Cranberry juice prevents recurrences of urinary tract infections (UTIs) in adult women, but evidence for its efficacy in children is lacking. This RCT aimed to evaluate whether cranberry juice could prevent UTI recurrences in children.

The study was conducted in 7 hospitals in Finland in 263 children treated for UTI who were randomised to receive either cranberry juice (n = 129) or placebo (n = 134) for 6 months. The children were monitored for 1 year, and their recurrent UTIs were recorded. The primary end point was the occurrence of the first UTI episode during the 12-month follow-up. Secondary end points were the UTI incidence density and antimicrobial use.

The final analyses involved 255 children (8 omitted due to protocol violations) noted the following:

• 20 children (16%) in the cranberry group and 28 (22%) in the placebo group had at least 1 recurrent UTI (difference, −6%; 95% CI, −16 to 4%; p = 0.21).

• There were no differences in timing between these first recurrences (p= 0.32).

• Episodes of UTI totaled 27 and 47 in the cranberry and placebo groups, respectively, and the UTI incidence density per person-year at risk was 0.16 episodes lower in the cranberry group (95% CI, −.31 to -.01; p = 0.035).

• The children in the cranberry group had significantly fewer days on antimicrobials (−6 days per patient-year; 95% CI, −7 to −5; p < 0.001).

The researchers conclude from these findings that cranberry juice did not significantly reduce the number of children who experienced a recurrence of UTI. Secondary outcome measures indicated a decrease in the actual number of recurrences and related antimicrobial use.