Objective: To determine whether administration of Lactobacillus reuteri (L. reuteri) DSM 17938 is beneficial in breastfed infants with infantile colic.

Study design: Eighty infants aged <5 months with infantile colic (defined as crying episodes lasting 3 or more hours per day and occurring at least 3 days per week within 7 days prior to enrollment), who were exclusively or predominantly (>50%) breastfed were randomly assigned to receive L. reuteri DSM 17938 (10⁸ colony-forming units) (n = 40) or an identically appearing and tasting placebo (n = 40), both orally, in 5 drops, 1 time daily, for 21 days. The primary outcome measures were the treatment success, defined as the percentage of children achieving a reduction in the daily average crying time ≥ 50%, and the duration of crying (minutes per day) at 7, 14, 21, and 28 days after randomization.

Results: The rate of responders to treatment was significantly higher in the probiotic group compared with the placebo group at day 7 (P = .026), at day 14 (relative risk (RR) 4.3, 95% CI 2.3-8.7), at day 21 (RR 2.7, 95% CI 1.85-4.1), and at day 28 (RR 2.5, 95% CI 1.8-3.75). In addition, throughout the study period, the median crying time was significantly reduced in the probiotic group compared with the control group.

Conclusion: Exclusively or predominantly breastfed infants with infantile colic benefit from the administration of L. reuteri DSM 17938 compared with placebo.