Lactobacillus reuteri

Limosilactobacillus reuteri · L. reuteri

Snapshot

Indications	Contraindications
Infant colic¹ Pediatric acute gastroenteritis^{2, 3} Helicobacter pylori eradication adjunct⁴ Functional abdominal pain⁵ Antibiotic-associated diarrhea⁶ Total cholesterol⁷ Chronic periodontitis with scaling^8–10 Social behavior in autism¹¹	Immune-compromised condition¹² Milk allergy¹³

Lactobacillus reuteri (Limosilactobacillus reuteri) is a gut commensal probiotic with immune-regulating effects¹⁴. It secretes reuterin, which inhibits pathogen growth¹⁵. Supplementation supports gut microbial balance, and the best-studied uses follow: colic in breastfed infants, acute diarrhea in children, and functional abdominal pain in children. Adults take it as an adjunct to Helicobacter pylori eradication therapy and for total cholesterol. In depression, a meta-analysis found benefit with mixed-strain products but not with L. reuteri alone¹⁶.

For colic, an individual participant data meta-analysis found benefit in breastfed but not formula-fed infants¹. In acute gastroenteritis, a meta-analysis found shorter diarrhea, with small effect sizes². A meta-analysis of randomized trials found higher Helicobacter pylori eradication rates and fewer adverse events with L. reuteri adjuncts⁴. A 2026 systematic review in children with autism spectrum disorder found longer-term L. reuteri supplementation was consistently associated with better social behavior, though high-quality evidence is limited¹¹. Products listing Lactobacillus reuteri number 2792, mostly capsules with some tablets and softgels; see Form comparison.

Health Canada lists immune-compromised conditions, including long-term corticosteroid treatment, as a contraindication¹². Per Health Canada labels, fever, vomiting, bloody diarrhoea, or severe abdominal pain carry a request for practitioner advice before use¹².

Last updated October 16, 2026. Read how we make monographs.

In the full monograph

78 sources, 66 studies

When to useThe situations practitioners use it for, each with the reason and the study behind it.
SafetyWho should avoid it, who needs extra care, and the side effects reported in studies.
InteractionsThe medicines and supplements it interacts with, the effect of each, and what labeling says to watch.
Protocol notesThe doses used in studies, how and when they were taken, and how the forms on the market compare.
How it worksWhat it is and how it works in the body, in plain terms.
Published studiesThe studies behind each use, popular claims checked against them, and trials still under way.
Word of mouthWhat patients and practitioners report online, kept separate from the clinical evidence.
Clinical perspectiveA closing read of where the evidence is solid, where it is thin, and what has not been studied.

Snapshot

In the full monograph

Sources