What is it?


Saccharomyces boulardii (S. boulardii) is a non-pathogenic yeast microbe with properties that protect it against antibiotics, the body’s internal temperatures, and the acidic environments of the gastrointestinal tract. These properties are not typically observed with bacterial probiotics. (2)(9) S. boulardii was first discovered in lychee and mangosteen fruit and is now cultivated for use in supplements as lyophilized powders, capsules, or liquid beverages. (5

Not to be confused withSaccharomyces cerevisiae (7)

Main uses

Gastrointestinal disorders
Parasitic infections


Labels typically indicate the requirement of refrigeration to prevent loss of potency (7)
Stable at room temperature if kept free from moisture (7)
May have better survival against bile and stomach acid (4)

Dosing & administration

Adverse effects

S. boulardii is generally regarded as safe, however, an increased risk of non-infectious adverse effects (e.g., biliary tract stenoses, fistulas, lienalis-steal syndrome, abdominal hemorrhage, and acute renal failure) has been found in specific groups (e.g., immunocompromised patients, transplant patients or patients with pancreatitis). Rare cases of fungemia associated with S. boulardii have also been reported. (6)(7)(10)



  • S. boulardii is not absorbed, but concentrations stabilize within three days of oral ingestion. (6)(7)


  • Survives in the intestinal tract to reach the colon, its most common target. (6)


  • S. boulardii is not metabolized but rather dies within the competitive environment of the gastrointestinal tract and is excreted. Levels found excreted in the stool can be 100-1000 times smaller than the ingested dose. (6)


  • With a half-life of six hours, S. boulardii populations may clear after three to five days after discontinuation in the feces. (6)(7)
  1. Besirbellioglu, B. A., Ulcay, A., Can, M., Erdem, H., Tanyuksei, M., Avci, I. Y., … Pahsa, A. (2006). Saccharomyces boulardii and infection due to Giardia lamblia. Scandinavian Journal of Infectious Diseases, 38(6-7), 479-481. ()
  2. Czerucka, D., Piche, T., & Rampal, P. (2007). Review article: Yeast as probiotics -Saccharomyces boulardii. Alimentary Pharmacology & Therapeutics, 26(6), 767-778. ()
  3. Garcia Vilela, E., De Lourdes De Abreu Ferrari, M., Oswaldo Da Gama Torres, H., Guerra Pinto, A., Carolina Carneiro Aguirre, A., Paiva Martins, F., … Sales Da Cunha, A. (2008). Influence of Saccharomyces boulardii on the intestinal permeability of patients with Crohn’s disease in remission. Scandinavian Journal of Gastroenterology, 43(7), 842-848. ()
  4. Graff, S., Chaumeil, J. C., Boy, P., Lai-Kuen, R., & Charrueau, C. (2008). Influence of pH conditions on the viability of Saccharomyces boulardii yeast. The Journal of General and Applied Microbiology, 54(4), 221-227. ()
  5. Hu, Y., Qin, H., Zhan, Z., Dun, Y., Zhou, Y., Peng, N., ... & Zhao, S. (2016). Optimization of Saccharomyces boulardii production in solid-state fermentation with response surface methodology. Biotechnology & Biotechnological Equipment, 30(1), 173-179. ()
  6. Kelesidis, T., & Pothoulakis, C. (2012). Efficacy and safety of the probiotic Saccharomyces boulardii for the prevention and therapy of gastrointestinal disorders. Therapeutic Advances in Gastroenterology, 5(2), 111-125. ()
  7. Mcfarland, L. V. (2010). Systematic review and meta-analysis of Saccharomyces boulardii in adult patients. World Journal of Gastroenterology, 16(18), 2202-2222. ()
  8. Szajewska, H., & Kołodziej, M. (2015). Systematic review with meta-analysis: Saccharomyces boulardii in the prevention of antibiotic-associated diarrhoea. Alimentary Pharmacology & Therapeutics,42(7), 793-801. ()
  9. Terciolo, C., Dapoigny, M., & Andre, F. (2019). Beneficial effects of Saccharomyces boulardii CNCM I-745 on clinical disorders associated with intestinal barrier disruption. Clinical and Experimental Gastroenterology, 12, 67-82. ()
  10. Whelan, K., & Myers, C. E. (2010). Safety of probiotics in patients receiving nutritional support: A systematic review of case reports, randomized controlled trials, and nonrandomized trials. The American Journal of Clinical Nutrition, 91(3), 687-703. ()

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