Research
Lactobacillus rhamnosus GR-1 for Bladder Health: Evidence, Interactions and Cautions
Lactobacillus rhamnosus GR-1 is an ingredient used in bladder supplements marketed to women. Below is what it has actually been studied for, how strong that evidence is, the drug interactions and cautions on record, and the primary source our grade rests on — all drawn from the HerWellReport ingredient dataset.
Also sold as: L. rhamnosus GR-1; GR-1; usually sold paired with L. reuteri RC-14
What the evidence says about Lactobacillus rhamnosus GR-1
The 2015 Cochrane review of probiotics for preventing UTI pooled 9 studies and 735 participants and found no clear benefit over placebo (RR 0.82, 95% CI 0.60 to 1.12), rating all outcomes low quality because of small samples and poor reporting. The GR-1/RC-14 study it included gave postmenopausal women oral capsules of at least 10 to the 9 CFU twice daily for 12 months against trimethoprim-sulfamethoxazole, and the review's probiotic-versus-antibiotic comparison found no significant difference (RR 1.12, 95% CI 0.95 to 1.33, one study, 223 women). With no placebo arm in that comparison you cannot tell whether both worked or neither did. NCCIH's own summary of the same review states it did not find evidence of a beneficial effect.
The grade "limited" means: limited — One or two small human trials, or trials for a closely related outcome. Grades are explained in full on our methodology page.
Read the primary source this grade rests on (opens in a new tab).
Lactobacillus rhamnosus GR-1 drug interactions
No documented drug interactions in the sources we checked. That is not the same as proof of safety alongside your medication — it usually means the question has not been studied. Ask a pharmacist before combining it with prescription drugs.
Who should be careful with Lactobacillus rhamnosus GR-1
- Avoid if you are severely ill or immunocompromised: NCCIH reports infections and other serious harms are more likely in those groups
- some probiotic products have been found to contain organisms other than those on the label
Read more on HerWellReport
- Do Probiotics Actually Help Bladder Health?
- 65 Ingredients, None Proven: What Is Actually Inside the Supplements Sold to Women (2026)
- FemiCore vs AZO Bladder Control: Ingredients, Price and Guarantee Compared
- Is It Normal to Pee Every Hour? What Counts as Normal Urinary Frequency
- MenoRescue vs Provitalize: Ingredients, Price and Guarantee Compared
This entry is generated from row "Lactobacillus rhamnosus GR-1" of the HerWellReport ingredient dataset (v2.1, updated 2026-09-23). The dataset is free to reuse under CC BY 4.0 — how to cite it. Ingredient evidence is not evidence for any finished product, and nothing here is medical advice.