Saccharomyces boulardii — Uses, Dose and Safety
Want a simple way to cut the chance of diarrhea when taking antibiotics or traveling? Saccharomyces boulardii is a probiotic yeast many doctors recommend for exactly that. It behaves differently from Lactobacillus or Bifidobacterium strains and survives stomach acid well, so it reaches the gut alive.
Clinical studies show S. boulardii reduces antibiotic-associated diarrhea and helps prevent C. difficile recurrence when used alongside standard treatment. It also shortens stool frequency in adults and children with acute infectious diarrhea. The evidence is stronger for prevention of antibiotic-related cases than for chronic conditions like IBS, where results are mixed.
How it helps and when to use
S. boulardii works by blocking harmful bacteria, modulating inflammation, and producing substances that support the gut barrier. Use it if you’re starting antibiotics and want to lower diarrhea risk, if you have traveler’s diarrhea, or if you had a recent C. difficile infection and want to reduce relapse. Some people try it for loose stools linked to inflammatory bowel disease flares, but talk to your gastroenterologist first.
How to take it safely
Typical doses range from 250 mg to 500 mg once or twice daily, depending on the product. Start the probiotic when you begin antibiotics and continue for a few days after finishing them. For C. difficile support, follow the dose used in clinical trials or your doctor’s advice. Keep capsules away from moisture and heat; many brands recommend room temperature storage or refrigeration—check the label.
Don't mix the probiotic in the same mouth as antifungals or give it directly into central venous lines. If you have a severely weakened immune system, a central line, or are critically ill, S. boulardii may cause rare bloodstream infections. In those cases avoid it unless a specialist recommends otherwise.
Side effects are usually mild: gas, bloating, or constipation. If you notice fever, persistent abdominal pain, or worsening symptoms, stop and contact a clinician. For pregnant or breastfeeding people, safety data is limited but generally reassuring; still, ask your provider before starting.
Quality matters. Choose a trusted brand that lists Saccharomyces boulardii lyo or CNCM I-745 on the label and shows colony-forming units (CFUs). Look for third-party testing seals when possible. Avoid products with unclear strain info or no expiration date.
Want a simple plan? If you’ll use antibiotics, pick a reputable S. boulardii product, take it daily while on antibiotics and for 7–14 days after, and check with your doctor if you’re immunocompromised or have a central line. It’s one of the better-supported probiotics for preventing antibiotic-associated diarrhea and cutting C. difficile relapse risk.
For children, many trials used 250 mg once or twice daily for several days; follow pediatric advice and product labeling. S. boulardii doesn’t interact with most drugs, but separate it from antifungals by at least two hours. If you plan to combine probiotics, choose products with clear strains — mixing many strains may not add benefit. If unsure, bring the supplement label to your appointment and ask. Ask before starting.
