Research
D-mannose for Bladder Health: Evidence, Interactions and Cautions
D-mannose 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: Mannose; a simple sugar related to glucose
What the evidence says about D-mannose
The 2022 Cochrane review pooled seven randomised trials in 719 people and found the studies too small, too varied and too biased to meta-analyse, concluding there is little to no evidence either way. The largest trial since, MERIT, randomised 598 UK women in primary care to 2 g daily or placebo and found no benefit: 51.0% versus 55.7% contacted care for a suspected UTI (risk difference -5%, 95% CI -13% to 3%), and its authors said d-mannose should not be recommended for prophylaxis. NICE still lists it as something some non-pregnant women may wish to try as self-care, on the strength of a single earlier trial. No study has looked at urinary leaks.
The grade "very limited for UTI prevention; none for leaks" means: very limited — Mostly animal, laboratory or anecdotal evidence, with at most a single weak human study. none — No human trial evidence we could find for this use. Grades are explained in full on our methodology page.
Read the primary source this grade rests on (opens in a new tab).
D-mannose 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 D-mannose
- Not in pregnancy
- Counts towards your daily sugar intake
- Can cause diarrhoea or vaginal burning
Read more on HerWellReport
- Best Bladder Control Supplements for Women (2026): What’s Actually in Them
- Cystex Review (2026): The Cranberry Dose It Won’t Disclose
- Do Bladder Control Supplements Actually Work? What the Evidence Says for Women Over 40
- Recurrent UTIs in Women: Why They Keep Coming Back
This entry is generated from row "D-mannose" 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.