Saccharomyces boulardii (S. boulardii) is a yeast that occurs naturally in the human digestive system. Some studies suggest that taking S. boulardii as a probiotic may benefit certain conditions, such as traveler’s diarrhea.

S. boulardii may also help protect a person’s gut flora while they take antibiotics, or help it to recover afterward. However, research on probiotics is still in its early stages.

This article provides an overview of the uses and benefits of S. boulardii probiotics.

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Saccharomyces boulardii is a yeast that scientists discovered in the peels of certain tropical fruit. Its probiotic strain, S. boulardii CNCM I-745, was the first yeast that scientists studied as a probiotic for human medicine. Probiotics are supplements that contain live microbes that may have health benefits.

S. boulardii CNCM I-745 has some properties that make it potentially useful as a probiotic. It can survive the harsh conditions of the stomach. Acidic environments, high temperatures, bile, and digestive enzymes do not deactivate it, which means it can reach the intestines alive.

There is some evidence that S. boulardii may have benefits for several digestive conditions. S. boulardii may help with:

Traveler’s diarrhea

A 2019 review found that, in comparison with two other probiotics, S. boulardii is significantly more effective for preventing traveler’s diarrhea.

Traveler’s diarrhea occurs when a person ingests viruses, bacteria, or protozoa in food or drink while traveling.

Antibiotic-associated diarrhea

Antibiotics can disrupt gut flora, which may lead to diarrhea during treatment. In some cases, antibiotics can also lead to dysbiosis, which is when a person’s gut flora becomes imbalanced.

According to a 2020 review, there is evidence that S. boulardii may help prevent antibiotic-associated diarrhea and help restore a person’s gut flora after treatment. As it is a yeast, antibiotics do not kill it, which means a person can take antibiotics and S. boulardii at the same time.

Helicobacter pylori

H. pylori is a bacterium that many people have in their digestive tract. In some cases, it can cause indigestion and stomach ulcers.

A 2019 systematic review and meta-analysis looked at data from 18 previous trials on the use of S. boulardii for treating this infection. In comparison with the standard treatment alone, which is antibiotics, a combination of S. boulardii and antibiotics was more effective in eradicating the bacteria.

People taking S. boulardii also have lower rates of side effects from treatment, particularly diarrhea and constipation. Fewer people also stopped their treatment in comparison to people who only took antibiotics.

Many of the potential uses of S. boulardii need more research. This includes:

Clostridium difficile

C. difficile is a bacterium that causes diarrhea and can be potentially life threatening. It often occurs in people who have received antibiotics in hospital settings.

A 2020 review summarized the research so far on the use of S. boulardii for C. difficile. Many of the studies have involved a low number of participants or had inconclusive results.

Inflammatory bowel disease

A 2019 animal study in mice tested S. boulardii‘s effect on inflammatory bowel disease (IBD). IBD refers to a group of conditions that cause inflammation and pain in the digestive tract.

The probiotic had an anti-inflammatory effect in the mice, which may mean it has potential as a complementary therapy in humans with IBD. Human clinical trials are necessary to test this.

Irritable bowel syndrome

Irritable bowel syndrome (IBS) refers to a group of digestive symptoms including diarrhea, constipation, and cramping. There may be several underlying causes for IBS, but scientists are still learning about this.

The 2020 review notes that in previous research, people with IBS who took S. boulardii reported better quality of life than people who took a placebo. However, they did not report a change in the frequency or consistency of bowel movements.

Other studies, including some animal studies, have shown better results regarding symptom reduction, but overall, the results have been mixed.


Similarly to S. boulardii, Candida albicans is a type of yeast that occurs in the human digestive tract. However, it is opportunistic, meaning that if it gets an opportunity to grow and spread, it will. This can happen if a person takes antibiotics, or if they have a weakened immune system.

Previous laboratory studies have shown that S. boulardii inhibits the growth of C. albicans and reduces the production of biofilm, which can protect microbes from harm. More studies with humans are necessary to confirm this benefit.


Dyslipidemia is when a person has imbalanced lipids in their blood, including cholesterol and triglycerides.

A 2019 study in hamsters showed that S. boulardii probiotics may be a safe and beneficial approach to lower cholesterol, with or without traditional treatment. However, animal studies do not always show what will happen in humans. More research is necessary.

There is not much research on S. boulardii probiotics and their side effects. Some studies have found it caused constipation in those undergoing treatment for C. difficile, but otherwise, there is little information.

Other probiotics can cause side effects such as bloating and gas.

S. boulardii probiotics are generally safe. However, people should always check with a doctor before using any new supplement. Although safe for many, probiotics are not suitable for everyone.

People with critical illnesses or weakened immune systems may be vulnerable to fungal infections if they take S. boulardii probiotics.

If a person has severe disease in the intestines, or a catheter inside the body, it is also possible for yeast to get into the bloodstream. This condition is known as Saccharomyces fungemia, and it is a medical emergency.

Rarely, a person may experience an allergic reaction to S. boulardii probiotics.

Under the right circumstances, any live microbe can carry risks. Because of this, anyone thinking about trying S. boulardii should consult a doctor first to ensure it is safe.

S. boulardii is not a proven treatment for any medical condition. Even in cases where research suggests it helps, it is often a supportive or complementary therapy, as it is in H. pylori treatment.

People should speak with a doctor if they want to add S. boulardii to their treatment plan. They should also consult a doctor if they have digestive symptoms and do not yet have a diagnosis.

S. boulardii is a type of yeast that may have benefits for several digestive conditions. It may help to protect a person’s gut flora during antibiotic treatment, and aid in restoring the microbiome afterward. It may also help to treat certain infections, such as those that cause traveler’s diarrhea, or H. pylori.

However, many of the studies on S. boulardii have limitations, and none so far have proven it works as a standalone treatment for any medical condition. Additionally, it is not a safe supplement for everyone. Check with a doctor before trying S. boulardii probiotics.