Across 3 studies, 2 reported beneficial effects on reduced crying duration, with 1 large effect (systematic review of 2,242 infants with colic, WMD -51.3 h [CI95% -72.2 to -30.5 h], p=0.0001) and 1 small significant effect (review of breastfed infants). The remaining study (RCT, n=89 neonates on antibiotics) found no statistically significant benefit. The median study duration was 42 days. The predominant effect direction is beneficial, but effect sizes are mixed (small to large). Most evidence pertains to infants with colic.
Caveats: Evidence base is small (only 3 studies) — conclusions should be considered preliminary. The single largest study (systematic review, n=2,242) reports a large beneficial effect, but it is a meta-analysis that may include overlapping data. One recent RCT (2024) in antibiotic-exposed neonates found no significant benefit, suggesting effectiveness may depend on the specific population. One study did not report a sample size.
L reuteri DSM 17938 [WMD -51.3 h (CI95% -72.2 to -30.5 h), P .0001]
the probiotic group presented a longer sleep duration and shorter crying time than the control group, but the difference was not statistically significant.
for breastfed infants, Lactobacillus reuteri DSM 17938 is associated with fewer crying minutes