Probiotics

Do probiotics help IBS?

Updated 4 Nov 2026

Short answer

Some strains may help a little, but the evidence is weak. A 2023 review of 82 trials with 10,332 adults with irritable bowel syndrome (IBS) found possible benefits for some strains and mixes. The certainty of the evidence was low to very low for almost all results.[1] No strain, dose or duration is confirmed yet.[2]

What the largest review found

The 2023 review compared probiotics with placebo in 82 randomized trials. Only 24 of them had a low risk of bias in all areas. The certainty of the evidence differed by symptom and by strain:[1]

  • Overall symptoms. Moderate certainty for Escherichia strains. Low certainty for Lactobacillus strains and Lactobacillus plantarum 299V. Very low certainty for mixes, the products LacClean Gold S and Duolac 7s, and Bacillus strains.[1]
  • Abdominal pain. Low certainty for Saccharomyces cerevisiae I-3856 and Bifidobacterium strains. Very low certainty for mixes, Lactobacillus, Saccharomyces and Bacillus strains.[1]
  • Bloating. Very low certainty for mixes and Bacillus strains.[1]
  • Side effects. In 55 trials with more than 7000 people, side effects were not significantly more common with probiotics.[1]

The authors concluded that some mixes or strains may help, but the certainty was low to very low in almost all analyses.[1]

Other reviews

These reviews point in the same direction:

  • A 2023 comparison of 81 trials with 9253 people ranked strains for each symptom. Four strains and five mixes beat placebo on a severity score. Its authors concluded that only some probiotics work, each for particular symptoms, and that the ranking needs confirmation.[3]
  • A 2018 review of 53 trials with 5545 people could not say which strains or mixes work.[4]
  • In a review of 35 trials with 3406 adults, 14 of 29 trials found a statistically significant drop in overall symptoms, and 8 of 34 found a clinically meaningful drop in pain.[2]

Why the results are hard to use

The trials tested many strains and mixes, and they reported different endpoints.[1] A strain may help one symptom and not another. In 10 trials with 877 adults, Bifidobacterium breve, Bifidobacterium longum and Lactobacillus acidophilus lowered pain scores, while Saccharomyces boulardii and several other species did not.[2] For this reason, a result for one product does not necessarily carry over to another.[5] See Does the probiotic strain matter, and how do you choose one?

How long trials lasted

In a review of 10 trials, people took probiotics for 4 weeks to 6 months.[2] In one review of 15 trials, symptoms and pain improved more than with placebo after 8 to 10 weeks.[2]

What is still unknown

High-quality trials still need to confirm the strain, the dose, the duration and the type of IBS that respond, such as IBS with diarrhea or with constipation.[2]

The trial details are in the protocol Probiotics for IBS.[1]

Sources (5)

  1. 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
  2. Probiotics: Fact Sheet for Health Professionals. NIH Office of Dietary Supplements, 2025. ods.od.nih.gov
  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
  4. Systematic review with meta-analysis: the efficacy of prebiotics, probiotics, synbiotics and antibiotics in irritable bowel syndrome. Ford AC, Harris LA, Lacy BE, Quigley EMM, Moayyedi P Aliment Pharmacol Ther, 2018. PMID 30294792
  5. Strain-Specificity and Disease-Specificity of Probiotic Efficacy: A Systematic Review and Meta-Analysis. McFarland LV, Evans CT, Goldstein EJC Front Med (Lausanne), 2018. PMID 29868585

More about probiotics

What are probiotics?Do probiotics change your gut bacteria?Is a higher CFU count better?Which foods contain probiotics?What are probiotics used for?Do probiotics prevent diarrhea from antibiotics and C. difficile?

For education; not medical advice. Talk to a doctor before you start, stop or change a supplement.