Protocols › Probiotics

Probiotics for diarrhea from antibiotics

Goal: What trials used to lower the risk of diarrhea during antibiotics. Results depend on the strain and on age.

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

At least 5 billion colony-forming units (CFU, live cells) a day of either strain, in the recommendation of a European pediatric society for children with risk factors.[1] In children, 10 to 20 billion CFU a day of L. rhamnosus GG lowered the risk by 71%.[1] Studies of S. boulardii used various doses and showed no clear link between dose and effect.[1]

Form

A product named by strain. The European society makes recommendations only when at least 2 randomized trials tested a similar, well-defined strain.[2]

When to take

Starting at the same time as the antibiotic. Starting within 2 days of the first dose worked better than starting later.[1]

How long

In trials of L. rhamnosus GG, treatment lasted 10 days to 3 months.[1] A trial of a different, four-strain mix continued until 7 days after the last antibiotic dose.[3]

What studies found

S. boulardii: 21 trials with 4780 people, diarrhea from 20.9% to 8.8% in children and from 17.4% to 8.2% in adults.[4] L. rhamnosus GG: 12 trials with 1499 people, from 22.4% to 12.3%, statistically significant only in children.[1] A trial of about 3000 people aged 65 and older found no benefit from a mix of other strains.[5] These results apply to the strains named.[6]

Ask a doctor first

Probiotics have been linked to rare blood infections, mostly in people who were severely ill or had a weak immune system.[1] Short-term use during antibiotics is likely safe in people without a weak immune system.[7]

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. Probiotics for the Management of Pediatric Gastrointestinal Disorders: Position Paper of the ESPGHAN Special Interest Group on Gut Microbiota and Modifications. Szajewska H, Berni Canani R, Domellöf M, Guarino A, Hojsak I, Indrio F, et al. J Pediatr Gastroenterol Nutr, 2023. PMID 36219218
  3. Probiotics reduce symptoms of antibiotic use in a hospital setting: a randomized dose response study. Ouwehand AC, DongLian C, Weijian X, Stewart M, Ni J, Stewart T, et al. Vaccine, 2014. PMID 24291194
  4. Systematic review with meta-analysis: Saccharomyces boulardii in the prevention of antibiotic-associated diarrhoea. Szajewska H, Kołodziej M Aliment Pharmacol Ther, 2015. PMID 26216624
  5. Lactobacilli and bifidobacteria in the prevention of antibiotic-associated diarrhoea and Clostridium difficile diarrhoea in older inpatients (PLACIDE): a randomised, double-blind, placebo-controlled, multicentre trial. Allen SJ, Wareham K, Wang D, Bradley C, Hutchings H, Harris W, et al. Lancet, 2013. PMID 23932219
  6. 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
  7. Probiotics for the prevention of Clostridioides difficile-associated diarrhea in adults and children. Esmaeilinezhad Z, Ghosh NR, Walsh CM, Steen JP, Burgman AM, Mertz D, et al. Cochrane Database Syst Rev, 2025. PMID 40931979