Twenty five relevant studies were identified (n=2,348): 17 randomised controlled trials (RCTs) (n=1,993), which comprised nine double-blind, one single-blind and nine placebo-controlled; and eight before-after studies with historical controls (n=355), which comprised one double-blind and placebo-controlled studies.
Of two studies each of prevention and treatment of vulvovaginal candidiasis, only one prospective cross-over trial found a significant benefit for prevention (RR 0.39, 95% CI 0.17 to 0.70).
One RCT of the five studies of prevention of urinary tract infections found a significant benefit with both lactobacilli (RR 0.42, 95% CI 0.22 to 0.67) and lactobacilli growth factor (RR 0.63).
There were nine studies of treatment of bacterial vaginosis. Of these, five RCTs and one quasi-experimental trial showed a significant reduction in infection (RR range 0.03 to 0.43).
Data for adverse events were reported for seven studies: four reported no side effects; one reported headaches and increased appetite; and two reported itching or burning sensations.
Four RCTs (of seven studies) of Lactobacillus colonisation or restoration of normal vaginal flora found a significant positive benefit.