Over the 6-month study period, 51% of women taking 2-g D-mannose powder daily had a further episode of a suspected UTI for which they contacted ambulatory care compared with 55.7% of women taking ...

One systematic review of seven studies could not determine if taking D-mannose long-term compared with no treatment, other supplements, or antibiotics reduced the number of repeated UTIs.

Overall, 303 women were randomly assigned to D-mannose (50.7%) and 295 to placebo (49.3%). Participants received either 2 g/d of D-mannose powder or the same amount of placebo powder.