Can a probiotic stop UTIs from coming back?
NCT ID NCT03366077
First seen Jun 24, 2026 · Last updated Jun 26, 2026 · Updated 1 time
Summary
This study tested whether taking a probiotic called Lactobacillus reuteri could reduce the number of repeat urinary tract infections (UTIs) in adult women who had recently finished antibiotic treatment for a UTI. 140 women with a history of recurrent UTIs took either the probiotic or a placebo daily for six months. Researchers tracked how many confirmed UTIs occurred during that time to see if the probiotic helped prevent them.
What this could mean
Our plain-language read of the trial. This is informational only, not medical advice or a prediction.
- Active substance
- probiotic (Lactobacillus reuteri)
- What this could lead to
- If it works, this could offer a natural way to help prevent repeat UTIs without relying on antibiotics.
- What could go wrong
- This is a small, completed study with 140 women, and probiotics may not work for everyone. Results may not apply to all women or different probiotic strains.
This is an AI summary of the original study and may miss details. Read our disclaimer.
Study facts
What this study's own registry entry says, in plain language.
- Phase
-
Not a phased trial
Phase numbers describe drug development. The registry uses this when they do not apply, as it does for trials of devices, procedures or behaviour changes, and for observational studies.
- Participants
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140 people
The number who actually took part.
- Started
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Dec 2017
- Finished
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Jul 2019
- Lead sponsor
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A company
The lead sponsor is a pharmaceutical, biotech, or medical-device company.
Who can take part
This study's own entry requirements. Only the study team can say for certain whether you qualify.
- Ages
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18 to 50 years
- Sex
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Female participants only
- Healthy volunteers
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Accepted
You do not need to have the condition being studied to take part.
Show the full entry requirements Hide the full entry requirements
Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.
Inclusion Criteria: 1. Willing and able to give informed consent for participation in the study. 2. Woman aged 18-50 years old at screening. 3. BMI ≥18 at screening. 4. Currently on antibiotic treatment for UTI, at the time of screening. Antibiotic treatment must stop within three days prior to first IP dose. 5. Recurrent UTI defined as at least two UTIs during the last six months or at least three UTIs during the last 12 months, according to information given by the subject. 6. Able and willing to comply with the restrictions defined for the the study period (see Section 10.6). 7. Access to Bank ID and ability to use the e-health platform (i.e. Internet access). 8. Ability to understand and comply with the requirements of the study, as judged by the Investigator. Exclusion Criteria: 1. Postmenopausal (defined as 12 months of amenorrhoea). 2. Pregnant or breastfeeding. 3. Planning to become pregnant during the study. 4. Irregular menstruations combined with perimenopausal symptoms. 5. Known hypersensitivity or allergy to any of the components of the test product, or to the comparator (placebo). 6. Use of spermicide contraceptives including spermicidal condom within three days prior to first IP dose. 7. History of complicated cystitis, urgency incontinence, recent pyelonephritis, urological and/or gynaecologist abnormalities, immunocompromised, as judged by the Investigator. 8. Unstable bowel disorder such as diarrhoea, Crohn's disease, ulcerative colitis. \-
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Conditions
The condition(s) this trial relates to.
As listed by the trial registrant
The condition terms exactly as the trial's registrant entered them.
Contacts and locations
Locations
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Clinical Trial Consultants AB
Uppsala, 752 37, Sweden