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.

What is Saccharomyces boulardii?

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 suggests that this probiotic may be beneficial for IBD [1] and IBS patients.

Health Benefits

1) Beneficial for the GI Tract

Prevents and Treats Diarrhea

S. boulardii is safe and has clear beneficial effects on children who have acute diarrhea [2].

Formula with S. boulardii shortens the diarrhea duration in infants [3] and allows quicker weight regain than a standard formula [4].

S. boulardii significantly reduces the frequency and duration of acute diarrhea in children. This probiotic is well-tolerated [5, 6, 7, 8, 9, 10]. It also often reduces the length of ECU and hospital stay in acute infectious gastroenteritis in children [11, 12].

S. boulardii also decreases the duration and frequency of diarrhea, and ameliorates abdominal pain in adults [13], and shortens the hospital stay in patients with acute infectious diarrhea [14].

Some studies report that S. boulardii is not effective in preventing the development of antibiotic-associated diarrhea [15, 16, 17, 18]. 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 [19, 20, 21, 22, 23, 24, 25].

S. boulardii was also found to prevent traveler’s diarrhea, particularly in regions such as North Africa and in the Near-east [26].

Improves IBS

S. boulardii improved the cytokine profile, histology, and the quality of life of patients with diarrhea dominant irritable bowel syndrome (IBS-D) [27].

S. boulardii alone or with mesalazine improved IBS-D symptoms [28].

S. boulardii improved the quality of life in patients with diarrhea-predominant IBS or mixed-type IBS [29].

One study, however, found no improvement in IBS-D patients after S. boulardii treatment [30].

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 [31].

May Ameliorate IBD

S. boulardii can be an effective addition in the treatment of patients with ulcerative colitis [32].

In association with doxycycline, it 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 [33].

S. boulardii treatment limits the infiltration of Th1 cells into the inflamed colon and inhibits proinflammatory cytokine production in mice with IBD [34].

It suppresses colitis and pro-inflammatory cytokine production [35] and decreases tissue NO levels in rats [36].

S. boulardii reduces inflammation and intestinal colonization by C. albicans in mice with colitis [37].

Is Beneficial in Crohn’s Disease

S. boulardii added to baseline therapy improved intestinal permeability in Crohn’s disease (CD) patients, even though complete normalization was not achieved [38].

In addition to the basic treatment, it reduced the frequency of bowel movements in CD patients [39].

Relieves GI Inflammation

S. boulardii reduces the inflammation and dysfunction of the gastrointestinal tract in mice with intestinal mucositis [40].

S. boulardii inhibits C. difficile toxin A-associated enteritis and protects against intestinal inflammation in mice [41].

2) 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 [42].

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 [43, 44, 45, 46, 47, 48].

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 [49].

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 [50].

3) Combats Bacterial, Parasite and Fungal Infections

S. boulardii reduces E. coli numbers in children [51].

S. boulardii increased survival rate, protected against liver damage and inhibited the translocation of bacteria in mice infected with typhoid fever (Salmonella enterica Typhimurium) [52].

S. boulardii can treat B. hominis infection in children as efficiently as metronidazole [53].

S. boulardii was effective in treating giardiasis when combined with metronidazole therapy in adult patients [54].

The addition of S. boulardii to metronidazole in amebiasis significantly decreases the duration of (bloody) diarrhea and enhances clearance of cysts in children [55], and decreases the duration of symptoms and cyst passage in adults [56].

One study, however, found no benefit of S. boulardii in amebiasis- treatment [57].

S. boulardii decreases C. albicans adhesion and reduces cytokine-mediated inflammatory host response [58].

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 [59].

4) Boosts the Immune Response



S. boulardii enhances the immune response in pediatric acute gastroenteritis [60].

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 [61].

5) Increases Feeding Tolerance in Infants

Prophylactic supplementation of S. boulardii improved weight gain and feeding tolerance and had no adverse effects in preterm infants >30 weeks old [62].

Orally administered S. boulardii reduces feeding intolerance and clinical sepsis in very-low-birth-weight (VLBW) infants [63].

6) 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 [64].

7) 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 [65].

8) May Improve Liver Health

S. boulardii promotes liver function and slows down the progress of liver fibrosis in rats [66].

S. boulardii effectively prevents liver injury induced by Salmonella Enteritidis infection in mice [67].

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 [68].

9) 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 [69].


  • Decreases pro-inflammatory cytokines TNF-α [40,35,70,37,27], IL-1β [40,41,71] and IL-6 [70,69].
  • Decreases IL-8 [35, 41, 71, 27, 58] [a study where IL-8 was increased: 70].
  • Increases the anti-inflammatory cytokine IL-10 [61, 27, 72] [in some tissues IL-10 may be decreased: 72].
  • Can both increase [73] and decrease [66] TGF-beta.
  • Can both decrease [37] and increases IFN-γ [72].
  • Increases IgA [61, 60], can increase CD8 lymphocytes [60] and TLR2 and TLR4 [37].
  • Increases GSH [68].
  • Decreases CXCL1 [40], CRP [60] and NF-kappaB [35, 71].
  • Can both increase and decreases PPAR-γ [35, 1].
  • Decreases COL1A1, αSMA, AST, ALT, and MDA [66].


S. boulardii is safe for use in otherwise healthy populations and was even shown to be safe in patients infected with HIV-1  [69].

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 [74].


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About the Author

Biljana Novkovic - PHD (ECOLOGICAL GENETICS) - Writer at Selfhacked

Dr. Biljana Novkovic, PhD

PhD (Ecological Genetics)

Biljana received her PhD from Hokkaido University.

Before joining SelfHacked, she was a research scientist with extensive field and laboratory experience. She spent 4 years reviewing the scientific literature on supplements, lab tests and other areas of health sciences. She is passionate about releasing the most accurate science & health information available on topics, and she's meticulous when writing and reviewing articles to make sure the science is sound. She believes that SelfHacked has the best science that is also layperson-friendly on the web.

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