NOW Foods Saccharomyces Boulardii provides a clinically proven probiotic yeast that is fundamentally different from bacterial probiotic strains — making it resistant to antibiotics and able to thrive even while antibiotic therapy is ongoing. Saccharomyces boulardii (SB) is one of the most thoroughly studied probiotic organisms, with robust clinical evidence supporting its use for antibiotic-associated diarrhea, traveler's diarrhea, C. difficile infections, and inflammatory bowel conditions. Unlike bacterial probiotics, SB does not need refrigeration and survives stomach acid and bile without special encapsulation. Each capsule delivers 5 billion CFU of live S. boulardii per serving, encapsulated in NOW's GMP-certified facility with verified potency testing. An essential probiotic to take alongside any antibiotic course.