Lactobacillus (and Related Genera) and Bifidobacterium Probiotics
Lactobacillus (and its renamed relatives), Bifidobacterium and Bacillus coagulans probiotics, strain by strain: which uses have trial evidence, which do not, and who should ask first.
Content last updated . This page has not been medically reviewed.
What is Lactobacillus and Bifidobacterium probiotics good for?
What the body uses it for, and how strong the evidence is. A normal job in the body is not proof that extra supplements add benefit; each card says which.
Preventing antibiotic-associated diarrhoea
Preliminary or mixedSome probiotics may lower the chance of diarrhoea in people taking antibiotics. NCCIH calls the adult finding tentative; the best strains, durations and amounts are not settled.
Supplements: Result belongs to the strains tested in each trial, not to Lactobacillus or Bifidobacterium as a group.
Preventing Clostridioides difficile diarrhoea after antibiotics
Preliminary or mixedA 2017 analysis found moderate certainty that probiotics reduce C. difficile diarrhoea in people on antibiotics. The AGA found low-certainty support for one named two-strain combination only.
Supplements: Applies to named products in people taking antibiotics; it does not make any Lactobacillus product a treatment.
Irritable bowel syndrome symptoms
Preliminary or mixedReviews suggest possible help for overall symptoms and belly pain, but no firm conclusion on which strains work. The AGA recommends probiotics for IBS only inside clinical trials.
Supplements: Overall certainty was low; no single best strain is named by the sources read.
Constipation
Preliminary or mixedFor adults NCCIH describes some benefit, especially with B. lactis, and a small benefit in older people. In children a 2017 review found no helpful probiotic.
Supplements: Mainly specific Bifidobacterium strains; children's results are mixed.
Infant colic (Lactobacillus reuteri DSM 17938)
Preliminary or mixedA 2018 review found benefit with this one strain, mainly in exclusively breastfed infants. The NHS says probiotic supplements for colic are not recommended.
Supplements: Specific to L. reuteri DSM 17938 and breastfed infants; guidance differs.
Ulcerative colitis support
Preliminary or mixedA 2014 review cited by NCCIH found probiotics, prebiotics or synbiotics could help bring on or keep remission in ulcerative colitis, and no benefit in Crohn's disease. The AGA recommends probiotics for these only within clinical trials.
Supplements: Early evidence; not a substitute for medical treatment.
Immune system effects
Not enough evidenceMarketing often says probiotics boost immunity. The sources read describe immune effects as more likely to be strain-specific and do not show a general benefit.
Supplements: No general immune benefit is shown; claims need strain-specific proof.
Mood and brain effects ('gut-brain axis')
Not enough evidenceMood and anxiety claims for probiotics are not backed by the sources read for this entry.
Supplements: Not verified; marketing claim only on the sources read.
Connected topics
Open a group to see how each topic connects and how strong the evidence is.
Health goals (2)
- Digestive SupportPreliminary or mixed
Specific strains showed possible help in trials for antibiotic-associated diarrhoea, IBS and constipation, but evidence is tentative and no group-wide claim is supported. Results belong to the exact strain and condition studied.
- Gut HealthPreliminary or mixed
'Gut health' is a broad marketing term. Trial support exists only for particular strains and defined problems, and NCCIH says we mostly do not know which probiotics help.
Body systems (3)
- Digestive SystemPreliminary or mixed
Specific strains have tentative support for antibiotic-associated diarrhoea, IBS and constipation. Results belong to the exact strain and condition studied.
- Gut HealthPreliminary or mixed
Probiotics are taken for gut complaints; specific strains have tentative trial support for some of them. Results belong to the exact strain and condition studied.
- Immune SystemDocumented risk
NCCIH says the risk of harm is greater in people with severe illness or weakened immunity. Lactobacillus bloodstream infection is rare but has a higher risk of death in people with central lines, intensive care stays or suppressed immunity.
Body parts (1)
- GutPreliminary or mixed
The gut is where probiotics are meant to act; benefit is tentative and strain-specific. Many products pass through rather than settle.
Functional actions (1)
- Digestive SupportPreliminary or mixed
Tentative trial support for named strains in antibiotic-associated diarrhoea, IBS and constipation. Results belong to the exact strain and condition studied.
Root causes (1)
- Medication Side EffectsPreliminary or mixed
Diarrhoea caused by antibiotics is the best-studied use; some strains reduced it in trials, though NCCIH calls the adult finding tentative.
Conditions & symptoms (7)
- Antibiotic-Associated DiarrheaPreliminary or mixed
A 2017 review of 17 studies found about half the chance of this diarrhoea with probiotics, which the authors called tentative; no benefit shown in older people. Results depend on the strain.
- BacteremiaDocumented risk
Lactobacillus bloodstream infection is infrequent but carries a higher risk of death; risk factors include severe illness, suppressed immunity, intensive care and central lines. NCCIH notes greater harm risk in severely ill people.
- Clostridium Difficile InfectionPreliminary or mixed
NCCIH reports moderate certainty that probiotics lower C. difficile diarrhoea risk in people on antibiotics; best strains and amounts are uncertain. The AGA found low-certainty support for one named combination (L. acidophilus CL1285 + L. casei LBC80R).
- Irritable Bowel SyndromePreliminary or mixed
A 2018 review of 53 studies suggested possible help for overall symptoms and belly pain but no firm conclusion on which strains work; the AGA recommends probiotics for IBS only in clinical trials.
- ConstipationPreliminary or mixed
Some benefit in adults, especially with B. lactis, and a small benefit in older people; children's results mixed.
- Infantile ColicPreliminary or mixed
L. reuteri DSM 17938 helped mainly in exclusively breastfed infants in a 2018 review; the NHS says probiotic supplements for colic are not recommended. Does not apply to other strains.
- Ulcerative ColitisPreliminary or mixed
A 2014 review found possible help with remission; the AGA recommends probiotics only within clinical trials. No benefit found for Crohn disease.
This page is a map. Strain pages go deeper: Lactobacillus rhamnosus GG, Lactobacillus reuteri, the acidophilus group, Bifidobacterium strains, Bacillus coagulans and other spore-formers and the yeast Saccharomyces boulardii.
Why the names look different now
In 2020 researchers proposed splitting the old genus Lactobacillus into 25 genera. [3] Recent papers therefore write Lacticaseibacillus rhamnosus GG [4], Limosilactobacillus reuteri DSM 17938 [5] and Lactiplantibacillus plantarum 299v. [6] Lactobacillus acidophilus kept its old genus name. [3] A strain once called Bifidobacterium infantis 35624 is now listed as B. longum 35624. [6] Older guidelines still use the old names, and so do many labels. See probiotic strains and labels for how to read the full designation (genus, species, strain code).Evidence labels used here
Promising but limited means some trials but few studies or low certainty. Mixed means trials disagree. Insufficient evidence means too little or too weak to say. "CoE" is certainty of evidence as graded by the reviewers. Amounts in trials are study amounts, never advice.Strain-by-strain table
| Strain or combination | Question studied | What the sources found | Label |
|---|---|---|---|
| L. rhamnosus GG | IBS | A 2026 strain-level review of placebo-controlled trials found meta-analyses supporting efficacy for key IBS symptoms. [6] | Promising but limited |
| L. rhamnosus GG | Children's acute gastroenteritis | A US emergency-department trial of 971 children found no better outcomes than placebo. [7] A 2019 meta-analysis of 18 trials found diarrhea lasting about 0.85 day less, with high heterogeneity and methodological limits. [8] | Mixed |
| L. reuteri DSM 17938 | Colic in breastfed infants | Pooled trial data found success about 1.7 times as likely as placebo, with no significant effect in formula-fed infants. [9] NHS (UK) says probiotic supplements for colic are not recommended. [10] | Mixed |
| L. plantarum 299v | IBS; C. difficile treatment | Single IBS trials improved symptoms. [11] The 2026 review found efficacy in meta-analysis. [6] One small trial in C. difficile treatment showed no clear effect, very uncertain. [11] | Promising for IBS; insufficient for C. difficile |
| B. longum 35624 | IBS | Meta-analyses showed efficacy for key IBS symptoms. [6] | Promising but limited |
| Bifidobacterium (mainly B. lactis; B. longum in older adults) | Constipation | NCCIH describes some evidence of benefit in adults and a small benefit in older people. It found no helpful probiotic in a 2017 review of children. [1] | Promising but limited |
| L. acidophilus CL1285 + L. casei LBC80R | Preventing C. difficile diarrhea in people on antibiotics | Risk ratio 0.22 versus placebo (low CoE). [11] | Promising but limited |
| L. acidophilus alone | Children's diarrhea | Four of seven trials used heat-killed preparations. The effect was very uncertain. [11] | Insufficient evidence |
| Bacillus coagulans Unique IS2 and MTCC 5856 | IBS | The 2026 review found efficacy for key symptoms (IS2) and quality of life (MTCC 5856). [6] | Promising but limited |
| E. coli Nissle 1917, L. gasseri BNR17, L. casei Shirota | IBS | Meta-analyses did not demonstrate efficacy. [6] | Insufficient evidence |
Premature infants: hospital decisions only
For preterm, low-birth-weight infants the AGA (US gastroenterology society, 2020) suggests certain products, including some L. reuteri, L. rhamnosus and Bifidobacterium products, to prevent a serious bowel disease called necrotizing enterocolitis. [12] In 2023 the FDA (US) warned that preterm infants given probiotics are at risk of invasive, potentially fatal disease. [13] Nobody should give a probiotic to a premature baby on their own. See probiotics for preterm infants.What the whole picture says
- For IBS the AGA found 55 trials of 44 different probiotics or combinations, most tested in a single small trial. [11]
- Its overall certainty for IBS was low. [11]
- The AGA guideline recommends probiotics for IBS, Crohn's disease and ulcerative colitis only in the context of a clinical trial. [12]
- For children's acute gastroenteritis in North America it suggests against probiotics. [12]
- The sources we read do not name a single best strain for any of these uses, so "best of" claims are marketing, not evidence.
Frequently asked questions
Is Lactobacillus acidophilus a good probiotic?
The species name alone says little. The AGA found that several L. acidophilus diarrhea trials in children used heat-killed material, and the evidence was very uncertain. [11] See the acidophilus group.
Is Bifidobacterium good for constipation?
NCCIH reports some evidence of benefit, especially for B. lactis in adults and B. longum in older adults, but a 2017 review in children found no helpful probiotic. [1]
Is Bacillus coagulans the same as Lactobacillus?
No. It is a different genus, Bacillus, and it appeared in a 2026 IBS review with results that depended on the strain. [6]
Do I need several strains?
Not necessarily. The evidence applies to the exact strain or combination tested, and the AGA graded most combinations as low or very low certainty. [11]
Why did Lactobacillus get renamed, and does it matter for me?
Researchers reclassified the genus in 2020 based on genome sequences. [3] What matters for you is the full designation on the label, so you can compare it with the strain in a study.
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Safety and who should ask first
Lactobacillus bloodstream infection is infrequent, but it carries a higher risk of death. Risk factors include severe underlying disease, suppressed immunity, intensive care and central venous catheters. [15] Ask a clinician or pharmacist before starting any probiotic if you are immunocompromised, seriously ill, have a central line, are pregnant or breastfeeding (see probiotics in pregnancy), or are giving one to a child. See probiotic safety and how medicine interactions work. Interaction lists for these genera were not described in the sources we read, and we found no kidney- or liver-specific guidance (Proper evidence not found in the sources searched), so a pharmacist should check your medicines.
NCCIH says we do not know how much of a probiotic people would need or who would benefit most. [1] The NHS notes that products sold in shops may differ greatly from the ones tested in trials, and labels cannot always be trusted to match the contents. [14] Check quality testing and certifications.
If you have severe or bloody diarrhea, fever or signs of dehydration, get medical care rather than self-treating. The NHS lists diarrhea lasting over 7 days, blood, and dehydration signs as reasons to seek advice. [16]
References
- NCCIH (US National Center for Complementary and Integrative Health). Probiotics: Usefulness and Safety. Read 2026-10-22.
- McFarland LV, Evans CT, Goldstein EJC. Strain-Specificity and Disease-Specificity of Probiotic Efficacy: A Systematic Review and Meta-Analysis. Front Med 2018. PMID 29868585. Read 2026-10-22.
- Zheng J et al. A taxonomic note on the genus Lactobacillus: Description of 23 novel genera, emended description of the genus Lactobacillus Beijerinck 1901, and union of Lactobacillaceae and Leuconostocaceae. PMID 32293557. Read 2026-10-22.
- Lo Vecchio A et al. Benef Microbes 2022. Rotavirus immunisation status affects the efficacy of Lacticaseibacillus rhamnosus GG for the treatment of children with acute diarrhoea: a meta-analysis. PMID 36004717. Read 2026-10-22.
- Dargenio VN et al. Benef Microbes 2022. Use of Limosilactobacillus reuteri DSM 17938 in paediatric gastrointestinal disorders: an updated review. PMID 35212258. Read 2026-10-22.
- Strain-Specific Systematic Review with Meta-Analysis of Probiotics Efficacy in the Treatment of Irritable Bowel Syndrome. PMID 41682832. Read 2026-10-22.
- Schnadower D et al. N Engl J Med 2018. Lactobacillus rhamnosus GG versus Placebo for Acute Gastroenteritis in Children. PMID 30462938. Read 2026-10-22.
- Szajewska H et al. Aliment Pharmacol Ther 2019. Systematic review with meta-analysis: Lactobacillus rhamnosus GG for treating acute gastroenteritis in children - a 2019 update. PMID 31025399. Read 2026-10-22.
- Sung V et al. Pediatrics 2018. Lactobacillus reuteri to Treat Infant Colic: A Meta-analysis. PMID 29279326. Read 2026-10-22.
- NHS (UK). Colic. Read 2026-10-22.
- Preidis GA et al. AGA Technical Review on the Role of Probiotics in the Management of Gastrointestinal Disorders. Gastroenterology 2020 (full text read via PMC8018518). PMID 32531292. Read 2026-10-22.
- Su GL et al. AGA Clinical Practice Guidelines on the Role of Probiotics in the Management of Gastrointestinal Disorders. Gastroenterology 2020 (guideline text read from a hosted copy of the published PDF). PMID 32531291. Read 2026-10-23.
- FDA (US Food and Drug Administration). Risk of Invasive Disease in Preterm Infants Given Probiotics Formulated to Contain Live Bacteria or Yeast (safety communication, 2023). Read 2026-10-23.
- NHS (UK). Probiotics. Page last reviewed 24 November 2022. Read 2026-10-22.
- Kullar R et al. Microorganisms 2023. Lactobacillus Bacteremia and Probiotics: A Review. PMID 37110319. Read 2026-10-22.
- NHS (UK). Diarrhoea and vomiting. Read 2026-10-22.