Effect of Probiotic Use Containing Lactobacillus rhamnosus GG and Bifidobacterium animalis subsp. lactis on Clinical Outcomes in Children Aged 2–12 Years Receiving Antibiotic Therapy: A Multicenter Cohort Study

Objective: This study aimed to evaluate the association between probiotic supplementation containing Lactobacillus rhamnosus GG and Bifidobacterium animalis subsp. lactis and antibiotic-associated diarrhea, gastrointestinal tolerability, healthcare utilization, and social outcomes in children aged 2–12 years receiving antibiotic therapy, using real-world clinical data.Materials and Methods: This multicenter cohort study included children aged 2–12 years who were prescribed antibiotic therapy for an infectious diagnosis in pediatric outpatient clinics and/or departments of pediatrics across 15 centers between January 1, 2026, and June 1, 2026. Patients were categorized according to probiotic use during antibiotic therapy into the probiotic group, receiving supplementation containing L. rhamnosus GG and B. animalis subsp. lactis in addition to antibiotics (Group 1, n=120), and the control group, receiving antibiotics alone (Group 2, n=120). The primary outcome was antibiotic-associated diarrhea, defined as three or more loose or watery stools within 24 hours without an alternative clinical explanation. Secondary outcomes included gastrointestinal symptoms, repeat healthcare visits, antibiotic modification or discontinuation, school/daycare absenteeism, and parental workday loss. Continuous variables were compared using the Mann–Whitney U test, whereas categorical variables were analyzed using the chi-square test or Fisher’s exact test, as appropriate. Multivariable logistic regression analysis was performed to identify independent factors associated with antibiotic-associated diarrhea.Results: A total of 240 children were included, with 120 patients in each group. Baseline characteristics, including age, sex, antibiotic indication, antibiotic class, and duration of antibiotic therapy, were comparable between the groups. The incidence of antibiotic-associated diarrhea was significantly lower in the probiotic group than in the control group (16.7% vs. 32.5%; p=0.007). Probiotic supplementation was associated with a 49% relative reduction in the risk of antibiotic-associated diarrhea (RR=0.51; 95% CI: 0.32–0.83). The probiotic group also had significantly shorter diarrhea duration, lower maximum daily stool frequency, and lower rates of abdominal pain, flatulence, bloating, nausea/vomiting, repeat healthcare visits, hospitalization, antibiotic modification/discontinuation, need for additional treatment, school/daycare absenteeism, and parental workday loss.Conclusion: In children aged 2–12 years receiving antibiotic therapy, supplementation with Lactobacillus rhamnosus GG and Bifidobacterium animalis subsp. lactis was associated with a lower incidence of antibiotic-associated diarrhea and a reduced clinical and social burden, supporting its potential role as a practical adjunctive strategy to improve gastrointestinal tolerability during antibiotic treatment.