L. rhamnosus GR-1 and L. reuteri RC-14
Also called GR-1 and RC-14, Lactobacillus rhamnosus GR-1, Lactobacillus reuteri RC-14, Lacticaseibacillus rhamnosus GR-1, Limosilactobacillus reuteri RC-14, Lactobacillus fermentum RC-14.
Best grade C across 15 graded outcomes Other Last checked
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The short answer
From 17 sourcesThis two-strain probiotic is the most studied oral option for vaginal health. Added to antibiotics, it raised bacterial vaginosis clearance rates in trials in Nigeria and Brazil, but not in a 2021 Chinese trial, and it did not change vaginal flora in pregnancy. Against recurrent urinary infections it fell short of a daily antibiotic.
Quick pick
From a partner brand · paid link
Jarrow Formulas Fem Dophilus, 5 Billion CFU, 30 Capsules
from HerbsPro
Label: 1 capsule: 5 billion CFU total of L. rhamnosus GR-1 and L. reuteri RC-14 (guaranteed when refrigerated and within the best-used-by date).
Best for value: the lowest one-time price of the 2 partner products on this page ($20.36, checked Oct 15, 2026).
Every graded outcome on this page
15 rows · line = participants- CGrade CReturn to balanced vaginal flora (oral probiotic alone)Bacterial vaginosisn 544
- CGrade CRecurrent urinary tract infections vs antibiotic prophylaxisUrinary infectionsn 252
- CGrade CBacterial vaginosis clearance with metronidazoleBacterial vaginosisn 125
- CGrade CGroup B strep colonisation late in pregnancyPregnancyn 110
- CGrade CVaginal flora after menopauseVaginal floran 72
- CGrade CVaginal flora in healthy womenVaginal floran 64
- CGrade CBacterial vaginosis clearance with tinidazoleBacterial vaginosisn 64
- CGrade CVaginal yeast infection with fluconazoleYeast infectionn 55
- DGrade DHigh-risk HPV clearance and cervical smear qualityHPVn 121
- DGrade DBacterial vaginosis in women with HIVBacterial vaginosisn 65
- DGrade DCD4 count and immune markers in HIVImmune functionn 55
- ∅No effectBacterial vaginosis in early pregnancyPregnancyn 304
- ∅No effectUrinary tract infections after spinal cord injuryUrinary infectionsn 207
- ∅No effectGroup B strep colonisation in pregnancy (pilot)Pregnancyn 139
- ∅No effectBacterial vaginosis clearance with vaginal metronidazoleBacterial vaginosisn 126
Key facts
- What it is
- Lacticaseibacillus rhamnosus GR-1 plus Limosilactobacillus reuteri RC-14 (first published as L. fermentum RC-14), usually in one capsule134
- Strain matters
- Health Canada requires the strain designation on probiotic labels; NCCIH notes one strain's effects do not carry over to others12
- With antibiotics for vaginosis
- Cleared in 88% vs 40% with metronidazole (106 analysed) and 87.5% vs 50.0% with tinidazole (64 women)45
- Null trials
- No effect on vaginosis in pregnancy (238 analysed), on clearance in a Chinese trial (126) or on UTIs after spinal cord injury (207)101314
- Who should not use it
- Health Canada: not for people with an immune-compromised condition1
What it is
GR-1 and RC-14 are two Lactobacillus strains sold together in oral capsules aimed at vaginal and urinary health.
Forms
Form
| Form | Elemental % | Absorption (human data) | GI tolerance | Studied for |
|---|---|---|---|---|
| Oral capsules with both strains | Varies1Not applicable (dose in colony-forming units, CFU) | Not absorbed; the strains are meant to reach the vagina. Vaginal lactobacilli rose in some trials, but a 2021 trial rarely detected the strains.413 | No adverse effects in 64 healthy women over 60 days; no serious adverse effects in the 2021 Chinese trial.313 | Bacterial vaginosis with antibiotics, yeast infection with fluconazole, postmenopausal flora, recurrent UTIs, Group B strep in pregnancy |
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
15 graded outcomes, largest study first15 graded outcomes: 7 improved, 2 mixed, 6 no effect. The largest, a 2013 randomized trial of 544 people on return to balanced vaginal flora (oral probiotic alone), found an improvement.
1Return to balanced vaginal flora (oral probiotic alone)
Improved · Grade C · RCT, 544 people, 2013
544 Croatian women diagnosed with vaginal infection in a bacterial vaginosis trial (395 probiotic, 149 placebo)
Dose, result and source| Outcome | Found | People | Study | Who was studied |
|---|---|---|---|---|
| Return to balanced vaginal flora (oral probiotic alone) | Improved | 544 | Grade C · RCT, 2013 | 544 Croatian women diagnosed with vaginal infection in a bacterial vaginosis trial (395 probiotic, 149 placebo) |
| Bacterial vaginosis in early pregnancy | No effect | 304 | No-effect grade · RCT, 2020 | 304 pregnant women recruited at 9 to 14 weeks in the UK; 238 analysed |
| Recurrent urinary tract infections vs antibiotic prophylaxis | Mixed | 252 | Grade C · RCT, 2012 | 252 postmenopausal women with recurrent UTIs |
| Urinary tract infections after spinal cord injury | No effect | 207 | No-effect grade · RCT, 2019 | 207 people with spinal cord injury and neurogenic bladder in Australia |
| Group B strep colonisation in pregnancy (pilot) | No effect | 139 | No-effect grade · Pilot RCT, 2021 | 139 pregnant midwifery clients in Toronto; 113 analysed |
| Bacterial vaginosis clearance with vaginal metronidazole | No effect | 126 | No-effect grade · RCT, 2021 | 126 Chinese women with bacterial vaginosis |
| Bacterial vaginosis clearance with metronidazole | Improved | 125 | Grade C · RCT, 2006 | 125 premenopausal Nigerian women with bacterial vaginosis; 106 returned at day 30 |
| High-risk HPV clearance and cervical smear quality | No effect | 121 | Grade D · RCT, 2019 | 121 Taiwanese women with genital high-risk HPV infection (62 probiotic, 59 placebo) |
| Group B strep colonisation late in pregnancy | Improved | 110 | Grade C · RCT, 2016 | 110 GBS-positive pregnant women at 35 to 37 weeks in Taiwan; 99 completed |
| Vaginal flora after menopause | Improved | 72 | Grade C · RCT, 2008 | 72 postmenopausal women with intermediate Nugent scores (4 to 6) |
| Bacterial vaginosis in women with HIV | Mixed | 65 | Grade D · RCT, 2010 | 65 women with HIV and abnormal vaginal flora (Nugent score 4 to 10) in Tanzania |
| Bacterial vaginosis clearance with tinidazole | Improved | 64 | Grade C · RCT, 2009 | 64 Brazilian women with bacterial vaginosis |
| Vaginal flora in healthy women | Improved | 64 | Grade C · RCT, 2003 | 64 healthy women |
| Vaginal yeast infection with fluconazole | Improved | 55 | Grade C · RCT, 2009 | 55 women with vulvovaginal candidiasis |
| CD4 count and immune markers in HIV | No effect | 55 | Grade D · RCT, 2011 | 65 Tanzanian women with HIV not on antiretroviral treatment; 10 excluded after randomisation as ineligible (55 left), 44 completed |
Every graded row
15 rowsShowing 15 of 15 outcomes. Human trials only.
CGrade CReturn to balanced vaginal flora (oral probiotic alone)Bacterial vaginosis61.5% vs 26.9% normal floraRCT
n 544 · 2013
Improved Balanced flora returned in 61.5% on probiotic vs 26.9% on placebo (p<0.001); at 12 weeks, 51.1% vs 20.8% still had normal flora (p<0.001).
- Design
- RCT, n = 544, 2013
- Population
- 544 Croatian women diagnosed with vaginal infection in a bacterial vaginosis trial (395 probiotic, 149 placebo)
- Form
- Oral L. rhamnosus GR-1 and L. reuteri RC-14 capsules (Lactogyn)
- Dose
- 1 capsule a day
- Duration
- 6 weeks, follow-up to 12 weeks
- Source
- Reference 7 · PubMed 23395559 (opens PubMed)
CGrade CRecurrent urinary tract infections vs antibiotic prophylaxisUrinary infectionsNot as good as antibioticRCT
n 252 · 2012
Mixed UTIs fell from 6.8 to 3.3 a year on lactobacilli and from 7.0 to 2.9 on the antibiotic; the 0.4 UTI difference missed the non-inferiority margin. Antibiotic resistance in E. coli rose on the antibiotic but did not rise on lactobacilli.
- Design
- RCT, n = 252, 2012
- Population
- 252 postmenopausal women with recurrent UTIs
- Form
- Oral L. rhamnosus GR-1 and L. reuteri RC-14 vs trimethoprim-sulfamethoxazole 480 mg daily
- Dose
- 1 billion CFU twice daily
- Duration
- 12 months
- Source
- Reference 9 · PubMed 22782199 (opens PubMed)
CGrade CBacterial vaginosis clearance with metronidazoleBacterial vaginosis88% vs 40% curedRCT
n 125 · 2006
Improved 88% were cured with antibiotic plus probiotic vs 40% with antibiotic plus placebo (p<0.001); high vaginal lactobacilli counts in 96% vs 53%.
- Design
- RCT, n = 125, 2006
- Population
- 125 premenopausal Nigerian women with bacterial vaginosis; 106 returned at day 30
- Form
- Oral L. rhamnosus GR-1 and L. reuteri RC-14 with oral metronidazole
- Dose
- 1 billion CFU of each strain twice daily (metronidazole 500 mg twice daily on days 1 to 7)
- Duration
- 30 days
- Source
- Reference 4 · PubMed 16697231 (opens PubMed)
CGrade CGroup B strep colonisation late in pregnancyPregnancy42.9% vs 18.0% GBS-negativeRCT
n 110 · 2016
Improved GBS changed from positive to negative in 21 women (42.9%) on probiotic vs 9 (18.0%) on placebo (p=0.007).
- Design
- RCT, n = 110, 2016
- Population
- 110 GBS-positive pregnant women at 35 to 37 weeks in Taiwan; 99 completed
- Form
- Oral L. rhamnosus GR-1 and L. reuteri RC-14
- Dose
- 2 capsules at bedtime
- Duration
- Until delivery
- Source
- Reference 11 · PubMed 27590374 (opens PubMed)
CGrade CVaginal flora after menopauseVaginal flora60% vs 16% improvedRCT
n 72 · 2008
Improved Nugent score improved by at least two grades in 21 of 35 (60%) on probiotic vs 6 of 37 (16%) on placebo (p=0.0001).
- Design
- RCT, n = 72, 2008
- Population
- 72 postmenopausal women with intermediate Nugent scores (4 to 6)
- Form
- Oral L. rhamnosus GR-1 and L. reuteri RC-14
- Dose
- 2.5 billion CFU of each strain once daily
- Duration
- 14 days
- Source
- Reference 8 · PubMed 18701205 (opens PubMed)
CGrade CVaginal flora in healthy womenVaginal flora37% vs 13% back to normal floraRCT
n 64 · 2003
Improved Microscopy showed a shift from asymptomatic bacterial vaginosis flora to normal lactobacilli flora in 37% of women on lactobacilli vs 13% on placebo (P=0.02); yeast and coliforms fell in the probiotic group; no adverse effects.
- Design
- RCT, n = 64, 2003
- Population
- 64 healthy women
- Form
- Oral capsules of L. rhamnosus GR-1 and L. fermentum (now L. reuteri) RC-14
- Dose
- Daily capsules (CFU not stated in the abstract)
- Duration
- 60 days
- Source
- Reference 3 · PubMed 12628548 (opens PubMed)
CGrade CBacterial vaginosis clearance with tinidazoleBacterial vaginosis87.5% vs 50.0% curedRCT
n 64 · 2009
Improved Cure rate 87.5% with probiotic vs 50.0% with placebo (p = 0.001); normal Nugent-score flora in 75.0% vs 34.4% (p = 0.011).
- Design
- RCT, n = 64, 2009
- Population
- 64 Brazilian women with bacterial vaginosis
- Form
- Oral L. rhamnosus GR-1 and L. reuteri RC-14 after one dose of tinidazole
- Dose
- 2 capsules every morning (tinidazole 2 g once)
- Duration
- 4 weeks
- Source
- Reference 5 · PubMed 19295645 (opens PubMed)
CGrade CVaginal yeast infection with fluconazoleYeast infection10.3% vs 38.5% still had yeastRCT
n 55 · 2009
Improved Less symptomatic discharge (10.3% vs 34.6%; P = 0.03) and less yeast on culture (10.3% vs 38.5%; P = 0.014) with probiotic than placebo.
- Design
- RCT, n = 55, 2009
- Population
- 55 women with vulvovaginal candidiasis
- Form
- Oral L. rhamnosus GR-1 and L. reuteri RC-14 after one dose of fluconazole
- Dose
- 2 capsules every morning (fluconazole 150 mg once)
- Duration
- 4 weeks
- Source
- Reference 6 · PubMed 19187507 (opens PubMed)
DGrade DHigh-risk HPV clearance and cervical smear qualityHPV58.1% vs 54.2% clearedRCT
n 121 · 2019
No effect HPV cleared in 58.1% on probiotic vs 54.2% on placebo (no significant difference). Mildly abnormal and unsatisfactory smear rates fell more with the probiotic at 6 months (p = 0.017 and 0.027).
- Design
- RCT, n = 121, 2019
- Population
- 121 Taiwanese women with genital high-risk HPV infection (62 probiotic, 59 placebo)
- Form
- Oral L. rhamnosus GR-1 and L. reuteri RC-14
- Dose
- 1 capsule a day (CFU not stated in the abstract)
- Duration
- Until a negative HPV test, checked every 3 months
- Source
- Reference 15 · PubMed 31340789 (opens PubMed)
DGrade DBacterial vaginosis in women with HIVBacterial vaginosisNo added clearance; better pHRCT
n 65 · 2010
Mixed Adding the probiotic did not raise the BV cure rate with metronidazole. In women with intermediate flora it raised the chance of a healthy vaginal pH (odds ratio 3.8; P=0.02) and tended to raise the chance of normal flora (odds ratio 2.4; P=0.1).
- Design
- RCT, n = 65, 2010
- Population
- 65 women with HIV and abnormal vaginal flora (Nugent score 4 to 10) in Tanzania
- Form
- Oral L. rhamnosus GR-1 and L. reuteri RC-14
- Dose
- Daily (CFU not stated in this abstract); women with BV also had metronidazole 400 mg twice daily for 10 days
- Duration
- 6 months
- Source
- Reference 17 · PubMed 20801446 (opens PubMed)
DGrade DCD4 count and immune markers in HIVImmune functionNo differenceRCT
n 55 · 2011
No effect CD4 count rose 46 cells/μl on probiotic vs 19 on placebo by 25 weeks (p = 0.8); no differences in immune markers, diarrhoea or adverse events.
- Design
- RCT, n = 55, 2011
- Population
- 65 Tanzanian women with HIV not on antiretroviral treatment; 10 excluded after randomisation as ineligible (55 left), 44 completed
- Form
- Oral L. rhamnosus GR-1 and L. reuteri RC-14 capsules
- Dose
- Capsules twice daily (daily CFU unclear: the abstract gives 2 billion CFU per dose in its methods but 2 billion CFU/day in its discussion)
- Duration
- 25 weeks
- Source
- Reference 16 · PubMed 21637031 (opens PubMed)
∅No effectBacterial vaginosis in early pregnancyPregnancyNo effect on BV or floraRCT
n 304 · 2020
No effect Bacterial vaginosis at 18 to 20 weeks did not differ: 15% on probiotic vs 9% on placebo (adjusted odds ratio 1.82, 95% CI 0.64 to 5.19); no change in colonisation or vaginal microbiome.
- Design
- RCT, n = 304, 2020
- Population
- 304 pregnant women recruited at 9 to 14 weeks in the UK; 238 analysed
- Form
- Oral L. rhamnosus GR-1 and L. reuteri RC-14
- Dose
- 2.5 billion CFU of each strain once daily
- Duration
- Recruitment to end of pregnancy
- Source
- Reference 10 · PubMed 30932317 (opens PubMed)
∅No effectUrinary tract infections after spinal cord injuryUrinary infectionsNo effectRCT
n 207 · 2019
No effect Risk of symptomatic UTI did not differ with RC14-GR1 (HR 0.67; 95% CI 0.39 to 1.18; P = 0.17); a post hoc analysis hinted at benefit but needs confirmation.
- Design
- RCT, n = 207, 2019
- Population
- 207 people with spinal cord injury and neurogenic bladder in Australia
- Form
- Oral L. reuteri RC-14 plus L. rhamnosus GR-1 (factorial trial with LGG plus BB-12)
- Dose
- Daily (dose not stated in the abstract)
- Duration
- 6 months
- Source
- Reference 14 · PubMed 30814670 (opens PubMed)
∅No effectGroup B strep colonisation in pregnancy (pilot)PregnancyNo differencePilot RCT
n 139 · 2021
No effect GBS colonisation at 35 to 37 weeks did not differ: 15.8% vs 21.43% (p = .48); the trial's main aim was feasibility.
- Design
- Pilot RCT, n = 139, 2021
- Population
- 139 pregnant midwifery clients in Toronto; 113 analysed
- Form
- Oral L. rhamnosus GR-1 and L. reuteri RC-14
- Dose
- 2 capsules daily from 23 to 25 weeks
- Duration
- 12 weeks
- Source
- Reference 12 · PubMed 31362572 (opens PubMed)
∅No effectBacterial vaginosis clearance with vaginal metronidazoleBacterial vaginosisNo added benefitRCT
n 126 · 2021
No effect 30-day cure 57.69% with probiotic vs 59.57% with metronidazole alone; 90-day cure 36.54% vs 48.94% (p = 0.213); probiotic strains were rarely detected in vaginal or faecal samples.
- Design
- RCT, n = 126, 2021
- Population
- 126 Chinese women with bacterial vaginosis
- Form
- Oral L. rhamnosus GR-1 and L. reuteri RC-14 added to vaginal metronidazole
- Dose
- Oral probiotic for 30 days (metronidazole suppositories for 7 days)
- Duration
- 30 days, follow-up to 90 days
- Source
- Reference 13 · PubMed 34295831 (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 results came alongside antibiotics
Pregnancy results split
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
When trials measured an effect
3 outcomes| Outcome | Measured at | Basis |
|---|---|---|
| Vaginal flora after menopause | Day 14 (end of trial) | 2.5 billion CFU of each strain daily; Nugent score improved by at least two grades in 60% vs 16%8 |
| Bacterial vaginosis clearance with metronidazole | Day 30 | 1 billion CFU of each strain twice daily; 88% vs 40% clear at day 304 |
| Balanced vaginal flora without antibiotics | Week 6, still present at week 12 | 1 capsule a day for 6 weeks; 61.5% vs 26.9% at 6 weeks and 51.1% vs 20.8% at 12 weeks7 |
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 L. rhamnosus GR-1 and L. reuteri RC-14 meets
2 cited rows 2 tested togetherMedicines 2
Supplements and foods 2
- Drug label or FDA notice
- Tested together in a graded trial
Choose a medicine or supplement above to read its cited rows here.
Also cited: 2 tested together
Antibiotics
Drug labelDrug label or FDA notice
Antibiotics, for example Metronidazole, tinidazole, trimethoprim-sulfamethoxazole: Antibiotics can kill the live bacteria; Health Canada's probiotic monograph directs taking probiotics at least 2-3 hours before or after antibiotics. In the vaginosis trials the capsules were given during or after an antibiotic course.
Source 1, Health Canada, Natural and Non-prescription Health Products Directorate (2026); Source 4, Microbes Infect (2006); Source 5, Can J Microbiol (2009)
Immunosuppressants and long-term corticosteroids
Drug labelDrug label or FDA notice
Immunosuppressants and long-term corticosteroids, for example Long-term prednisone, transplant drugs, chemotherapy: Health Canada contraindicates probiotics with an immune-compromised condition, including long-term corticosteroid treatment; NCCIH notes a higher risk of harmful infections in people with weakened immune systems.
Source 1, Health Canada, Natural and Non-prescription Health Products Directorate (2026); Source 2, National Center for Complementary and Integrative Health (NCCIH) (2019)
Bifidobacterium lactisBifidobacterium lactis page
Tested together
Urinary tract infections after spinal cord injury. Graded on the L. rhamnosus GR-1 and L. reuteri RC-14 page; tested together is not a claim that they work better together.
ProbioticsProbiotics page
Tested together
Urinary tract infections after spinal cord injury. Graded on the L. rhamnosus GR-1 and L. reuteri RC-14 page; tested together is not a claim that they work better together.
Interactions
2 agents| Agent | What the source says | Evidence |
|---|---|---|
| Medicines2 | ||
| Antibioticse.g. Metronidazole, tinidazole, trimethoprim-sulfamethoxazole | Antibiotics can kill the live bacteria; Health Canada's probiotic monograph directs taking probiotics at least 2-3 hours before or after antibiotics. In the vaginosis trials the capsules were given during or after an antibiotic course.145 | Drug label |
| Immunosuppressants and long-term corticosteroidse.g. Long-term prednisone, transplant drugs, chemotherapy | Health Canada contraindicates probiotics with an immune-compromised condition, including long-term corticosteroid treatment; NCCIH notes a higher risk of harmful infections in people with weakened immune systems.12 | Drug label |
Check with what you take
Kept on this device onlyAdd what you take. We list every interaction our evidence profiles cite between L. rhamnosus GR-1 and L. reuteri RC-14 and your picks, and between your picks.
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Add a supplement or medicine you take to check it against L. rhamnosus GR-1 and L. reuteri RC-14.
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- 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
- Pregnancy and breastfeeding
- These strains have been given in pregnancy trials from 9-14 weeks (UK, 238 analysed), 23-25 weeks (Canada, 113 analysed; no adverse effects documented) and 35-37 weeks (Taiwan) without reported safety problems (only the Canadian abstract reports on safety), but the trials were not sized to detect rare harms. There are no data on use while breastfeeding.101211
- 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, and stop if digestive upset occurs, worsens or lasts beyond 3 days.1
- Premature infants and seriously ill people
- NCCIH reports severe or fatal infections in premature infants given probiotics, and higher risk in people with severe illness.2
How to read the label
What to check on the Supplement Facts panel.
How to read the label
2 checksLook for both strain codes
Where to buy L. rhamnosus GR-1 and L. reuteri RC-14
Products from brands we partner with that contain L. rhamnosus GR-1 and L. reuteri RC-14. Check the amount per serving against the doses studied above, and the label for other ingredients.
L. rhamnosus GR-1 and L. reuteri RC-14 products from partner brands
2 products Paid links · we earn a commission- Quick pickHerbsProJarrow Formulas Fem Dophilus, 5 Billion CFU, 30 Capsules
1 capsule: 5 billion CFU total of L. rhamnosus GR-1 and L. reuteri RC-14 (guaranteed when refrigerated and within the best-used-by date)
$20.36one-timeChecked Oct 15, 2026 - Physician’s ChoicePhysician’s Choice Vaginal Probiotic (30 capsules)
1 capsule: 6 billion CFU from L. rhamnosus GR-1, L. reuteri RC-14 and L. crispatus LBV88, with 150 mg acacia fiber, 75 mg cranberry extract and 50 mg DGL; the label gives no count per strain; 30 servings
$31.95one-timeChecked Oct 20, 2026
Frequently asked questions
Short answers to common questions; the numbers link to the sources below.
Common questions
8 answersDoes it help bacterial vaginosis?
Can it replace antibiotics for recurrent UTIs?
Not on current evidence. In 252 postmenopausal women it allowed slightly more UTIs than daily trimethoprim-sulfamethoxazole (3.3 vs 2.9 a year) and missed non-inferiority, though it did not raise antibiotic resistance.9
What are the side effects of GR-1 and RC-14?
Trials reported few: no adverse effects in 64 healthy women over 60 days or in the Canadian pregnancy pilot, and no difference from placebo in adverse events over 25 weeks in women with HIV. Health Canada's probiotic monograph says to stop and ask a clinician if digestive upset such as diarrhoea worsens or lasts beyond 3 days.312161
Is it safe to take long term?
Is it useful in pregnancy?
Is it the same as other L. reuteri or L. rhamnosus products?
What are GR-1 and RC-14?
Should it be taken at the same time as antibiotics?
Sources
17 sources: trial abstracts, NIH fact sheets and reference databases. Numbers in the text link here.
Sources cited on this page
17 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
- 3Oral use of Lactobacillus rhamnosus GR-1 and L. fermentum RC-14 significantly alters vaginal flora: randomized, placebo-controlled trial in 64 healthy women.RCT FEMS Immunol Med Microbiol, 2003 · PMID 12628548
- 4Augmentation of antimicrobial metronidazole therapy of bacterial vaginosis with oral probiotic Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14: randomized, double-blind, placebo controlled trial.RCT Microbes Infect, 2006 · PMID 16697231
- 5Improved cure of bacterial vaginosis with single dose of tinidazole (2 g), Lactobacillus rhamnosus GR-1, and Lactobacillus reuteri RC-14: a randomized, double-blind, placebo-controlled trial.RCT Can J Microbiol, 2009 · PMID 19295645
- 6Improved treatment of vulvovaginal candidiasis with fluconazole plus probiotic Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14.RCT Lett Appl Microbiol, 2009 · PMID 19187507
- 7Efficacy of orally applied probiotic capsules for bacterial vaginosis and other vaginal infections: a double-blind, randomized, placebo-controlled study.RCT Eur J Obstet Gynecol Reprod Biol, 2013 · PMID 23395559
- 8Randomized, double-blind, placebo-controlled study of oral lactobacilli to improve the vaginal flora of postmenopausal women.RCT Eur J Obstet Gynecol Reprod Biol, 2008 · PMID 18701205
- 9Lactobacilli vs antibiotics to prevent urinary tract infections: a randomized, double-blind, noninferiority trial in postmenopausal women.RCT Arch Intern Med, 2012 · PMID 22782199
- 10Effects of oral probiotic supplements on vaginal microbiota during pregnancy: a randomised, double-blind, placebo-controlled trial with microbiome analysis.RCT BJOG, 2020 · PMID 30932317
- 11Oral Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 to reduce Group B Streptococcus colonization in pregnant women: A randomized controlled trial.RCT Taiwan J Obstet Gynecol, 2016 · PMID 27590374
- 12Effectiveness of oral intake of Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 on Group B Streptococcus colonization during pregnancy: a midwifery-led double-blind randomized controlled pilot trial.Pilot RCT J Matern Fetal Neonatal Med, 2021 · PMID 31362572
- 13Probiotic Lacticaseibacillus rhamnosus GR-1 and Limosilactobacillus reuteri RC-14 as an Adjunctive Treatment for Bacterial Vaginosis Do Not Increase the Cure Rate in a Chinese Cohort: A Prospective, Parallel-Group, Randomized, Controlled Study.RCT Front Cell Infect Microbiol, 2021 · PMID 34295831
- 14Probiotics [LGG-BB12 or RC14-GR1] versus placebo as prophylaxis for urinary tract infection in persons with spinal cord injury [ProSCIUTTU]: a randomised controlled trial.RCT Spinal Cord, 2019 · PMID 30814670
- 15The influence of probiotics on genital high-risk human papilloma virus clearance and quality of cervical smear: a randomized placebo-controlled trial.RCT BMC Womens Health, 2019 · PMID 31340789
- 16Effect of 25 weeks probiotic supplementation on immune function of HIV patients.RCT Gut Microbes, 2011 · PMID 21637031
- 17Lactobacillus rhamnosus GR-1 and L. reuteri RC-14 to prevent or cure bacterial vaginosis among women with HIV.RCT Int J Gynaecol Obstet, 2010 · PMID 20801446
What changed
Every dated change to this page: what changed, who made it and why.
Change log
3 entries| Date | Change | Who and why |
|---|---|---|
| evidence, interactions, who should avoid, time to effect, FAQ, questions, related | Searched PubMed for GR-1/RC-14 trials through 2026: no trial or meta-analysis newer than 2021 found. Added graded rows for HPV clearance (2019 trial, 121 women, no effect, grade D as underpowered), immune function in HIV (2011 trial, no effect, grade D) and vaginosis in women with HIV (2010 trial, mixed, grade D). Added interactions from Health Canada's probiotic monograph (take 2-3 hours apart from antibiotics; contraindicated with immune-compromised conditions including long-term corticosteroids) and a pregnancy and breastfeeding note from the pregnancy trials; LactMed and LiverTox have no probiotic entry and NCCIH has no pregnancy-specific guidance. Added time-to-effect rows, FAQ on side effects, long-term use and antibiotic timing (replacing a question the page's own who-should-be-careful section answers), page questions and the immune goal-hub link. Not added: a 7-woman urinary microbiome trial, a 29-person rheumatoid arthritis pilot and yogurt-based studies. | Writer: Kymata Health EditorialTrigger: A–Z audit against docs/supplements/AUDIT-STANDARD.md |
| where to buy | Added a 3-strain probiotic that includes GR-1 and RC-14, with its label amounts and the one-time price on the brand’s own page; it is listed as a blend because it adds a third strain and 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; none retracted) and each cited abstract read; numbers taken from the abstracts (full text used only where noted for participant counts or funding). Funding: the UK pregnancy trial was funded by Barts Charity and the spinal-cord trial by Australia's NHMRC; one author of the 2021 Chinese trial was employed by BGI-Shenzhen; the other abstracts name no funder (disclosed as not stated). RC-14 was first published as L. fermentum RC-14 (2003 trial) and later as L. reuteri. Safety only from Health Canada's Probiotics monograph (April 24, 2026) and NCCIH. Where to buy: Jarrow Fem Dophilus (label checked 2026-10-15). | Writer: Kymata Health EditorialTrigger: new page |
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