Systematic review: Limosilactobacillus reuteri DSM 17938 for preventing antibiotic‐associated diarrhoea in children

Abstract Objectives Probiotic effects are strain‐specific; each strain needs to be assessed individually. In this review, we evaluated the effectiveness of Limosilactobacillus reuteri DSM 17938 in preventing antibiotic‐associated diarrhoea (AAD) in children receiving systemic antibiotics. Methods We searched the Cochrane Library, MEDLINE, EMBASE and trial registries (January 2016–July 2025) for randomized controlled trials (RCTs) comparing L. reuteri DSM 17938 with placebo, no treatment, or other probiotics in children. Risk of bias was assessed with Risk of Bias 2 (ROB‐2), and certainty of evidence with Grading of Recommendations, Assessment, Development and Evaluation (GRADE). Results Three RCTs (1070 randomized, 998 analysed) were included. No significant effect was observed with ≤14‐day administration (two RCTs, n = 901; risk ratio [RR] 0.85, 95% confidence interval [CI]: 0.26–2.77; low certainty evidence), with interpretation limited by heterogeneity ( I 2 = 91%) and analytical differences. A regimen of up to 21 days reduced AAD risk (two RCTs, n = 751; RR: 0.50, 95% CI: 0.33–0.75; moderate certainty evidence). A post hoc analysis of trials with follow‐up up to 56 days showed no significant effect (three RCTs, n = 998; RR: 0.85, 95% CI: 0.29–2.46; I 2 = 83%). A subgroup analysis limited to children receiving amoxicillin‐clavulanate showed benefit (two RCTs, n = 690; RR: 0.49, 95% CI: 0.32–0.76; I 2 = 0%). Conclusions L. reuteri DSM 17938 may reduce the risk of AAD in children when administered for up to 21 days or in those receiving amoxicillin‐clavulanate. No benefit was found with shorter administration or extended follow‐up. Further high‐quality trials are needed before routine use can be recommended.