Protocols › Probiotics

Probiotics for IBS

Goal: What trials tested for symptoms of irritable bowel syndrome (IBS), and why the certainty of the results is low.

Each protocol describes what studies used, for one goal or for one group of people. It is not advice for you: talk to a doctor before you start a supplement.

Updated 4 Nov 2026
Dose

No dose is confirmed. High-quality trials still need to confirm the strain, dose and duration.[1]

Form

Strains with the higher certainty for overall symptoms in a 2023 review were Escherichia strains (moderate), and Lactobacillus strains and Lactobacillus plantarum 299V (low). For pain they were Saccharomyces cerevisiae I-3856 and Bifidobacterium strains (low).[2]

How long

4 weeks to 6 months in a review of 10 trials.[1]

What studies found

82 trials with 10,332 adults. Only 24 had a low risk of bias in all areas, and the certainty was low to very low for almost all results.[2] A comparison of 81 trials with 9253 people concluded that only some probiotics work, each for particular symptoms.[3]

Ask a doctor first

In 55 trials with more than 7000 people, side effects were not significantly more common with probiotics.[2] Probiotics have been linked to rare blood infections, mostly in people who were severely ill or had a weak immune system.[1]

People with a weak immune system or a serious illness should ask a doctor or pharmacist first.[1]

References

  1. Probiotics: Fact Sheet for Health Professionals. NIH Office of Dietary Supplements, 2025. ods.od.nih.gov
  2. Efficacy of Probiotics in Irritable Bowel Syndrome: Systematic Review and Meta-analysis. Goodoory VC, Khasawneh M, Black CJ, Quigley EMM, Moayyedi P, Ford AC Gastroenterology, 2023. PMID 37541528
  3. Outcome-Specific Efficacy of Different Probiotic Strains and Mixtures in Irritable Bowel Syndrome: A Systematic Review and Network Meta-Analysis. Xie P, Luo M, Deng X, Fan J, Xiong L Nutrients, 2023. PMID 37686889