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S. boulardii  is a commonly prescribed probiotic that can prevent or improve a number of GI issues. This probiotic also combats bacterial, parasite and fungal infections, and exhibits other important benefits.


Saccharomyces boulardii  is a tropical species of yeast first isolated from lychee and mangosteen fruit in 1923. A French scientist (named Boulard, hence the scientific name of S. boulardii) first isolated this yeast after observing the natives of Southeast Asia chewing on the skin of lychee and mangosteen in an attempt to ward off cholera.

S. boulardii  has been prescribed in the past 30 years for the prevention and treatment of diarrheal diseases caused by bacteria. Evidence suggest that this probiotic may be beneficial for IBD (R) and IBS patients.

Health Benefits of S. boulardii

1) S. boulardii  is Beneficial for the GI Tract


S. boulardii  Prevents and Treats Diarrhea

S. boulardii  is safe and has clear beneficial effects in children who have acute diarrhea (R).

Formula with S. boulardii  shortens the diarrhea duration in infants (R) and allows quicker weight regain than a standard formula (R).

S. boulardii  significantly reduces the frequency and duration of acute diarrhea in children. This probiotic is well-tolerated (R,R,R,R,R,R). It also often reduces the length of ECU and hospital stay in acute infectious gastroenteritis in children (R,R).

S. boulardii  also decreases the duration and frequency of diarrhea, and ameliorates abdominal pain in adults (R), and shortens the hospital stay in patients with acute infectious diarrhea (R).

Some studies report that S. boulardii  is not effective in preventing the development of antibiotic-associated diarrhea (R,R,R,R). However, many studies do, in fact, show that S. boulardii  is effective in reducing the risk of antibiotic-associated diarrhea in both children and adults (R,R,R,R,R,R,R).

S. boulardii  was also found to prevent traveler’s diarrhea, particularly in regions such as North Africa and in the Near-east (R).

S. boulardii  Improves IBS

S. boulardii  improved the cytokine profile, histology, and the quality of life of patients with diarrhea dominant irritable bowel syndrome (IBS-D) (R).

S. boulardii  alone or with mesalazine improved IBS-D symptoms (R).

S. boulardii  improved the quality of life in patients with diarrhea-predominant IBS or mixed-type IBS (R).

One study, however, found no improvement in IBS-D patients after S. boulardii  treatment (R).

S. boulardii  May Alleviate Drug-induced GI Damage

S. boulardii  significantly reduced the numbers of gastric ulcers and the ulceration surface of the gastric mucosa in rats treated with ibuprofen (R).

S. boulardii  May Ameliorate IBD

S. boulardii  can be an effective addition in the treatment of patients with ulcerative colitis (R).

S. boulardii  in association with doxycycline is effective in treating IBD in animal models, in which doxycycline is used to induce remission and long-term probiotic administration helps to prevent the relapses (R).

S. boulardii  treatment limits the infiltration of Th1 cells into the inflamed colon and inhibits proinflammatory cytokine production in mice with IBD (R).

S. boulardii  suppresses colitis and pro-inflammatory cytokine production (R) and decreases tissue NO levels in rats (R).

S. boulardii  reduces inflammation and intestinal colonization by C. albicans in mice with colitis (R).

S. boulardii  is Beneficial in Chron’s Disease

S. boulardii  added to baseline therapy improved intestinal permeability in Chron’s disease (CD) patients, even though complete normalization was not achieved (R).

S. boulardii  in addition to the basic treatment reduced the frequency of bowel movements in CD patients (R).

S. boulardii  Relieves GI Inflammation

S. boulardii  reduces the inflammation and dysfunction of the gastrointestinal tract in mice with intestinal mucositis (R).

S. boulardii  inhibits C. difficile toxin A-associated enteritis and protects against intestinal inflammation in mice (R).

2) S. boulardii  is Beneficial in H. pylori Therapy

S. boulardii  has a positive effect on reducing the colonization of H. pylori in the human gastrointestinal system but is not capable of its eradication when used as single therapy (R).

In patients with H. pylori infection, there is evidence to recommend the use of S. boulardii  along with standard triple therapy as an option for increasing the eradication rates and decreasing overall therapy-related side effects, particularly diarrhea (R,R,R,R,R,R).

S. boulardii  administered in addition to proton pump inhibitor-based triple therapy nonsignificantly lowered the incidence of nausea, vomiting, and abdominal pain and significantly lowered the incidence of stomatitis, constipation, and diarrhea in infected children (R).

S. boulardii  improved anti-H. pylori therapy-associated diarrhea, epigastric discomfort, and treatment tolerability. In addition, S. boulardii  decreased post-treatment dyspepsia symptoms independent of H. pylori status (R).

3) S. boulardii  Combats Bacterial, Parasite and Fungal Infections


S. boulardii  reduces E. coli numbers in children (R).

S. boulardii  increased survival rate, protected against liver damage and inhibited the translocation of bacteria in mice infected with typhoid fever (Salmonella enterica Typhimurium) (R).

S. boulardii  can treat B. hominis infection in children as efficiently as metronidazole (R).

S. boulardii  was effective in treating giardiasis when combined with metronidazole therapy in adult patients (R).

The addition of S. boulardii  to metronidazole in amebiasis significantly decreases the duration of (bloody) diarrhea and enhances clearance of cysts in children (R), and decreases the duration of symptoms and cyst passage in adults (R).

One study, however, found no benefit of S. boulardii  in amebiasis- treatment (R).

S. boulardii  decreases C. albicans adhesion and reduces cytokine-mediated inflammatory host response (R).

Prophylactic S. boulardii  supplementation is as effective as nystatin in reducing fungal colonization and invasive fungal infection, more effective in reducing the incidence of clinical sepsis and the number of sepsis attacks and has a favorable effect on feeding intolerance in very low birth weight infants(R).

4) S. boulardii  Boosts the Immune Response


S. boulardii  enhances the immune response in pediatric acute gastroenteritis (R).

Oral treatment with viable or heat-killed cells of S. boulardii  maintains the intestinal integrity and modulates the immune system in mice, preventing bacterial translocation and intestinal lesions (R).

5) S. boulardii  Increases Feeding Tolerance in Infants

Prophylactic supplementation of S. boulardii  improved weight gain, improved feeding tolerance, and had no adverse effects in preterm infants >30 weeks old (R).

Orally administered S. boulardii  reduces feeding intolerance and clinical sepsis in very-low-birth-weight (VLBW) infants (R).

6) S. boulardii  May Help Prevent Cardiovascular Disease


Daily supplementation with S. boulardii  lowered remnant lipoprotein in hypercholesterolemic adults, a predictive biomarker and potential therapeutic target in the treatment and prevention of coronary artery disease (R).

7) S. boulardii  May be Beneficial in Diabetes and Obesity

S. boulardii  induced dramatic changes in gut microbiota, reduced body weight and fat mass and improved hepatic steatosis and inflammatory tone in obese and type 2 diabetic mice (R).

8) S. boulardii  May Improve Liver Health


S. boulardii  promotes liver function and slows down the progress of liver fibrosis in rats (R).

S. boulardii  effectively prevents liver injury induced by Salmonella Enteritidis infection in mice (R).

S. boulardii  ameliorates intestinal injury and the accompanying liver inflammation by supporting the antioxidant state of the tissues and by inhibiting the recruitment of neutrophils (R).

9) S. boulardii  May be Beneficial in HIV Patients

Treatment with S. boulardii  decreases microbial translocation (LBP) and inflammation parameters in HIV-1-infected patients with long-term virologic suppression (R).


  • S. boulardii  decreases pro-inflammatory cytokines TNF-α (R,R,R,R,R), IL-1β (R,R,R) and IL-6 (R,R).
  • S. boulardii  decreases IL-8 (R,R,R,R,R) (a study where IL-8 was increased: R).
  • S. boulardii  increases the anti-inflammatory cytokine IL-10 (R,R,R) (in some tissues IL-10 may be decreased: R).
  • S. boulardii  can both increase (R) and decrease (R) TGF-beta.
  • S. boulardii  can both decrease (R) and increases IFN-γ (R,R).
  • S. boulardii  increases IgA (R,R), can increase CD8 lymphocytes (R) and TLR2 and TLR4 (R).
  • S. boulardii  increases GSH (R).
  • S. boulardii  decreases CXCL1 (R), CRP (R) and NF-kappaB (R,R).
  • S. boulardii  can both increase and decreases PPAR-γ (R,R).
  • S. boulardii  decreases COL1A1, αSMA, AST, ALT and MDA (R).


S. boulardii  is safe for use in otherwise healthy populations and was even shown to be safe in patients infected with HIV-1  (R).

However, fungemia is a rare but serious complication of treatment with S. boulardii, and this probiotic should be taken with care or avoided in immunocompromised patients (R).

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  • John

    Avoid it, after a week of use, developed fungal infections on arms, legs and chest!

  • Leslie Montano

    I recently heard of this for the treatment of eczema by a particular individual on their podcast. Any studies or information to back that claim up?

  • Roz

    Is it safe to keep taking boulardii or should a person stop after a period of time ?

  • Lauren Gordon

    Is it safe to take Saccharomyces Boulardii (S. boulardii) if you have myalgic encephalomyelitis?

  • Ted Hu

    yes, one may be allergic to yeast probiotics right away or after a period of use as was my case. After a year of use, suddenly developed moist micro scarring skin allergies.

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