Lactobacillus salivarius (Ligilactobacillus salivarius)
Also called Lactobacillus salivarius, Ligilactobacillus salivarius, L. salivarius, L. salivarius PS2, L. salivarius WB21, L. salivarius Ls-33.
Best grade C across 6 graded outcomes Other Last checked
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The short answer
From 9 sourcesLactobacillus salivarius results depend on the strain. In late pregnancy, strain PS2 cut mastitis after delivery to 25% vs 57% on placebo, and V4II-90 cleared group B strep more often. Strain WB21 tablets gave small gum gains in smokers, while athletes on another strain had no fewer colds. Results do not carry over to other strains.
Every graded outcome on this page
6 rows · line = participants- CGrade CMastitis in the 3 months after deliveryMastitisn 108
- CGrade CUpper respiratory infections in endurance athletesColdsn 54
- CGrade CEczema severity in children (SCORAD)Eczeman 54
- DGrade DGum health (plaque index, pocket depth)Gum healthn 66
- DGrade DGut bacteria in obese adolescentsMetabolic healthn 50
- DGrade DGroup B strep colonisation at 35 weeks of pregnancyGroup B strepn 43
- 3 more graded outcomes, in the evidence chapter
Key facts
- What it is
- A lactic acid bacterium, renamed Ligilactobacillus salivarius; effects are strain-specific28
- Mastitis (108 pregnant women)
- Strain PS2 from week 30: mastitis 25% vs 57% on placebo in women with a past episode2
- Group B strep (43 pregnant women)
- Strain V4II-90: colonisation cleared in 63% vs 27% on placebo8
- Colds in athletes (54 adults)
- 20 billion CFU a day for 16 weeks: no fewer or shorter colds3
What it is
Lactobacillus salivarius (now Ligilactobacillus salivarius) is a lactic acid bacterium; trials tested specific strains such as PS2 and WB21.
Forms, side by side
4 forms named in our sources. The rest show what our data holds, and say plainly where it holds nothing yet.
Lactobacillus salivarius (Ligilactobacillus salivarius) forms compared
4 forms| 4 forms | Strain PS2 (from breast milk) | Strain V4II-90 | Strain WB21 tablets | Strain Ls-33 |
|---|---|---|---|---|
| Absorption in people | No head-to-head human data; milk bacterial counts were lower on PS2 when mastitis occurred.2 | No head-to-head human data.8 | No head-to-head human data.5 | Shifted some gut bacterial ratios; short-chain fatty acids unchanged.7 |
| GI tolerance | No safety problems are reported in the abstract.2 | None of 185 adverse events was judged related to the probiotic.8 | No problems are reported in the abstract.5 | Not detailed in the abstract.7 |
| Studied for | Mastitis after delivery | Group B strep colonisation in pregnancy | Gum health | Metabolic health in obese adolescents (no effect) |
- Strain PS2 (from breast milk)
- Strain V4II-90
- Strain WB21 tablets
- Strain Ls-33
What the human research says
Human trials only, one row per outcome. The form line shows what each trial actually tested. Grades follow our evidence-grading policy.
Trial map
6 graded outcomes, largest study first6 graded outcomes: 3 improved, 1 mixed, 2 no effect. The largest, a 2016 randomized trial of 108 people on mastitis in the 3 months after delivery, found an improvement.
1Mastitis in the 3 months after delivery
Improved · Grade C · RCT, 108 people, 2016
Pregnant women who had infectious mastitis after a previous pregnancy
Dose, result and source| Outcome | Found | People | Study | Who was studied |
|---|---|---|---|---|
| Mastitis in the 3 months after delivery | Improved | 108 | Grade C · RCT, 2016 | Pregnant women who had infectious mastitis after a previous pregnancy |
| Gum health (plaque index, pocket depth) | Mixed | 66 | Grade D · RCT, 2008 | Volunteers without severe periodontitis |
| Upper respiratory infections in endurance athletes | No effect | 54 | Grade C · RCT, 2012 | Highly active men and women in spring training |
| Eczema severity in children (SCORAD) | Improved | 54 | Grade C · RCT, 2012 | Children aged 2 to 14 with moderate to severe atopic dermatitis |
| Gut bacteria in obese adolescents | No effect | 50 | Grade D · RCT, 2013 | Obese adolescents |
| Group B strep colonisation at 35 weeks of pregnancy | Improved | 43 | Grade D · RCT, 2024 | Pregnant women colonised with group B Streptococcus |
Every graded row
6 rowsShowing 6 of 6 outcomes. Human trials only.
CGrade CMastitis in the 3 months after deliveryMastitisFewer casesRCT
n 108 · 2016
Improved Mastitis developed in 25% (14 of 55) on PS2 vs 57% (30 of 53) on placebo, and milk bacterial counts were lower when mastitis occurred.
- Design
- RCT, n = 108, 2016
- Population
- Pregnant women who had infectious mastitis after a previous pregnancy
- Form
- L. salivarius PS2
- Dose
- About 1 billion CFU (9 log10) a day
- Duration
- From about week 30 of pregnancy until delivery
- Source
- Reference 2 · PubMed 26611780 (opens PubMed)
CGrade CUpper respiratory infections in endurance athletesColdsNo effectRCT
n 54 · 2012
No effect The share with at least one week of cold symptoms was 0.58 vs 0.59 on placebo; episode counts, severity, duration, blood immune cells, saliva IgA and lysozyme did not differ.
- Design
- RCT, n = 54, 2012
- Population
- Highly active men and women in spring training
- Form
- L. salivarius (strain not named in the abstract)
- Dose
- 20 billion CFU a day
- Duration
- 16 weeks
- Source
- Reference 3 · PubMed 22645171 (opens PubMed)
CGrade CEczema severity in children (SCORAD)EczemaLower eczema scoresRCT
n 54 · 2012
Improved SCORAD was 27.4 vs 36.3 with prebiotic alone at 8 weeks, more children reached mild disease (52% vs 30%), and medication use fell.
- Design
- RCT, n = 54, 2012
- Population
- Children aged 2 to 14 with moderate to severe atopic dermatitis
- Form
- L. salivarius plus fructo-oligosaccharide vs fructo-oligosaccharide alone
- Dose
- One capsule twice a day
- Duration
- 8 weeks
- Source
- Reference 4 · PubMed 21895621 (opens PubMed)
DGrade DGum health (plaque index, pocket depth)Gum healthGains in smokers onlyRCT
n 66 · 2008
Mixed Both groups improved; only current smokers on WB21 improved plaque index and probing pocket depth more than placebo, with lower salivary lactoferrin.
- Design
- RCT, n = 66, 2008
- Population
- Volunteers without severe periodontitis
- Form
- L. salivarius WB21 tablets with xylitol vs xylitol alone
- Dose
- 6.7 × 10^8 CFU three times a day
- Duration
- 8 weeks
- Source
- Reference 5 · PubMed 18727656 (opens PubMed)
DGrade DGut bacteria in obese adolescentsMetabolic healthNo metabolic effectRCT
n 50 · 2013
No effect The ratio of Bacteroides-Prevotella-Porphyromonas to some Firmicutes rose, but counts of major groups and short-chain fatty acids did not change; earlier reports from the trial found no effect on metabolic syndrome markers.
- Design
- RCT, n = 50, 2013
- Population
- Obese adolescents
- Form
- L. salivarius Ls-33
- Dose
- Not stated in the abstract
- Duration
- 12 weeks
- Source
- Reference 7 · PubMed 23510724 (opens PubMed)
DGrade DGroup B strep colonisation at 35 weeks of pregnancyGroup B strepMore clearanceRCT
n 43 · 2024
Improved Colonisation cleared in 63% (12 participants) on V4II-90 vs 27% (6) on placebo (p = 0.030); none of 185 adverse events was judged related to the probiotic.
- Design
- RCT, n = 43, 2024
- Population
- Pregnant women colonised with group B Streptococcus
- Form
- L. salivarius V4II-90
- Dose
- 1 billion CFU a day
- Duration
- 12 weeks from week 21 to 23
- Source
- Reference 8 · PubMed 38955352 (opens PubMed)
What the numbers add up to
Each point is worked out from the data and the sources numbered on this page, with the arithmetic shown under it. It adds no new data and is not medical advice.
Studied doses
Doses used in research, shown against the official limits. They describe the studies, not a recommendation for you.
Studied doses in research, not advice. These are amounts used in research, not personal advice. Your clinician or pharmacist can say what fits you.
Doses studied in human trials
Interactions and safety
Published interactions only: each row cites a source. No row means none was found in our sources, not that a combination is safe.
Interactions
0 agentsNone found in our sources.
Check with what you take
Kept on this device onlyAdd what you take. We list every interaction our evidence profiles cite between Lactobacillus salivarius and your picks, and between your picks.
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Add a supplement or medicine you take to check it against Lactobacillus salivarius.
Starting from one medicine? The interaction checker rates how serious each pair is, on a curated list of 19 entries for 11 medicines. This cabinet has no severity rating: it lists every interaction row our supplement pages cite.
Who should be careful
4 groups- Weakened immune system or serious illness
- NCCIH says the risk of harmful effects from probiotics is greater in people with severe illnesses or compromised immune systems.1
- Premature infants
- NCCIH notes severe or fatal infections in premature infants given probiotics, and an FDA warning to health care providers.1
How to read the label
What to check on the Supplement Facts panel.
How to read the label
4 checksLook for the strain code
Check the CFU count and use-by date
Follow the storage instructions
ODS notes that some probiotics need to be kept in the refrigerator while others can be stored at room temperature.10
Where to buy Lactobacillus salivarius (Ligilactobacillus salivarius)
Products from brands we partner with that contain Lactobacillus salivarius (Ligilactobacillus salivarius). Check the amount per serving against the doses studied above, and the label for other ingredients.
Lactobacillus salivarius (Ligilactobacillus salivarius) products from partner brands
1 product Paid links · we earn a commission- Physician’s ChoicePhysician’s Choice 60 Billion Probiotic (30 capsules)
1 capsule: 60 billion CFU at expiration from a 10-strain blend of lactobacilli and bifidobacteria (220 mg) that includes L. salivarius Ls-33, plus a 150 mg organic inulin and acacia fiber prebiotic blend; the label lists species only and gives no count per strain (the strain codes are on the brand’s product page); 30 servings
$29.38one-timeChecked Oct 20, 2026
Frequently asked questions
Short answers to common questions; the numbers link to the sources below.
Common questions
7 answersWhat is Lactobacillus salivarius good for?
Does L. salivarius reduce mastitis?
In 108 pregnant women with past mastitis, strain PS2 from week 30 cut mastitis in the 3 months after delivery to 25% vs 57% on placebo.2
Does it help with colds?
No. In 54 endurance athletes, 20 billion CFU a day for 16 weeks did not change how often, how long or how badly they had colds.3
Does it help eczema?
In 60 children with moderate to severe eczema, L. salivarius plus FOS lowered SCORAD scores more than FOS alone after 8 weeks. Only one trial tested this.4
Is L. salivarius safe?
Does L. salivarius interact with medicines?
Sources
9 sources: trial abstracts, NIH fact sheets and reference databases. Numbers in the text link here.
Sources cited on this page
9 sources- 1Probiotics: Usefulness and Safety (last updated August 2019)Fact sheet National Center for Complementary and Integrative Health (NCCIH), 2019 · nccih.nih.gov
- 2Prevention of Infectious Mastitis by Oral Administration of Lactobacillus salivarius PS2 During Late Pregnancy.RCT Clin Infect Dis, 2016 · PMID 26611780
- 3Effects of a Lactobacillus salivarius probiotic intervention on infection, cold symptom duration and severity, and mucosal immunity in endurance athletes.RCT Int J Sport Nutr Exerc Metab, 2012 · PMID 22645171
- 4Lactobacillus salivarius plus fructo-oligosaccharide is superior to fructo-oligosaccharide alone for treating children with moderate to severe atopic dermatitis: a double-blind, randomized, clinical trial of efficacy and safety.RCT Br J Dermatol, 2012 · PMID 21895621
- 5Improvement of periodontal condition by probiotics with Lactobacillus salivarius WB21: a randomized, double-blind, placebo-controlled study.RCT J Clin Periodontol, 2008 · PMID 18727656
- 7Effect of Lactobacillus salivarius Ls-33 on fecal microbiota in obese adolescents.RCT Clin Nutr, 2013 · PMID 23510724
- 8Ligilactobacillus salivarius V4II-90 eradicates Group B Streptococcus colonisation during pregnancy: a randomised, double-blind, placebo-controlled trial.RCT Benef Microbes, 2024 · PMID 38955352
- 9Using Dietary Supplements WiselyFact sheet National Center for Complementary and Integrative Health (NCCIH), 2019 · nccih.nih.gov
- 10Probiotics: Fact Sheet for Consumers (updated November 17, 2025)Fact sheet NIH Office of Dietary Supplements, 2025 · ods.od.nih.gov
What changed
Every dated change to this page: what changed, who made it and why.
Change log
3 entries| Date | Change | Who and why |
|---|---|---|
| safety, label guide, FAQ | Breastfeeding covered (PS2 given only until delivery; not tested while breastfeeding); interaction data noted as limited (none listed by NCCIH or ODS); label guide expanded to four steps with the ODS consumer fact sheet (strain, CFU, use-by date, storage); two FAQs added. No new PMIDs: a 2023–2026 PubMed search found no new L. salivarius trial fitting this page's outcomes beyond the 2024 V4II-90 RCT. | Writer: Kymata Health EditorialTrigger: A–Z page audit |
| where to buy | Added a 10-strain probiotic that includes L. salivarius Ls-33, with its label amounts and the one-time price on the brand’s own page; it is listed as a blend because the label gives no count per strain. | Writer: Kymata Health EditorialTrigger: product listing added |
| all | Initial editorial evidence review. Every PMID checked against NCBI E-utilities esummary (title, year, journal) and each cited abstract read; numbers taken from the abstracts. Rows are strain-specific; the eczema trial is marked as a synbiotic and the athlete and Ls-33 trials as null. Safety from the NCCIH probiotics fact sheet. No product listing: the strains tested are sold mainly in blends. | Writer: Kymata Health EditorialTrigger: new page |
Supplement & Nutrient Encyclopedia. Educational information only; it is not medical advice and does not replace a clinician. Dietary supplements are not intended to diagnose, treat, cure or prevent any disease. Statements about supplements have not been evaluated by the FDA.