Evidence Table
SIBO Treatment Trials in One Table
All 47 randomized or controlled trials of SIBO treatments we found, from 1996 to 2026. Each row links to the study on PubMed.
The trials
Showing all 47 trials
Download as CSVClear benefit Some benefit No difference Mixed
How to read the icons and labels
The icon sums up the trial's result for the first-listed treatment against what it was compared with. "Clear benefit" means it did significantly better on the main outcome; "Some benefit" means it did better on some outcomes, for a short time or without a significant difference. It is not a recommendation or a rating of the trial's quality.
SIBO confirmed: every participant had SIBO confirmed by a breath test or a small-intestine fluid culture before treatment. Other trials enrolled people with a condition such as IBS or liver disease and tested for SIBO along the way; they carry a Not all had SIBO label. Weaker designs, such as not randomized, are shown in amber.
| Treatment | Who took part | Result |
|---|---|---|
| Antibiotics Rifaximin vs Low-FODMAP diet 2026 · Randomized, single-blind · Results at 4 weeks · PubMed Read more: Antibiotics guide · Low-FODMAP diet | 100 people Adults with IBS (17% had SIBO) Not all had SIBO | Some benefit Symptom response similar (56% vs 48%). Rifaximin worked faster and was easier to stick to. SIBO cleared in 64% on rifaximin vs 50% on the diet. |
| Other Sodium butyrate Microencapsulated, 1.5 g/day vs Placebo 2026 · Randomized, double-blind · 12 weeks · PubMed | 52 people Adults with type 2 diabetes and IBS Not all had SIBO | Clear benefit Fewer positive breath tests and less pain, diarrhea and bloating. No change on placebo. |
| Herbal Herbal antimicrobials + a biofilm disruptor vs Herbal antimicrobials alone 2025 · Randomized, chart review · 8 weeks · PubMed Read more: Biofilm disruptors | 13 people Adults with SIBO, methane overgrowth or both | Some benefit Hydrogen and methane fell more with the biofilm disruptor. SIBO clearance (60% to 100%) did not differ, and methane overgrowth cleared in no one. |
| Antibiotics Rifamycin SV MMX 388 mg three times a day vs Rifamycin SV MMX 388 mg twice a day 2025 · Randomized, open-label, pilot, dose comparison · 14 days · PubMed Read more: Antibiotics guide | 31 people Adults with SIBO | Some benefit Breath test normalized in 58% overall. Both symptom relief and a normal test in 53% on three daily doses vs 25% on two (full text). |
| Antibiotics Rifaximin; ciprofloxacin; metronidazole vs each other 2025 · Randomized, double-blind · 10 days · PubMed Read more: Antibiotics guide · SIBO and IBS | 97 people Adults with IBS and SIBO | Mixed SIBO cleared in 79% on metronidazole, 59% on rifaximin and 53% on ciprofloxacin. Rifaximin gave the most relief from pain and bloating, with the fewest side effects. |
| Antibiotic add-ons Rifaximin + Saccharomyces boulardii 400 mg and 500 mg, each twice a day vs Rifaximin alone 2025 · Randomized · 7 days · PubMed Read more: Probiotics guide | 108 people Adults with SIBO after long-term acid-reducing (PPI) treatment | Clear benefit SIBO still present 4 weeks later in 22% with S. boulardii vs 42% on rifaximin alone. Diarrhea and symptom scores improved more with the combination. |
| Herbal Herbal antimicrobials, probiotics and prebiotics Added to antibiotics and a low-FODMAP diet; the herbs were an oregano-oil blend, berberine or wormwood vs Antibiotics and low-FODMAP diet 2024 · Not randomized, two hospitals · 3 months · PubMed Read more: Herbal antimicrobials · Berberine · Oregano oil | 179 people Adults with hydrogen or methane SIBO | Some benefit Breath tests normalized about equally (hydrogen 31% vs 38%, methane 47% vs 40%). In methane SIBO, symptoms resolved in 78% vs 60%. Titled a randomized trial, but patients were grouped by the hospital treating them (full text). |
| Antibiotics Rifaximin 400 mg three times a day vs Placebo 2024 · Randomized, double-blind, pilot · 4 weeks · PubMed Read more: Antibiotics guide | 12 people Adults with chronic intestinal pseudo-obstruction (8 of 12 had SIBO) Not all had SIBO | No difference No difference in symptoms. Among those with SIBO, it cleared in 3 of 4 on rifaximin vs 1 of 4 on placebo. |
| Antibiotic add-ons Rifaximin + trimebutine 1,200 mg/day and 600 mg/day vs Rifaximin plus placebo 2024 · Randomized, double-blind · 2 weeks · PubMed Read more: Prokinetics guide | 80 people Adults with functional bloating and SIBO, without constipation | Some benefit SIBO cleared in 34% with trimebutine vs 36% without. Bloating improved more with the combination. |
| Probiotics Saccharomyces boulardii 250 mg twice a day vs Placebo 2024 · Randomized, single-blind · 3 months · PubMed Read more: Probiotics guide | 33 people Adults with decompensated cirrhosis and SIBO | Clear benefit SIBO gone in 80% on S. boulardii vs 23% on placebo. |
| Prokinetics Mosapride; rifaximin; or both vs each other 2023 · Randomized · 2 weeks · PubMed Read more: Prokinetics guide | 83 people Adults with functional dyspepsia and SIBO | No difference SIBO cleared in 17% on mosapride, 32% on rifaximin and 35% on both (no significant difference). |
| Probiotics Saccharomyces boulardii Added to dietary advice vs Dietary advice alone 2023 · Randomized, open-label, pilot · 15 days · PubMed Read more: Probiotics guide · SIBO and IBS | 54 people Adults with diarrhea-type IBS and SIBO | Some benefit Breath hydrogen fell 41% vs 29%, and IBS symptom scores fell 134 vs 93 points. |
| | 79 people Adults with self-reported digestive complaints Not all had SIBO | Some benefit Digestive symptoms improved more than with placebo, but SIBO breath tests did not change. |
| Other Fecal microbiota transplant capsules Once a week vs Placebo capsules 2021 · Randomized · 4 weeks · PubMed | 55 people Adults with IBS and SIBO | Clear benefit Gastrointestinal symptoms improved more than with placebo. No breath-test clearance rate is reported (full text). |
| Probiotics Bacillus subtilis + Enterococcus faecium vs No treatment 2020 · Randomized · 4 weeks · PubMed Read more: Probiotics guide | 50 people Adults with functional bowel disorders after colonoscopy bowel preparation Not all had SIBO | Some benefit SIBO-positive afterwards: 28% on the probiotic vs 56% untreated. Symptom scores were lower. |
| Antibiotic add-ons Metronidazole + Saccharomyces boulardii vs Metronidazole alone; S. boulardii alone 2020 · Open-label, pilot · 2 months · PubMed Read more: Probiotics guide | 40 people Adults with systemic sclerosis and SIBO | Some benefit SIBO cleared in 55% on both, 33% on S. boulardii and 25% on metronidazole. Diarrhea, pain and bloating fell in the S. boulardii groups. |
| Other Ursodeoxycholic acid 100 mg three times a day vs No treatment 2020 · Randomized, pilot · 2 months · PubMed | 24 people Adults with functional dyspepsia and SIBO | Clear benefit Dyspepsia symptoms improved compared with no treatment, and breath methane fell. |
| Antibiotics Rifaximin 1,200 mg/day vs No treatment 2019 · Randomized · 14 days · PubMed Read more: Antibiotics guide | 23 people Children and adults with cystic fibrosis and SIBO | Clear benefit SIBO cleared in 9 of 10 on rifaximin vs 2 of 6 untreated. |
| Antibiotics Rifaximin 550 mg twice a day vs Placebo 2019 · Randomized, double-blind · 2 weeks · PubMed Read more: Antibiotics guide · SIBO and IBS | 50 people Gulf War veterans with IBS without constipation Not all had SIBO | No difference No improvement in symptoms or quality of life. Breath test normalized in 7% on rifaximin vs 22% on placebo (no significant difference). |
| Antibiotics Rifaximin 400 mg three times a day vs Placebo 2018 · Randomized, double-blind, pilot · 2 weeks · PubMed Read more: Antibiotics guide · Methane SIBO | 13 people Adults with chronic constipation who produced methane | Clear benefit Methane fell more on rifaximin. Colon transit normalized in 4 of 6 on rifaximin vs 0 of 7 on placebo, and stools became more frequent. |
| Antibiotics Metronidazole vs Simethicone with activated charcoal 2017 · Randomized, pilot · 10 days · PubMed Read more: Antibiotics guide | 16 people Adults with flatus incontinence and SIBO | Clear benefit Episodes of gas leakage fell by 67% on metronidazole vs 25% on simethicone and charcoal. |
| Probiotics Bifidobacterium triple viable capsules vs Placebo 2016 · Allocation not stated · Not stated in the abstract · PubMed Read more: Probiotics guide | Number not stated Adults with gastric or colorectal cancer and SIBO | Some benefit Reported as effective against SIBO, with fewer gastrointestinal symptoms. The abstract gives no numbers for the treatment comparison. |
| Antibiotics Norfloxacin 800 mg/day vs Placebo 2016 · Randomized, double-blind · 10 days · PubMed Read more: Antibiotics guide · SIBO and IBS | 80 people Adults with IBS, 15 of whom had SIBO on small-intestine fluid culture Not all had SIBO | Clear benefit In the SIBO group, 7 of 8 on norfloxacin no longer met IBS criteria at one month vs 0 of 7 on placebo. All 4 retested on norfloxacin were SIBO-negative. |
| Antibiotic add-ons Antibiotics + lactobacillus probiotic 3 weeks of antibiotics, then 15 days of maintenance antibiotics with the probiotic vs The same antibiotics without the probiotic 2014 · Randomized, double-blind, pilot · Results at 6 months · PubMed Read more: Probiotics guide | 30 people Adults with SIBO and chronic abdominal pain or diarrhea | Clear benefit Breath test negative at 6 months in 93% with the probiotic vs 67% without. Abdominal pain resolved in everyone given the probiotic. |
| Antibiotics Neomycin + rifaximin vs Neomycin plus placebo 2014 · Randomized, double-blind · 14 days · PubMed Read more: Antibiotics guide · Methane SIBO | 31 people Adults with constipation-type IBS and methane on breath | Clear benefit Less constipation, straining and bloating with the combination. Those whose methane cleared had less constipation. |
| Probiotics Six-strain probiotic vs Placebo 2014 · Randomized · 4 weeks · PubMed Read more: Probiotics guide | 53 people Adults with chronic liver disease Not all had SIBO | Clear benefit SIBO disappeared in 24% on the probiotic vs none on placebo. Symptoms improved more; gut permeability and liver tests did not. |
| Probiotics Probiotic Three times a day vs No treatment 2014 · Randomized · 3 months · PubMed Read more: Probiotics guide | 160 people Adults with cirrhosis without overt hepatic encephalopathy Not all had SIBO | Some benefit SIBO fell compared with the start of the trial, and fewer people developed hepatic encephalopathy (7 vs 14). The abstract does not give SIBO rates by group. |
| Probiotics Bifidobacterium longum + Enterococcus faecium Added to standard therapy vs Placebo with standard therapy 2013 · Randomized · 14 days · PubMed Read more: Probiotics guide · Dairy and lactose | 60 people Adults with post-infectious IBS, lactase deficiency and SIBO | Some benefit Overgrowth and lactose digestion improved in 71% on the probiotic; 68% on placebo showed no clear change. |
| Antibiotic add-ons Rifaximin, then Lactobacillus casei Rifaximin for 7 days each month vs Rifaximin, then fructo-oligosaccharides (a prebiotic) 2013 · Randomized · 6 months · PubMed Read more: Probiotics guide · Prebiotics guide | 40 people Adults with SIBO on lactulose and glucose breath tests | No difference Symptoms improved in both groups (83% vs 67% of symptoms improved, no significant difference). |
| Antibiotics Rifaximin 1,200 mg/day vs Placebo 2011 · Randomized, double-blind · 10 days · PubMed Read more: Antibiotics guide | 50 people Adults with celiac disease and persistent symptoms on a gluten-free diet Not all had SIBO | No difference No effect on symptoms, and no difference in the share with SIBO at 2 or 12 weeks. |
| Antibiotics Rifaximin 550 mg three times a day vs Placebo 2011 · Randomized, double-blind · 10 days · PubMed Read more: Antibiotics guide | 75 people Children aged 8 to 18 with chronic abdominal pain (over 90% had an abnormal lactulose breath test) Not all had SIBO | No difference No difference in symptoms. Only 20% of children on rifaximin had a normal breath test afterwards. |
| Probiotics Four-strain probiotic blend vs Metronidazole 500 mg twice a day 2010 · Randomized, pilot · 5 days · PubMed Read more: Probiotics guide | 50 people Adults with chronic bloating and SIBO | Clear benefit Felt better 15 days later: 20 of 25 on the probiotic vs 13 of 25 on metronidazole. Outcome was self-reported improvement; the abstract reports no repeat breath test. |
| Antibiotic add-ons Rifaximin + PHGG 1,200 mg/day and 5 g/day of partially hydrolyzed guar gum vs Rifaximin 1,200 mg/day alone 2010 · Randomized · 10 days · PubMed Read more: Prebiotics guide | 77 people Adults with SIBO on a glucose breath test | Clear benefit SIBO cleared in 85% with guar gum vs 62% on rifaximin alone. |
| Antibiotics Rifaximin 1,200 mg/day vs Metronidazole 750 mg/day 2009 · Randomized · 7 days · PubMed Read more: Antibiotics guide | 142 people Adults with SIBO on a glucose breath test | Clear benefit Breath test normal in 63% on rifaximin vs 44% on metronidazole, with fewer side effects on rifaximin. |
| Antibiotics Rifaximin 1,200 mg/day vs Placebo 2008 · Randomized · 10 days · PubMed Read more: Antibiotics guide · SIBO and rosacea | 52 people Adults with rosacea and SIBO | Clear benefit Of 28 people whose SIBO cleared on rifaximin, skin lesions cleared in 20 and greatly improved in 6. On placebo, 18 of 20 were unchanged and 2 worse. Skin assessors were not blinded to treatment. |
| Antibiotics Oral polymyxin vs Placebo 2007 · Randomized, double-blind · 7 days · PubMed Read more: Antibiotics guide | 25 people Infants in hospital with severe infectious diarrhea Not all had SIBO | No difference Polymyxin did not reduce overgrowth on duodenal culture (8 of 13 before, 10 of 13 after) or clearly improve recovery. |
| Antibiotics Rifaximin 1,600 mg/day vs Rifaximin 1,200 mg/day 2007 · Randomized, dose comparison · 7 days · PubMed Read more: Antibiotics guide | 80 people Adults with SIBO on a glucose breath test | Clear benefit Breath test normal in 80% on 1,600 mg vs 58% on 1,200 mg, with similar side effects. |
| Antibiotics Rifaximin 1,200 mg/day vs Rifaximin 600 or 800 mg/day 2005 · Randomized, dose comparison · 7 days · PubMed Read more: Antibiotics guide | 90 people Adults with SIBO on a glucose breath test | Clear benefit Breath test normal one month later in 60% on 1,200 mg vs 27% on 800 mg and 17% on 600 mg. Side effects were similar. |
| Antibiotics Metronidazole 250 mg three times a day vs Ciprofloxacin 500 mg twice a day 2003 · Randomized · 10 days · PubMed Read more: Antibiotics guide · SIBO and IBD | 29 people Adults with Crohn's disease and SIBO | No difference Breath test normal in 13 of 15 on metronidazole and 14 of 14 on ciprofloxacin (no significant difference). Bloating improved in over 80% in both groups. |
| Antibiotics Neomycin vs Placebo 2003 · Randomized, double-blind · Not stated in the abstract · PubMed Read more: Antibiotics guide · SIBO and IBS | 111 people Adults with IBS (84% had an abnormal lactulose breath test) Not all had SIBO | Clear benefit Composite symptom score improved 35% vs 11% with placebo. Improvement reached 75% in those whose breath test normalized. The abstract does not give the breath-test normalization rate. |
| Probiotics Lactobacillus casei + L. acidophilus vs Placebo 2002 · Randomized, double-blind · 21 days · PubMed Read more: Probiotics guide | 22 people Adults with chronic diarrhea caused by SIBO | Clear benefit Fewer daily stools and lower breath hydrogen than placebo. Other symptoms did not change. |
| Prokinetics Cisapride; or alternating norfloxacin and neomycin vs Placebo 2001 · Randomized · 6 months · PubMed Read more: Prokinetics guide | 34 people Adults with cirrhosis Not all had SIBO | Clear benefit Both cisapride and the antibiotics reduced overgrowth, sped up gut transit and improved liver function. No change on placebo. |
| Prokinetics Cisapride 20 mg twice a day vs No treatment 2000 · Randomized · 7 days · PubMed Read more: Prokinetics guide | 10 people Adults with cirrhosis and gram-negative overgrowth on jejunal fluid culture | Some benefit Overgrowth cleared in 4 of 5 treated patients and persisted in the untreated. |
| Antibiotics Rifaximin 1,200 mg/day vs Placebo 2000 · Randomized, blinded · 7 days · PubMed Read more: Antibiotics guide · SIBO and IBD | 14 people Adults with inactive Crohn's disease of the ileum and SIBO | Some benefit Breath test negative at day 14 in 7 of 7 on rifaximin vs 2 of 7 on placebo. By day 30 it was positive again in everyone. |
| Antibiotics Rifaximin 1,200 mg/day vs Chlortetracycline 1 g/day 2000 · Randomized, double-blind · 7 days · PubMed Read more: Antibiotics guide | 21 people Adults with SIBO on a glucose breath test | Clear benefit Breath test normal in 70% after rifaximin vs 27% after chlortetracycline. Symptoms improved more with rifaximin. |
| Antibiotics Norfloxacin; amoxicillin-clavulanate; Saccharomyces boulardii 800 mg/day; 1,500 mg/day; 1,500 mg/day vs Placebo period (each person received every treatment) 1999 · Randomized, blinded, crossover · 7 days per treatment · PubMed Read more: Antibiotics guide | 10 people Adults with chronic diarrhea caused by SIBO | Clear benefit Both antibiotics cut daily stools compared with placebo. Breath tests turned negative in 3 of 10 people on norfloxacin and 5 of 10 on amoxicillin-clavulanate. |
| Probiotics Lactobacillus fermentum KLD Twice a day vs Placebo 1996 · Randomized, double-blind, crossover · 4 weeks per period · PubMed Read more: Probiotics guide | 17 people Adults with long-standing SIBO | No difference No difference from placebo in breath hydrogen, stools or symptoms. |
No trials match these filters.
Often-quoted studies without a randomized comparison
These studies are widely cited, but nobody in them got a placebo or a randomly assigned comparison treatment. Without that, we can't say whether the treatment did better than something else, so they are listed here without a result icon.
| Treatment | Who took part | Result |
|---|---|---|
| Diet Elemental diet Vivonex Plus, as the only food 2004 · Single group, no comparison · PubMed Read more: Elemental diet guide | 93 people Adults with IBS and an abnormal lactulose breath test | No randomized comparison Breath test normal in 80% after 14 days and 85% after up to 21 days. |
| Herbal Herbal antimicrobial blends vs rifaximin Rifaximin 1,200 mg/day 2014 · Records review, not randomized · PubMed Read more: Herbal antimicrobials · Candibactin | 104 people Adults with SIBO who had a follow-up breath test | No randomized comparison Negative breath test in 46% on herbs vs 34% on rifaximin. As rescue therapy after rifaximin failed, herbs worked in 8 of 14. |
| Diet Palatable elemental diet As the only food 2025 · Single group, no comparison · PubMed Read more: Elemental diet guide | 30 people Adults with SIBO, methane overgrowth or both | No randomized comparison Breath test normal in 73%; all 30 completed the 2-week diet. |
What the trials show
Most trials are small
Half had 50 people or fewer, and only 26 of 47 compared a treatment with a placebo or no treatment.
How we built this tableRifaximin is the most studied
It appears in 20 trials. Higher doses cleared SIBO more often. It beat chlortetracycline and metronidazole in early trials, but a 2025 trial found metronidazole cleared SIBO more often.
Read the antibiotics guideResults vary a lot
Rifaximin cleared SIBO in 9 of 10 people with cystic fibrosis but in only 2 of 10 children with abdominal pain. Different tests and patients make trials hard to compare.
Why breath tests differSome add-ons helped
Adding guar gum fiber or the probiotic yeast S. boulardii to rifaximin cleared SIBO more often in single trials. Adding motility drugs did not.
Read about guar gum (PHGG)Probiotics: mixed results
Some trials found that probiotics cleared SIBO; others found no effect. The strains and patients differed from trial to trial.
Read the probiotics guideHerbal remedies: little evidence
There are almost no controlled trials of herbal antimicrobials. The herbal success rates often quoted come from a records review, listed above.
Read the herbal antimicrobials guideHow we built this table
On November 5, 2026 we searched MEDLINE through Europe PMC for small intestinal bacterial overgrowth, SIBO or methane overgrowth combined with randomized, controlled or placebo, plus targeted searches for individual treatments. We then checked our list against the 30 trials in a 2025 network meta-analysis of SIBO treatments.
A study is included if:
- it was done in people, not animals;
- participants were assigned to two or more groups, at random or as a planned comparison;
- the participants had SIBO, or the study reported a SIBO result for those who did; and
- it was published as a full paper.
Not included:
- studies with only one group, or records reviews where patients were not assigned to groups (the best known are listed above);
- trials that tried to prevent SIBO in people who did not have it, for example probiotics alongside acid-reducing drugs or after gastric bypass;
- results published only as conference abstracts, such as the interim results of a trial comparing berberine with rifaximin. Its study plan is published.
Figures come from each trial's abstract, or from the full text where a row says so. "Cleared" or "normal" means the breath test or fluid culture met that study's own definition of a negative result. Trials used different tests and cut-offs, which is one reason their numbers differ so much.
Missing a trial, or found a mistake? Email [email protected]. See our editorial policy for how we research and check our guides.
Using this table
You can download the full table as a CSV file for a spreadsheet. You are welcome to reuse it; please link to this page as the source.
Related guides
- Compare treatments: antibiotics, herbs and the elemental diet side by side
- SIBO antibiotics, including rifaximin doses and methane combinations
- Herbal antimicrobials and the evidence behind them
- Probiotics for SIBO
- The elemental diet
- Breath tests, and why their results vary