk must be assessed by physician. | Moderate |
Same composition (Saccharomyces boulardii (250mg)), different brands: