Treating SIBO With Probiotics

In short: probiotics can help some people with SIBO, but the evidence is modest. A 2017 meta-analysis found that they cleared SIBO more often than no probiotic and reduced abdominal pain, but did not prevent it¹, and a 2024 meta-analysis rated the evidence as low quality². The best-supported option is the yeast Saccharomyces boulardii taken alongside antibiotics⁴. In some people, probiotics may worsen bloating and cause “brain fog”⁶.

This guide covers what the research shows for probiotics in SIBO, the evidence for each strain, when probiotics can make things worse, and how to use them.

Quick answers: probiotics and SIBO

Do probiotics help SIBO?

Often, but the evidence is modest. A 2017 meta-analysis of 18 studies found that probiotics cleared SIBO on breath testing in 63% of patients on average, cleared it more often than no probiotic (relative risk 1.61), lowered breath hydrogen and reduced abdominal pain. They did not reduce stool frequency¹. A 2024 meta-analysis rated the quality of this evidence as low, because the trials were small, varied and at high risk of bias².

Can probiotics make SIBO worse?

In some people, yes. In a 2018 study of 30 people with gas, bloating and brain fog, all were taking probiotics; 68% had SIBO and 77% had D-lactic acidosis. After they stopped probiotics and took antibiotics, brain fog resolved and gut symptoms improved in 77%⁶. One probiotic also raised methane on breath tests in healthy people¹¹.

Can probiotics cause SIBO?

There is no proof that they do. The brain fog study shows an association in a specific group of patients, not cause and effect⁶. Probiotics also have not been shown to prevent SIBO: in the 2017 meta-analysis, people taking them had a lower but not statistically significant rate of developing it¹.

Which probiotics are used for SIBO?

The strains with the most research are the yeast Saccharomyces boulardii (usually alongside antibiotics), the spore-forming Bacillus clausii, and Lactobacillus reuteri for methane overgrowth. The table below summarizes the evidence. Most laboratories ask you to stop probiotics before a breath test.

Evidence by strain

Only the first three were tested in people with SIBO or high breath methane. The others were studied in IBS or functional bloating, which overlap with SIBO but are not the same. See our IBS guide.

Probiotics alongside antibiotics

Most SIBO studies use probiotics together with or after antibiotics, rather than on their own:

• Saccharomyces boulardii with rifaximinRifaximin An antibiotic that is barely absorbed into the bloodstream, so it acts mainly inside the gut. It is a common prescription treatment for SIBO.. In a 2025 Russian randomized study of 108 people with SIBO linked to long-term use of acid-suppressing medicines (PPIsProton pump inhibitor (PPI) A class of acid-reducing medication used for reflux, such as omeprazole. Long-term use lowers stomach acid and is associated with a higher risk of SIBO.), 7 days of rifaximin with S. boulardii left SIBO in 22% four weeks later, compared with 42% after rifaximin alone. Diarrhea resolved significantly only in the combination group⁴. Because it is a yeast, S. boulardii is not killed by antibacterial antibiotics, so the two can be taken together.
• S. boulardii in cirrhosis. In a 2024 randomized, placebo-controlled study in people with advanced liver cirrhosis, 3 months of S. boulardii cleared SIBO in 80% vs. 23% on placebo. Clearing SIBO was linked to fewer complications and better survival in the following year⁵.
• Lactobacillus casei after rifaximin. In a 2013 Italian study of 40 people, monthly rifaximin followed by a week of L. casei improved most symptoms over 6 months. A comparison group given a prebiotic instead did nearly as well, and there was no antibiotic-only group¹².
• Prebiotic fiber with rifaximin. In a 2010 randomized trial of 77 people, adding 5 g a day of partially hydrolyzed guar gum to rifaximin raised the SIBO clearance rate from 62% to 87%¹⁵. See our prebiotics guide.

Spore-forming probiotics

Bacillus species form spores, a protective coat that helps them survive stomach acid and bile before becoming active in the intestine¹⁰. Bacillus clausii is naturally resistant to many antibiotics, which allows it to be taken during antibiotic treatment, according to a 2022 review funded by a manufacturer¹⁰. A 2009 study found that B. clausii alone normalized hydrogen breath tests in people with SIBO at a rate comparable to antibiotics⁷⁸. It was a small, uncontrolled study published as a research letter.

Probiotics for methane overgrowth

Methane overgrowth is caused by archaeaArchaea Single-celled microorganisms that are distinct from bacteria. Methane-producing archaea (methanogens) are responsible for intestinal methanogen overgrowth., mainly Methanobrevibacter smithii, and is linked to constipation. In a 2017 Italian records review of 20 adults with functional constipation and raised breath methane, four weeks of Lactobacillus reuteri DSM 17938 significantly reduced methane production, which disappeared in 11 of them. Hydrogen did not change⁹. There was no control group.

When probiotics can make things worse

Brain fog and D-lactic acidosis

Some lactic acid bacteria produce D-lactic acid, a form the body clears slowly. In the 2018 brain fog study, 30 people with gas, bloating and brain fog all took probiotics. Compared with 8 people without brain fog, they had SIBO more often (68% vs. 28%) and D-lactic acidosis more often (77% vs. 25%). After stopping probiotics and taking antibiotics, brain fog resolved and symptoms improved in 77%⁶. The study was small and did not prove that probiotics caused the problem, but it is a reason to stop probiotics if bloating or brain fog get worse. The same applies to probiotic-rich foods; see our guides to kefir and sauerkraut.

False breath test results

In a 2018 study of 19 healthy volunteers, two weeks of Bifidobacterium infantis 35624 significantly raised methane on a lactuloseLactulose A synthetic sugar the body cannot digest or absorb. As a breath-test substrate it travels the whole small intestine, which also makes false positives more likely. breath test, to levels that would be read as positive for SIBO. Hydrogen did not change¹¹. Stop probiotics before a breath test, following the laboratory’s instructions.

After weight-loss surgery

A 2025 meta-analysis in people who had bariatric surgery found no significant benefit of probiotics or synbiotics for SIBO or gut symptoms³.

How to use probiotics with SIBO

• Choose a strain with evidence for your goal, rather than a high-count blend. S. boulardii alongside antibiotics has the strongest SIBO data⁴.
• Treat the overgrowth first. Probiotics are an add-on to antibiotics or herbal antimicrobials, not a replacement.
• Watch for worse symptoms. Stop if bloating, gas or brain fog increase⁶.
• Stop before testing to avoid misleading breath test results¹¹.
• Address the cause. Probiotics have not been shown to prevent SIBO¹; see our guide to preventing relapse.