Lactobacillus reuteri
Useful mainly for breastfed infants with colic (strain DSM 17938).
Quick decision guide
May help most
breastfed infants with colic (strain DSM 17938)
Common dosing range
strain-dependent; ~100 million–1 billion CFU/day for infant colic
When to expect effects
1–3 weeks (colic)
Watch out for
avoid live probiotics in severely immunocompromised or critically ill patients
What is it
Lactobacillus reuteri (now reclassified as Limosilactobacillus reuteri) is a probiotic bacterium found naturally in the human gut and breast milk. It has been studied for infant colic, oral health, gut health, and immune support, with different strains having different documented effects.
Is it worth it for you?
Use this as a quick fit check, not a diagnosis.
Worth considering if…
Probably skip if…
Evidence at a glance
| Goal | Effect | Best fit | Time |
|---|---|---|---|
infant colic Good Evidence | Reduced daily crying time | breastfed term infants with colic (strain DSM 17938) | 1–3 weeks |
helicobacter pylori eradication (adjunct) Limited Evidence | Better tolerability; modest effect on eradication | adults undergoing H. pylori eradication therapy | Course of therapy |
gingivitis and oral health Limited Evidence | Small reductions in gingival inflammation | adults with gingivitis (oral strains, e.g. ATCC PTA 5289 lozenges) | Weeks |
ldl cholesterol Limited Evidence | Small LDL reduction | adults with mildly elevated cholesterol (strain NCIMB 30242) | Weeks |
infant colic
- Effect
- Reduced daily crying time
- Best fit
- breastfed term infants with colic (strain DSM 17938)
- Time
- 1–3 weeks
helicobacter pylori eradication (adjunct)
- Effect
- Better tolerability; modest effect on eradication
- Best fit
- adults undergoing H. pylori eradication therapy
- Time
- Course of therapy
gingivitis and oral health
- Effect
- Small reductions in gingival inflammation
- Best fit
- adults with gingivitis (oral strains, e.g. ATCC PTA 5289 lozenges)
- Time
- Weeks
ldl cholesterol
- Effect
- Small LDL reduction
- Best fit
- adults with mildly elevated cholesterol (strain NCIMB 30242)
- Time
- Weeks
Evidence for 4 uses
AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.
infant colic
Disease adjunctRandomized trials and pooled analyses show L. reuteri DSM 17938 reduces crying time in breastfed infants with colic. The benefit is most consistent in breastfed infants and less clear in formula-fed ones. This effect is strain-specific and should not be generalized to other L. reuteri products.
Bottom line: Strain DSM 17938 reduces crying in breastfed colicky infants.
helicobacter pylori eradication (adjunct)
Disease adjunctAdded to standard antibiotic regimens, L. reuteri may improve treatment tolerability and modestly support H. pylori eradication in some trials. Results are mixed and it is an adjunct to, not a replacement for, antibiotics. L. reuteri produces reuterin, an antimicrobial compound.
Bottom line: A reasonable adjunct that may aid tolerability of H. pylori therapy, with modest evidence.
gingivitis and oral health
Supplement benefitSmall trials of L. reuteri lozenges report reductions in gingival inflammation and plaque indices, as an adjunct to oral hygiene. Studies are small and strain-specific, using oral-contact formulations. Confidence is low.
Bottom line: Oral-strain lozenges may modestly reduce gingivitis as a hygiene adjunct.
ldl cholesterol
Biomarker supportL. reuteri NCIMB 30242 has lowered LDL and total cholesterol modestly in a small number of randomized trials, attributed to bile salt hydrolase activity. This is a lipid biomarker effect from limited, strain-specific data, not a demonstrated reduction in cardiovascular events. Confidence is low.
Bottom line: A specific strain modestly lowers LDL biomarkers, but clinical outcomes are unproven.
How it works
How to take it
What to track
3 commercial forms
Compare the main delivery options and what they’re best suited for.
L. reuteri DSM 17938
Most studied strain for infant colic and digestive symptoms. Available as oil-based drops for infants.
Acid-stable, well-studied in infants
L. reuteri NCIMB 30242
Studied for cardiovascular markers including LDL cholesterol reduction in adults.
Bile-salt hydrolase activity
L. reuteri ATCC PTA 5289
Used in lozenges and chewing tablets for gum and oral health.
Designed for oral cavity adhesion
Safety
Know the common side effects, key cautions, and who should avoid it.
Common side effects
Serious risks
bacteremia in immunocompromised individuals (rare)
Who should avoid it
- severely immunocompromised people
- those with central venous catheters
- critically ill or preterm infants without specialist supervision
Pregnancy & breastfeeding
Pregnant and breastfeeding women appear to tolerate L. reuteri well.
Interactions
kill probiotic organisms; separate dosing by at least 2 hours
may increase small risk of bacterial translocation
Food sources
| Food | Amount | %DV |
|---|---|---|
| Some fermented dairy products | Variable; not all yogurts or kefirs contain L. reuteri | — |
| Sourdough breads (some) | Variable; mostly killed during baking | — |
| Human breast milk | Natural source for infants | — |
Some fermented dairy products
- Amount
- Variable; not all yogurts or kefirs contain L. reuteri
- %DV
- —
Sourdough breads (some)
- Amount
- Variable; mostly killed during baking
- %DV
- —
Human breast milk
- Amount
- Natural source for infants
- %DV
- —
Choosing a product
What to look for on the label — and what to be skeptical of.
Look for…
Be skeptical of…
Frequently asked questions
Is L. reuteri safe for infants?⌄
L. reuteri DSM 17938 has been studied in healthy term infants and is generally considered safe. Discuss with your pediatrician before giving any supplement to an infant, especially preterm or medically fragile babies.
Does L. reuteri actually help with colic?⌄
Multiple trials show reduced crying time in breastfed colicky infants. Effects are smaller and less consistent in formula-fed babies. It is one of the better-studied options, but results vary by individual.
Can L. reuteri lower cholesterol?⌄
The NCIMB 30242 strain has shown modest LDL cholesterol reductions in trials. The effect is small compared to statins but may complement dietary changes for mild dyslipidemia.
How is L. reuteri different from L. rhamnosus?⌄
They are different species with different metabolic profiles and documented uses. L. reuteri produces reuterin, an antimicrobial; L. rhamnosus has different surface proteins and stronger evidence for acute diarrhea.
Should I refrigerate L. reuteri drops?⌄
Check label directions. Some L. reuteri products are shelf-stable; others require refrigeration to maintain potency.
References by claim
helicobacter pylori eradication (adjunct)
Track Lactobacillus reuteri with Pilora
Set up dose reminders, check interactions, and join the community in the Pilora iPhone app.
Coming to App StoreDisclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you’re pregnant, breastfeeding, on medications, or managing a chronic condition.