Objective: The goal was to test the hypothesis that oral administration of Lactobacillus reuteri in a prospective randomized study would improve symptoms of infantile colic.

Methods: Ninety breastfed colicky infants were assigned randomly to receive either the probiotic L. reuteri (10⁸) live bacteria per day) or simethicone (60 mg/day) each day for 28 days. The mothers avoided cow’s milk in their diet. Parents monitored daily crying times and adverse effects by using a questionnaire.

Results: Eighty-three infants completed the trial: 41 in the probiotic group and 42 in the simethicone group. The infants were similar regarding gestational age, birth weight, gender, and crying time at baseline. Daily median crying times in the probiotic and simethicone groups were 159 minutes/day and 177 minutes/day, respectively, on the seventh day and 51 minutes/day and 145 minutes/day on the 28th day. On day 28, 39 patients (95%) were responders in the probiotic group and 3 patients (7%) were responders in the simethicone group. No adverse effects were reported.

Conclusions: In our cohort, L. reuteri improved colicky symptoms in breastfed infants within 1 week of treatment, compared with simethicone, which suggests that probiotics may have a role in the treatment of infantile colic.