Which probiotic strain is best for baby colic?

Lactobacillus reuteri DSM 17938 has the most evidence for reducing colic symptoms in breastfed infants. Multiple randomized controlled trials show it can reduce daily crying time. Evidence for formula-fed infants is weaker and inconsistent.

Can probiotics help with baby eczema?

Some studies suggest certain Lactobacillus strains may reduce eczema risk when given during pregnancy and early infancy, particularly in high-risk families. However, a 2018 Cochrane review found the evidence insufficient to recommend routine use for eczema prevention.

Are probiotics safe for newborns?

Probiotics appear safe for healthy, term infants based on available evidence. However, they should be avoided in premature infants, immunocompromised babies, or those with central venous catheters without medical guidance, as rare cases of probiotic-related sepsis have been reported in these populations.

How long should I try probiotics before deciding they don't work?

Most studies showing benefit used a 2-3 week trial period. If you don't see improvement in your baby's symptoms after 3 weeks of consistent use, the probiotics likely aren't helping your specific situation.

GUIDE

Probiotics for Babies vs. No Probiotics

The evidence is mixed. Certain strains (especially L. reuteri) show promise for colic in breastfed babies, but probiotics aren't a universal solution. For healthy, term infants without specific symptoms, routine probiotic supplementation isn't necessary.

Probiotics are a billion-dollar industry with a lot of marketing and less clinical clarity than you'd expect.

Track symptoms with Tinylog

Log symptoms before and after starting probiotics

“There's no data to show that these extra ingredients will make your baby healthier.”

Dr. Matthew Badgett, MD, Pediatrician, Cleveland Clinic

Cutting Through the Marketing

The infant probiotic market has exploded in recent years, with dozens of products promising better digestion, less fussiness, stronger immunity, and even better sleep. Walk down the baby aisle and you'll find probiotics in drops, powders, formula, and even baby food. The marketing suggests every baby needs them. The science tells a different story.

The strongest evidence exists for one specific strain — Lactobacillus reuteri DSM 17938 — and one specific condition — colic in breastfed infants. A meta-analysis by Sung et al. (2018) in the Journal of Pediatrics analyzed data from four RCTs and found that L. reuteri reduced daily crying time by approximately 50 minutes compared to placebo in breastfed infants. That's meaningful. But the same analysis found the benefit was not significant in formula-fed infants, and the studies had moderate risk of bias.

For everything else — eczema prevention, constipation, general "gut health," immune support — the evidence ranges from weak to nonexistent. A 2019 review by the European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) concluded that while certain strains show promise for specific conditions, there is insufficient evidence to recommend routine probiotic supplementation for healthy infants. The AAP has not issued a recommendation for or against infant probiotics, noting the evidence is still evolving.

Probiotics vs. No Probiotics by Condition

Condition	With Probiotics	Without Probiotics
For colic (breastfed)	L. reuteri DSM 17938 reduced crying time by ~50 minutes/day in multiple RCTs. Most consistent evidence.	Colic typically resolves by 3-4 months regardless. Soothing techniques and time are the main 'treatment.'
For colic (formula-fed)	Evidence is weak and inconsistent. Some trials show no benefit in formula-fed infants specifically.	Formula changes (hydrolyzed, low-lactose) may be more effective than probiotics for formula-fed colicky babies.
For eczema prevention	Some positive signals, especially in high-risk families. Evidence is inconsistent across studies.	Breastfeeding, moisturizing, and avoiding known triggers remain the first-line approach.
For constipation	Limited evidence. A few small studies suggest possible benefit. Not well-established.	Dietary changes, adequate fluid intake, and age-appropriate interventions are standard treatment.
Cost	$15-40/month depending on brand and formulation.	$0. No additional cost.
Safety	Generally safe for healthy term infants. Avoid in preemies or immunocompromised infants without medical guidance.	No risk. Healthy infant gut microbiome develops naturally through breastmilk, food exposure, and environmental contact.

For colic (breastfed)

With ProbioticsL. reuteri DSM 17938 reduced crying time by ~50 minutes/day in multiple RCTs. Most consistent evidence.

Without ProbioticsColic typically resolves by 3-4 months regardless. Soothing techniques and time are the main 'treatment.'

For colic (formula-fed)

With ProbioticsEvidence is weak and inconsistent. Some trials show no benefit in formula-fed infants specifically.

Without ProbioticsFormula changes (hydrolyzed, low-lactose) may be more effective than probiotics for formula-fed colicky babies.

For eczema prevention

With ProbioticsSome positive signals, especially in high-risk families. Evidence is inconsistent across studies.

Without ProbioticsBreastfeeding, moisturizing, and avoiding known triggers remain the first-line approach.

For constipation

With ProbioticsLimited evidence. A few small studies suggest possible benefit. Not well-established.

Without ProbioticsDietary changes, adequate fluid intake, and age-appropriate interventions are standard treatment.

Cost

With Probiotics$15-40/month depending on brand and formulation.

Without Probiotics$0. No additional cost.

Safety

With ProbioticsGenerally safe for healthy term infants. Avoid in preemies or immunocompromised infants without medical guidance.

Without ProbioticsNo risk. Healthy infant gut microbiome develops naturally through breastmilk, food exposure, and environmental contact.

Evidence quality varies significantly. Colic in breastfed infants has the strongest data.

Probiotic Advantages

L. reuteri has consistent evidence for reducing colic symptoms in breastfed infants
Generally well-tolerated with an excellent safety profile in healthy term babies
May provide modest benefit for certain digestive symptoms
Easy to administer — most come as drops mixed into milk or placed on the nipple
Some evidence for reducing antibiotic-associated diarrhea if baby needs antibiotics

Benefits are strain-specific. A product with L. reuteri DSM 17938 is not interchangeable with a generic blend.

Probiotic Challenges

Most probiotic products have never been tested in clinical trials for infants
Strain-specific — benefits of one strain don't transfer to another, but marketing rarely makes this clear
Not FDA-regulated for efficacy — quality and viable colony counts vary between brands
Expensive for something with modest evidence, and costs add up over months
Can create false reassurance — parents may delay seeking medical advice for symptoms that need evaluation

The supplement industry's lack of regulation means you're often paying for marketing, not proven benefit.

No-Probiotic Advantages

Saves money — no ongoing supplement cost
Healthy infant gut microbiome develops naturally through breastmilk, birth method, and environment
Avoids introducing unregulated supplements to a developing system
Breastmilk contains its own prebiotics (HMOs) that selectively feed beneficial gut bacteria
No risk of rare adverse events associated with live bacterial supplementation

A healthy term baby's gut microbiome develops remarkably well on its own.

No-Probiotic Challenges

If baby has colic, you miss a potentially helpful intervention (for breastfed infants specifically)
May feel like 'doing nothing' when your baby is uncomfortable, which is hard for parents
C-section babies and formula-fed babies may have less diverse initial gut microbiomes
If baby needs antibiotics, gut microbiome disruption may be more significant without probiotic support

For colicky breastfed babies, skipping probiotics means missing one of the few evidence-based interventions.

Tinylog symptom tracker showing daily fussiness and digestive logs

Log symptoms before and after to know if it's working

Tinylog lets you track fussiness, gas, spit-up, and stool patterns daily. Start logging before you begin probiotics, then compare — data beats guessing when you're sleep-deprived.

When Probiotics Might Make Sense

Based on the current evidence, probiotics are worth discussing with your pediatrician if your breastfed baby has colic (excessive crying without another medical explanation), your baby is taking antibiotics and you want to reduce the risk of antibiotic-associated diarrhea, or your family has a strong history of atopic conditions (eczema, allergies, asthma) and you want to explore prevention options during pregnancy and early infancy.

In these situations, the potential benefit is supported by at least some clinical evidence, and the risk for healthy term infants is very low. The key is choosing the right strain for the right indication — not grabbing a generic product off the shelf.

For healthy babies without specific symptoms, routine probiotic supplementation is spending money on a product with no proven benefit. Breastmilk already contains human milk oligosaccharides (HMOs) — prebiotics that selectively feed beneficial gut bacteria. Nature's probiotic delivery system is hard to beat. If you're weighing whether to breastfeed or use formula, our breastfeeding vs. formula feeding guide covers the gut-health angle as well.

How to Evaluate a Probiotic Product

If you decide to try probiotics, look for products that list the specific strain (genus, species, and strain designation — e.g., L. reuteri DSM 17938, not just "Lactobacillus"), guarantee colony-forming units (CFUs) through the expiration date rather than just "at time of manufacture," have been tested in published clinical trials for the condition you're targeting, and follow good manufacturing practices.

Be skeptical of products making broad claims like "supports overall gut health" or "boosts immunity" without referencing specific studies. These claims are legal because probiotics are classified as supplements, not drugs, and don't require evidence to support marketing language. For a similar breakdown of another common OTC remedy, see our gripe water vs. gas drops comparison.

Tips That Apply Either Way

Strain matters more than brand

If you decide to try probiotics, look for the specific strain studied in clinical trials — L. reuteri DSM 17938 for colic (sold as BioGaia Protectis). Generic 'baby probiotics' with untested strains are a gamble.

Give it 2-3 weeks

Don't expect overnight results. Clinical trials showing benefit used 2-3 week treatment periods. Track symptoms daily so you can objectively assess whether things are improving, staying the same, or getting worse.

Talk to your pediatrician first

This is especially important for premature babies, babies with immune conditions, or babies on medications. Your pediatrician can recommend specific strains and dosing appropriate for your baby's situation.

Related Guides

Best Baby Formulas 2026 — Formula options including those with added probiotics
Baby Constipation — When to worry and what helps
Food Allergy Signs in Babies — Symptoms to watch for

Sources

Sung, V., et al. (2018). Lactobacillus reuteri to Treat Infant Colic: A Meta-analysis. Pediatrics, 141(1), e20171811.
Szajewska, H., et al. (2019). Probiotics for the Management of Pediatric Gastrointestinal Disorders: Position Paper of the ESPGHAN Working Group. Journal of Pediatric Gastroenterology and Nutrition, 69(1), 170-182.
Cuello-Garcia, C. A., et al. (2015). Probiotics for the prevention of allergy: A systematic review and meta-analysis of randomized controlled trials. Journal of Allergy and Clinical Immunology, 136(4), 952-961.
Osborn, D. A., & Sinn, J. K. H. (2013). Probiotics in infants for prevention of allergic disease and food hypersensitivity. Cochrane Database of Systematic Reviews, (3).

This guide is for informational purposes only and is not a substitute for professional medical advice. Consult your pediatrician for guidance specific to your baby.

Get this comparison in your inbox.

We'll send you the evidence summary so you can make an informed choice.

Log symptoms before and after to see if probiotics are making a real difference.

Download Tinylog to track digestive symptoms, fussiness, and changes over time.