Saccharomyces boulardii

Also known as s boulardii, sacharomyces boulardii, yeast probiotic.

Last reviewed October 9, 2026 · Jump to references

What is Saccharomyces boulardii?

In plain words

Saccharomyces boulardii is a yeast studied for its effects on gut health. It passes through the digestive tract and usually does not stay there permanently. Researchers study it mainly for preventing or shortening certain kinds of diarrhea, including diarrhea linked to antibiotics. Evidence varies by condition, and rare bloodstream infections have occurred, mainly in seriously ill people or those with weakened immune systems or tubes placed in large veins.

Technical definition

Saccharomyces boulardii is a live probiotic yeast classified within Saccharomyces cerevisiae, rather than a peptide or a bacterium. It acts locally in the intestinal lumen through multiple mechanisms, including interactions with microbial toxins, support of epithelial barrier function, and modulation of host immune signaling, rather than binding a single defined receptor. Products are marketed as dietary supplements in the United States and as medicinal products in some countries; regulatory status is product- and jurisdiction-dependent.

Educational information only. This page does not provide medical advice or determine whether a supplement is appropriate for you. Review supplements with a qualified healthcare professional, especially if you take medication, are pregnant, have surgery scheduled, or have a chronic medical condition.

Evidence by use

Each use is rated on its own. There is no single overall effectiveness score.