We use essential cookies (authentication, your saved goals/stack) by default. With your permission we’ll also enable privacy-respecting analytics (Vercel Web Analytics, anonymous load-time metrics) and error-replay diagnostics (Sentry — DOM snapshots only when an error fires) so we can fix bugs faster. Learn more about cookies
Lactobacillus crispatus CTV-05 (LACTIN-V)
NOT a capsule you swallow. L. crispatus CTV-05 (LACTIN-V) is a live biotherapeutic inserted into the vagina with an applicator, and every efficacy trial has used that route — there is no oral evidence at all. Used after a course of vaginal metronidazole, it lowered bacterial-vaginosis recurrence from 45% to 30% in the one large trial, but only in women whose infection actually cleared with the antibiotic first.
What the evidence says
Most L. crispatus CTV-05 studies are mechanism or observational rather than RCTs that measure a clinical effect — keep findings provisional.
Most evidence is from medium-quality randomised trials published 2009–2025 with a typical study size of 61 participants.
Based on 10 studies · 7 RCTs · 650 total participants
Confidence
Moderate confidenceBy outcome
One well-conducted 228-woman phase 2b trial shows a real reduction in bacterial-vaginosis recurrence when used vaginally after antibiotic treatment — but the effect depends on the antibiotic having worked first, there is no phase 3 trial, and the entire evidence base comes from a single development programme.
No trials currently enrolling · 1 completed on ClinicalTrials.gov
1 of the completed trials have posted results
Registered trials show research momentum for L. crispatus CTV-05, not proof of effect — a registration is a plan, and posted results are sponsor-reported, not peer-reviewed. They are never counted toward the evidence rating above.
Browse these trials on ClinicalTrials.govClinicalTrials.gov · as of Sep 2026
Under EU law (Reg. 1924/2006), EFSA reviews whether a specific health claim for L. crispatus CTV-05 meets the evidence standard. These are independent regulatory decisions on claims — not studies, and never counted toward the evidence score above.
Not authorised by EFSA
“Lactobacillus crispatus VPC111 (DSM 16741) Helps to maintain a normal vaginal flora Supports a healthy intestinal flora”
“Lactobacillus crispatus VPC177 (DSM 16743) Helps to maintain a normal vaginal flora Supports a healthy intestinal flora”
“Not authorised” means the specific claim wording did not meet the EU’s evidence standard — often a matter of dossier or phrasing, not proof of no effect. EFSA judges marketing claims and is kept separate from our study-based evidence score.
Source: EU Register of nutrition and health claims (European Commission / EFSA) · register snapshot Feb 2013
Our research database did not respond in time, so the studies and count above cover only our curated set. This refreshes automatically.
Lactobacillus crispatus CTV-05, sold in trials as LACTIN-V, is a vaginally administered live biotherapeutic — a powder delivered by vaginal applicator, never a swallowed capsule. Read every number below in that light: no trial has tested an oral dose of this strain for anything.
Its evidence base is one clinical development programme (Osel, with Cohen and Hemmerling at UCSF) that has run a phase 1 dose-ranging trial, a phase 2a colonisation study, a 228-woman phase 2b trial, and a 45-woman phase 2 trial in South Africa. No phase 3 trial exists.
The phase 2b trial is the headline result: given AFTER a completed 5-day course of vaginal metronidazole gel, it reduced bacterial-vaginosis recurrence by week 12 from 45% to 30% (risk ratio 0.66, 95% CI 0.44-0.87, P=0.01). It is an adjunct to antibiotic treatment, not a treatment in itself.
A later post hoc analysis of that same trial sharpened the picture considerably: the benefit was confined to the 88% of women whose BV had actually cleared after metronidazole (RR 0.56), while in women who had not cleared, the risk ratio was 1.34 (95% CI 0.47-2.23) — no benefit at all.
Colonisation, the mechanism the whole product depends on, is fragile: it is defeated by vaginal intercourse (odds ratio 75.5 for unprotected sex in one trial) and by already having your own endogenous L. crispatus.
The South African phase 2 trial confirmed the strain can establish dominance where it previously did not (41% vs 0% at week 4), though that dominance faded by week 8.
Everything beyond bacterial vaginosis is unproven: a 100-woman recurrent-UTI trial was not statistically significant (RR 0.5, 95% CI 0.2-1.2); an immunology substudy measured lower inflammatory biomarkers but no HIV outcomes; and the single pregnancy study was an uncontrolled observational cohort compared against a historical group, so it cannot show that anything was prevented.
Tolerability across all trials is good, with local genitourinary complaints (discharge, abdominal pain) common but mild and no more frequent than with placebo.
Delivered directly into the vagina, the strain establishes itself on the vaginal mucosa: detected in 79% of treated women at week 12 in the phase 2b trial, and producing an L. crispatus-dominant microbiome in 41% of treated women (vs 0% on placebo) at week 4 in the South African trial. That dominance is transient — it had fallen to 26% by week 8.
Among women who successfully colonised, Atopobium spp. fell from detectable levels to below the limit of detection by day 28, while rising in women who failed to colonise (P=0.04). Gardnerella vaginalis moved in the same direction but not significantly (P=0.19).
In a substudy of highly adherent participants, vaginal IL-1α (P=0.042) and soluble E-cadherin (P=0.035) — a marker of epithelial barrier disruption — were lower 13 weeks after treatment stopped. These are biomarkers only; no infection or transmission outcome was measured.
How L. crispatus CTV-05 works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.
One observational, single-arm study in 61 women at high risk of preterm birth found it tolerable, with 19% reporting solicited adverse events and no serious adverse events. It had no control group, so it says nothing about whether it prevents anything. Use only under obstetric supervision.
Not studied — every trial enrolled otherwise-healthy women. No infection has been reported from any vaginally administered lactobacillus product, which is reassuring but is an absence of reports rather than a demonstrated safety margin: oral probiotics in the same broad class have caused documented bloodstream infection in immunosuppressed and critically ill patients. Use only under clinician supervision.
One trial enrolled sexually active females aged 14-21 and found no safety concern, but colonisation was markedly worse in those having intercourse during the dosing period.
The dedicated trial did not reach statistical significance (RR 0.5, 95% CI 0.2-1.2). Treat this as unproven.
Not a conflict but a prerequisite: every efficacy trial started the product only after a completed 5-day course of vaginal metronidazole. A post hoc analysis found the benefit was confined to women whose BV had actually cleared on that antibiotic (RR 0.56); in those it had not cleared, RR was 1.34 (95% CI 0.47-2.23).
Tip: Reported by 46% in the phase 2a study and 42% in the phase 1 trial; adverse events were evenly distributed between product and placebo arms
Tip: Reported by 46% in the phase 2a study; 90% of all adverse events in that study were mild
Tip: Each reported by about 21% in the phase 2a study, evenly split between product and placebo
Tip: Seen in the small phase 1 trial (3 and 4 of 12 participants); no grade 3 or 4 events occurred in any trial
L. crispatus CTV-05 has an evidence score of 6/10 — moderate evidence based on 12 indexed studies. NOT a capsule you swallow. L. crispatus CTV-05 (LACTIN-V) is a live biotherapeutic inserted into the vagina with an applicator, and every efficacy trial has used that route — there is no oral evidence at all. Used after a course of vaginal metronidazole, it lowered bacterial-vaginosis recurrence from 45% to 30% in the one large trial, but only in women whose infection actually cleared with the antibiotic first. Representative study: PMID 32402161.
The commonly studied dose of L. crispatus CTV-05 is VAGINAL USE ONLY, by applicator: 2 x 10^9 CFU per dose. The phase 2b regimen was one dose daily for 5 days in week 1, then twice weekly for a further 10 weeks — always started after a completed course of vaginal metronidazole gel.. Individual needs vary — start at the lower end of the range and adjust based on how you respond.
Timing is flexible for L. crispatus CTV-05 — consistent daily use matters more than the time of day. It is not swallowed, so meals are irrelevant.
L. crispatus CTV-05 is generally well-tolerated and considered safe for most healthy adults at recommended doses. The most commonly reported side effects are vaginal discharge, abdominal pain, dysuria, urinary frequency or vaginal odour. Use caution if any of these apply to you: Not established for anyone outside the trial populations — otherwise-healthy non-pregnant women aged 14-45; Immunocompromise or immunosuppressive therapy (chemotherapy, transplant medication, high-dose corticosteroids, advanced HIV) — a live organism that no trial has studied in this population; use only under clinician supervision; Critical illness, an indwelling central venous catheter, or a disrupted mucosal barrier — no vaginal-lactobacillus infection has been reported, but oral probiotics have caused documented bloodstream infection in these settings.
VSL#3 / Visbiome
Mostly mechanism / observationalAn 8-strain blend dosed in the hundreds of billions to trillions of CFU per day — roughly 45 to 7,000 times a typical 1-10 billion CFU consumer probiotic — with the largest effect size in the probiotic literature for one narrow use: maintaining remission in chronic pouchitis after ulcerative colitis surgery. It is null for IBS and Crohn's — and since 2016 the brand name no longer reliably identifies the formulation that was studied.
B. lactis (BB-12 / HN019)
Mostly mechanism / observationalThe most-replicated probiotic effect on gut transit — it measurably speeds things up and adds roughly one bowel movement a week in people who are already low. But it is not a constipation cure: the two largest, best-designed trials both missed their primary endpoints, and the honest effect is hours off transit time, not a fix.
L. reuteri DSM 17938
Mostly mechanism / observationalThe best-evidenced probiotic for infant colic — but specifically in breastfed babies, where an individual-participant meta-analysis found a number-needed-to-treat of 2.6. In formula-fed infants the benefit disappears, and the largest single trial actually favoured placebo. Adult claims mostly belong to different L. reuteri strains entirely.
L. rhamnosus GG
Mostly mechanism / observationalOne of the two most-studied probiotic strains, and a case study in why strain-level evidence matters. It has one genuinely strong, guideline-endorsed use — preventing antibiotic-associated diarrhea in children — while its two most-marketed uses, treating stomach bugs and preventing eczema, were both overturned by the largest and best-run trials.
Reviewed by Dr. Baher Al Hakim · Last reviewed July 2026 · evidence from 10 studies · how we score · editorial policy
This information is for educational purposes only. It is not a substitute for professional medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication.
Tap node to isolate • Pinch to zoom • Tap edge for research