Lactobacillus crispatus

Also called L. crispatus, CTV-05, Lactin-V, M247, KT-11.

Best grade B across 6 graded outcomes Other Last checked Oct 21, 2026

The short answer

From 12 sources

The strongest L. crispatus data come from Lactin-V, an investigational vaginal product of strain CTV-05: in 228 women it cut bacterial vaginosis recurrence from 45% to 30% over 12 weeks. Its UTI trial was not significant, and in 338 randomised IVF patients it did not raise pregnancy rates. Oral strains have small trials in vaginosis and HPV clearance.

Every graded outcome on this page

6 rows · line = participants

Grade BRecurrence of bacterial vaginosis after metronidazoleBacterial vaginosisn 228
Grade CBacterial vaginosis and vaginal yeast infection symptomsVaginal healthn 182
Grade CRecurrent urinary tract infection in young womenUrinary tract infectionsn 100
Grade DClearance of high-risk HPV infectionHPVn 62
Grade DImmune cell counts in healthy adultsImmune markersn 20
No effectClinical pregnancy rate in IVF patients with vaginal dysbiosisIVFn 261
3 more graded outcomes, in the evidence chapter

Key facts

What it is: A vaginal-niche Lactobacillus; results belong to named strains (CTV-05, M247, DSM strains, KT-11)^3,5,6
Bacterial vaginosis: Vaginal CTV-05 after metronidazole: recurrence by week 12 was 30% vs 45% on placebo (risk ratio 0.66) in 228 women³
Urinary tract infections: Recurrent UTI in 15% vs 27% on placebo with vaginal CTV-05 (RR 0.5, 95% CI 0.2-1.2; not significant)⁴
Oral strains: Oral capsules improved vaginosis and yeast symptoms in a 182-woman trial; oral M247 raised HPV clearance in 62 women^5,6
Product status: Lactin-V was tested in phase 2 trials as a vaginal product; it is not the same as oral probiotic capsules^3,4

What it is

Lactobacillus crispatus is a lactic acid bacterium that often dominates a healthy vaginal microbiome; trials test named strains.

How it works

Proposed

Proposed: L. crispatus is linked to a Lactobacillus-dominated vaginal community (CST I). In the Lactin-V trials benefit tracked colonisation: CTV-05 was detected in 79% of users at week 12, and high colonisation went with fewer UTIs.^3,4,6

Forms, side by side

3 forms named in our sources. The rest show what our data holds, and say plainly where it holds nothing yet.

Lactobacillus crispatus forms compared

3 forms

Lactobacillus crispatus forms compared: 3 forms by 3 attributes. Empty cells are labelled No data yet, or Not graded in the evidence row.
3 forms	Vaginal live biotherapeutic (Lactin-V, CTV-05)	Oral capsules (DSM strains, M247)	Heat-sterilised cells (KT-11)
Absorption in people	Colonised the vagina: CTV-05 was detected in 79% of users at week 12.³	Oral capsules shifted vaginal measures in the 2023 and 2025 trials.^5,6	Not colonising; non-living cells.⁷
GI tolerance	Adverse events were similar to placebo through 24 weeks.³	The abstracts report no safety problems.^5,6	Two participants were excluded for noncompliance; no safety issues are named in the abstract.⁷
Studied for	Bacterial vaginosis recurrence, recurrent UTI	Vaginosis, yeast symptoms, HPV clearance	Immune markers

Vaginal live biotherapeutic (Lactin-V, CTV-05)
Absorption in people
Colonised the vagina: CTV-05 was detected in 79% of users at week 12.³
GI tolerance
Adverse events were similar to placebo through 24 weeks.³
Studied for
Bacterial vaginosis recurrence, recurrent UTI
Oral capsules (DSM strains, M247)
Absorption in people
Oral capsules shifted vaginal measures in the 2023 and 2025 trials.^5,6
GI tolerance
The abstracts report no safety problems.^5,6
Studied for
Vaginosis, yeast symptoms, HPV clearance
Heat-sterilised cells (KT-11)
Absorption in people
Not colonising; non-living cells.⁷
GI tolerance
Two participants were excluded for noncompliance; no safety issues are named in the abstract.⁷
Studied for
Immune markers

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 first

6 graded outcomes: 4 improved, 2 no effect. The largest, a 2025 randomized trial of 261 people on clinical pregnancy rate in IVF patients with vaginal dysbiosis, found no effect.

By sizeTable

1Clinical pregnancy rate in IVF patients with vaginal dysbiosis

No effect · No-effect grade · RCT, 261 people, 2025

IVF patients in Denmark with abnormal vaginal microbiota (high Fannyhessea vaginae and Gardnerella loads), randomised before embryo transfer

Dose, result and source

Every graded outcome on this page, largest study first
Outcome	Found	People	Study	Who was studied
Clinical pregnancy rate in IVF patients with vaginal dysbiosis	No effect	261	No-effect grade · RCT, 2025	IVF patients in Denmark with abnormal vaginal microbiota (high Fannyhessea vaginae and Gardnerella loads), randomised before embryo transfer
Recurrence of bacterial vaginosis after metronidazole	Improved	228	Grade B · RCT, 2020	Women aged 18-45 who had just completed vaginal metronidazole for bacterial vaginosis
Bacterial vaginosis and vaginal yeast infection symptoms	Improved	182	Grade C · RCT, 2023	Women aged 18-50 with bacterial vaginosis (89) or vulvovaginal candidiasis (93)
Recurrent urinary tract infection in young women	No effect	100	Grade C · RCT, 2011	Premenopausal women with recurrent UTI, after antibiotics for an acute UTI
Clearance of high-risk HPV infection	Improved	62	Grade D · RCT, 2025	Italian women newly diagnosed with HPV and no visible cervical lesions
Immune cell counts in healthy adults	Improved	20	Grade D · RCT, 2025	Healthy Japanese adults (20 analysed)

Every graded row

6 rows

Form tested

Showing 6 of 6 outcomes. Human trials only.

Grade BRecurrence of bacterial vaginosis after metronidazoleBacterial vaginosisFewer recurrencesRCT
n 228 · 2020

Improved Recurrence by week 12 was 30% vs 45% on placebo (risk ratio 0.66, 95% CI 0.44-0.87; P = 0.01) and the benefit held at 24 weeks (RR 0.73). Adverse events did not differ between groups.

Design: RCT, n = 228, 2020
Population: Women aged 18-45 who had just completed vaginal metronidazole for bacterial vaginosis
Form: Lactin-V (L. crispatus CTV-05) vaginal applicator vs placebo, 2:1
Dose: Vaginal dosing for 11 weeks
Duration: 11 weeks, follow-up to 24 weeks
Source: Reference 3 · PubMed 32402161 (opens PubMed)

Grade CBacterial vaginosis and vaginal yeast infection symptomsVaginal healthFewer symptomsRCT
n 182 · 2023

Improved Both oral and vaginal capsules improved Nugent score, discharge, odour and itching in vaginosis, and lowered the main symptom score in yeast infection.

Design: RCT, n = 182, 2023
Population: Women aged 18-50 with bacterial vaginosis (89) or vulvovaginal candidiasis (93)
Form: Oral or vaginal capsules of two or three L. crispatus strains (DSM32717/32720; DSM32720/32718/32716) vs placebo
Dose: Capsules daily (CFU not given in the abstract)
Duration: 3 months
Source: Reference 5 · PubMed 36856121 (opens PubMed)

Grade CRecurrent urinary tract infection in young womenUrinary tract infectionsTrend only, not significantRCT
n 100 · 2011

No effect Recurrent UTI occurred in 15% vs 27% on placebo (RR 0.5, 95% CI 0.2-1.2), which was not statistically significant; in women with high vaginal L. crispatus colonisation the risk was much lower.

Design: RCT, n = 100, 2011
Population: Premenopausal women with recurrent UTI, after antibiotics for an acute UTI
Form: Lactin-V vaginal suppository vs placebo
Dose: Daily for 5 days, then weekly for 10 weeks
Duration: 10 weeks
Source: Reference 4 · PubMed 21498386 (opens PubMed)

Grade DClearance of high-risk HPV infectionHPVMore HPV clearanceRCT
n 62 · 2025

Improved HPV clearance was 60% vs 31.8% in controls, and more women had negative Pap tests (83.3% vs 71.4%).

Design: RCT, n = 62, 2025
Population: Italian women newly diagnosed with HPV and no visible cervical lesions
Form: Oral L. crispatus M247 vs control
Dose: Daily (CFU not given in the abstract)
Duration: 4 months
Source: Reference 6 · PubMed 41125728 (opens PubMed)

Grade DImmune cell counts in healthy adultsImmune markersHigher T cell countsRCT
n 20 · 2025

Improved CD3+ T cell counts were higher than placebo, and fewer cold-like symptoms (notably fatigue) were self-reported; SARS-CoV-2 antibody titres did not change.

Design: RCT, n = 20, 2025
Population: Healthy Japanese adults (20 analysed)
Form: Heat-sterilised L. crispatus KT-11 vs placebo
Dose: Daily (amount in the paper)
Duration: 4 weeks
Source: Reference 7 · PubMed 39889684 (opens PubMed)

No effectClinical pregnancy rate in IVF patients with vaginal dysbiosisIVFNo change in pregnancy rateRCT
n 261 · 2025

No effect Clinical pregnancy rates per embryo transfer were 42% with clindamycin plus Lactin-V, 46% with clindamycin plus placebo and 45% with double placebo; treating the dysbiosis did not improve reproductive outcome.

Design: RCT, n = 261, 2025
Population: IVF patients in Denmark with abnormal vaginal microbiota (high Fannyhessea vaginae and Gardnerella loads), randomised before embryo transfer
Form: Oral clindamycin for 7 days followed by vaginal Lactin-V (L. crispatus CTV-05), vs clindamycin plus placebo, vs double placebo
Dose: Vaginal dosing (amount not stated in the abstract)
Duration: 7 days of clindamycin, then Lactin-V until the pregnancy scan
Source: Reference 10 · PubMed 40467561 (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.

Best evidence is not on store shelves

The only grade B result is for Lactin-V, a vaginal product tested in NIH-funded phase 2 trials; oral strain trials are smaller and mostly maker-linked.^3,4,6,7

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

Doses studied in human trials ranged from 4 weeks of heat-sterilised KT-11 to daily oral capsules for 3-4 months and vaginal Lactin-V for 10-11 weeks.^3,4,5,6,7

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.

What Lactobacillus crispatus meets

2 cited rows

Medicines 2

Lactobacillus crispatus2 medicines · 0 supplements

Supplements and foods 0

No supplement rows in our sources.

Drug label or FDA notice

Interactions

2 agents

Published interactions, grouped by kind
Agent	What the source says	Evidence
Medicines2
Antibioticse.g. any oral antibiotic course	Health Canada's probiotics monograph directs that bacterial probiotics be used at least 2–3 hours before or after antibiotics. In the Lactin-V trials the product was started after a metronidazole course.^1,3	Drug label
Immunosuppressive treatmente.g. long-term corticosteroids	Health Canada lists an immune-compromised condition, including long-term corticosteroid treatment, as a contraindication for probiotics; NCCIH and ODS say harmful effects are more likely in people with compromised immune systems.^1,2,11	Drug label

Check with what you take

Kept on this device only

Add what you take. We list every interaction our evidence profiles cite between Lactobacillus crispatus and your picks, and between your picks.

Add a supplement or medicine

Most cited:

Add a supplement or medicine you take to check it against Lactobacillus crispatus.

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

5 groups

Immune-compromised conditions: Health Canada's probiotic monograph: do not use if you have an immune-compromised condition (for example AIDS, lymphoma, or long-term corticosteroid treatment).¹
Fever or severe gut symptoms: Health Canada: ask a health care practitioner before use if you have fever, vomiting, bloody diarrhoea or severe abdominal pain.¹
Seriously ill people and premature infants: NCCIH reports severe or fatal infections in premature infants given probiotics, which FDA warned health care providers about in 2023, and higher risk in people with serious illness.^2,12
Central lines and intensive care: Lactobacillus bloodstream infection is rare, but risk factors include severe illness, immune suppression, ICU admission and central venous catheters. In ICU patients given probiotics, bacteria in the blood were genetically matched to the capsule strain.^8,9
Pregnancy and breastfeeding: The NCCIH and NIH ODS probiotic fact sheets give no pregnancy- or breastfeeding-specific safety data for probiotic supplements; NCCIH advises consulting a health care provider before using one.^2,11

How to read the label

What to check on the Supplement Facts panel.

How to read the label

2 checks

Vaginal vs oral

The largest trials used a vaginal product (Lactin-V); an oral capsule is a different route with smaller trials.^3,5

Find the strain code

Results belong to CTV-05, M247, the DSM strains or KT-11, not to L. crispatus in general.^3,5,6,7

Frequently asked questions

Short answers to common questions; the numbers link to the sources below.

Common questions

7 answers

Does L. crispatus help bacterial vaginosis?

Vaginal Lactin-V after metronidazole cut 12-week recurrence from 45% to 30% in 228 women. Oral capsules of other strains improved vaginosis scores in a smaller trial.^3,5

Does it help with UTIs?

In 100 women with recurrent UTI, vaginal Lactin-V gave 15% vs 27% recurrence, a difference that was not statistically significant.⁴

Can oral L. crispatus help clear HPV?

One 62-woman trial of oral M247 reported 60% vs 31.8% HPV clearance over 4 months; an author directs the company that markets it.⁶

Does L. crispatus improve IVF success?

Not in the one large trial. In 338 randomised IVF patients with vaginal dysbiosis, clindamycin followed by vaginal Lactin-V gave a 42% clinical pregnancy rate, versus 46% with clindamycin alone and 45% with placebo.¹⁰

Is it safe?

Adverse events matched placebo in the Lactin-V trial. Health Canada says not to use probiotics with an immune-compromised condition, and Lactobacillus bloodstream infections have occurred in very ill people, including those with central lines.^1,2,3,8

Can it be used with antibiotics?

Health Canada's probiotic monograph directs spacing bacterial probiotics at least 2–3 hours from antibiotics. In the Lactin-V vaginosis trial, the product was started after a course of metronidazole.^1,3

What is Lactobacillus crispatus?

A lactic acid bacterium that commonly dominates a healthy vaginal microbiome. Trials test specific strains such as CTV-05 (Lactin-V) and M247.^3,6

Sources

12 sources: trial abstracts, NIH fact sheets and reference databases. Numbers in the text link here.

Sources cited on this page

12 sources

1Probiotics (Natural Health Product monograph, April 24, 2026)Guideline Health Canada, Natural and Non-prescription Health Products Directorate, 2026 · webprod.hc-sc.gc.ca
2Probiotics: Usefulness and SafetyFact sheet National Center for Complementary and Integrative Health (NCCIH), 2019 · nccih.nih.gov
3Randomized Trial of Lactin-V to Prevent Recurrence of Bacterial Vaginosis.RCT N Engl J Med, 2020 · PMID 32402161
4Randomized, placebo-controlled phase 2 trial of a Lactobacillus crispatus probiotic given intravaginally for prevention of recurrent urinary tract infection.RCT Clin Infect Dis, 2011 · PMID 21498386
5Impact of Lactobacillus crispatus-containing oral and vaginal probiotics on vaginal health: a randomised double-blind placebo controlled clinical trial.RCT Benef Microbes, 2023 · PMID 36856121
6Effect of orally administered L. crispatus M247 in favoring HR-HPV clearance and CST shift: results from a randomized, multi-center, placebo-controlled trial.RCT Sci Rep, 2025 · PMID 41125728
7Supplementation with heat-sterilized Lactobacillus crispatus strain KT-11 stimulates the T cell-related immune function of healthy Japanese adults: A pilot randomized, placebo-controlled, double-blind, parallel-group study.RCT Nutr Res, 2025 · PMID 39889684
8Lactobacillus Bacteremia and Probiotics: A Review.Review Microorganisms, 2023 · PMID 37110319
9Genomic and epidemiological evidence of bacterial transmission from probiotic capsule to blood in ICU patients.Observational Nat Med, 2019 · PMID 31700189
10Efficacy of clindamycin and LACTIN-V for in vitro fertilization patients with vaginal dysbiosis: a randomised double-blind, placebo-controlled multicentre trial.RCT Nat Commun, 2025 · PMID 40467561
11Probiotics: Fact Sheet for Health Professionals (updated March 25, 2025)Fact sheet NIH Office of Dietary Supplements, 2025 · ods.od.nih.gov
12Risk of Invasive Disease in Preterm Infants Given Probiotics Formulated to Contain Live Bacteria or YeastSafety communication U.S. Food and Drug Administration, 2023 · fda.gov

What changed

Every dated change to this page: what changed, who made it and why.

Change log

3 entries

Dated changes to this page
Date	Change	Who and why
Oct 21, 2026evidence, interactions, who should avoid, FAQ, summary, sources	Added the 2025 IVF RCT of clindamycin plus Lactin-V (PMID 40467561, null); added antibiotic-spacing and immunosuppressant interactions from the Health Canada monograph, NCCIH and NIH ODS; added a pregnancy and breastfeeding note (NCCIH, ODS); cited the FDA 2023 preterm-infant safety communication; two new FAQs. Fact-checked against the sources; corrected: the IVF trial row now gives the 261 patients analysed rather than the 338 randomised.	Writer: Kymata Health EditorialTrigger: A–Z page audit
Oct 17, 2026all	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. Funding disclosed per study: NIH (2020 Lactin-V), Pharmextracta author (2025 M247), KITII Corporation sponsor (2025 KT-11); the 2011 and 2023 abstracts name no funder. Safety rows use Health Canada and NCCIH only. No product listed in this pass.	Writer: Kymata Health EditorialTrigger: new page
Oct 17, 2026who should avoid	Safety review: added central venous catheter and ICU bloodstream-infection risk (Microorganisms 2023 review; Nat Med 2019 genomic study) and the FDA 2023 preterm-infant warning noted by NCCIH.	Writer: Kymata Health EditorialTrigger: safety review

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.

Lactobacillus crispatus

Medicines 2

Supplements and foods 0

Antibiotics

Immunosuppressive treatment