Health Benefits of Probiotics for Children
Probiotics for children are one of the most confidently marketed products in the wellness aisle and one of the least settled areas of pediatric research. Those two facts do not sit comfortably together, so this article is our attempt to give you the second one straight.
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We make a liquid probiotic. You should read a probiotic company’s article about probiotics for children with a healthy amount of skepticism, and we would rather earn your trust by telling you where the evidence runs out than by hoping you don’t check. This piece is a substantial rewrite of an earlier version of ours. Several claims we used to make are gone, and we say which ones and why.
First, the important part
Nothing here is medical advice, and nothing here is a claim that Flourish treats, prevents or cures anything in a child. If your child has ongoing diarrhea, constipation, reflux, eczema, allergies, or anything else that worries you, that is a conversation with your pediatrician — not a supplement decision. Please talk to them before starting any supplement, and see the safety section below, which names specific groups of children who should not take probiotics without medical advice.
A child’s gut is genuinely under construction
This is the best-supported idea in the whole subject, and the earlier version of this article stated it without a source. It deserves one.
The TEDDY study followed 903 children from three to 46 months of age, collecting more than 12,000 stool samples. It found that the developing gut microbiome moves through “three distinct phases of microbiome progression: a developmental phase (months 3–14), a transitional phase (months 15–30), and a stable phase (months 31–46)”1.
What shaped it most? Not a supplement. “Receipt of breast milk, either exclusive or partial, was the most significant factor associated with the microbiome structure,” and “birth mode was also significantly associated with the microbiome during the developmental phase”1. Milk and how a baby was born. Those are the big levers, and neither is for sale.
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So a child’s microbial community really is different from an adult’s: it is younger, less diverse, and still assembling. The things that move it around are the ordinary ones:
- Breastfeeding — the single largest factor TEDDY identified, and stopping breast milk was associated with faster maturation of the microbiome1.
- How a baby was born — vaginal or cesarean, which shaped the community measurably through the developmental phase1.
- Food — what actually arrives on the plate as a child starts eating solids.
- Environment — where a child spends their days, and who and what they spend them around.
- Antibiotics — which, as the name suggests, do not discriminate between the bacteria making a child ill and the ones already living there2.
One small correction to our old list, in the interest of not making things up: we used to include “stress” as a factor shaping children’s microbiomes. We went looking for the pediatric evidence and could not find it. It may well be true. We just can’t point you at a study, so it’s out.
What the word “probiotic” actually means
The international consensus definition is precise and worth quoting exactly: probiotics are “live microorganisms that, when administered in adequate amounts, confer a health benefit on the host”3. Three conditions, all of them load-bearing — alive, enough of them, and a demonstrated benefit.
Species and strains are not the same thing, and we had this wrong
Our earlier article said Flourish contains “11 diverse strains.” It does not. It contains 11 species. A strain designation is genus, species, and then a specific culture-collection or commercial identifier — the difference between “a golden retriever” and “this particular golden retriever, with papers.”
This matters more than a word usually does, because almost every positive finding in the pediatric probiotic literature belongs to a named strain, not to a species. The American Gastroenterological Association puts it plainly: “Research has shown that biological functions of bacteria are specific to the strain, not the species”4. So when you read below that a particular trial found a benefit, that benefit belongs to the strain that was tested — and it does not automatically transfer to us.
The consensus panel was also careful about what can be claimed at the level of a whole class. It accepted that supporting a healthy digestive tract is a general benefit shared broadly across well-studied species. It explicitly declined to extend that to immune benefits, noting that the meaning of “supporting a healthy immune system” is “too broad to be considered a core benefit” and is “probably more strain-specific”3. It said the same about the gut–brain axis.
The honest scoreboard
Here is what the research actually found, in the four areas parents ask about most. We have put the disappointing one first, because it is the one most often reported the other way round. Everything in this section describes trials of other products and other, named strains. None of it is a claim about Flourish.
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Stomach bugs: the evidence reversed, and most articles haven’t caught up
For twenty years the standard line — ours included — was that probiotics shorten childhood diarrhea. A 2010 Cochrane review said they “appear to be safe and have clear beneficial effects in shortening the duration and reducing stool frequency in acute infectious diarrhoea”5. That was the consensus, and it is the sentence our old article was built on.
Then, in 2018, two large trials were published back to back in the New England Journal of Medicine. In the American trial, 971 children in ten pediatric emergency departments received either Lactobacillus rhamnosus GG — the single most-studied probiotic strain in children — or placebo. The conclusion: “Among preschool children with acute gastroenteritis, those who received a 5-day course of L. rhamnosus GG did not have better outcomes than those who received placebo”6. Duration of diarrhea: 49.7 hours on the probiotic, 50.9 on placebo.
The Canadian trial ran 886 children through six emergency departments on a two-strain combination and reported that it “did not prevent the development of moderate-to-severe gastroenteritis”7. Roughly 1,850 children across sixteen North American hospitals. Null on essentially every outcome.
Probiotics probably make little or no difference to the number of people who have diarrhoea lasting 48 hours or longer.
Cochrane revisited the question in 2020 with 82 studies and 12,127 participants. It found publication bias in the literature, and when it restricted the analysis to trials at low risk of bias, the effect disappeared — including for L. rhamnosus GG and S. boulardii specifically. The conclusion above is theirs, verbatim8.
The American Gastroenterological Association now recommends against it: “In children with acute infectious gastroenteritis, we suggest against the use of probiotics”9. Their technical review is blunter still — the panel “did not identify a single trial conducted in the United States or Canada that reported a beneficial effect for a probiotic in the context of acute gastroenteritis in children”10.
What we used to say, and why it’s gone
Our earlier article said “studies have shown that probiotics can reduce the duration and severity of acute diarrhea in children, particularly when caused by infections.” The citation behind it was a meta-analysis from 2002 whose literature search stopped in the year 2000. It has been superseded by roughly 1,850 children’s worth of randomized evidence pointing the other way. The sentence is deleted.
Antibiotic-associated diarrhea: the strongest finding in the field
This one goes the other way, and it is worth separating carefully from the last one — our old article ran them together in a single sentence, and they now have opposite standing.
A 2019 Cochrane review pooled 33 studies and 6,352 children taking antibiotics. Diarrhea occurred in 8% of the probiotic group versus 19% of controls — a number needed to treat of 9, at moderate certainty11. The effect was dose-dependent: at five billion CFU a day or more, the number needed to treat fell to 6.
That is a real result. Two honest caveats travel with it. The certainty is moderate, not high. And the reviewers were specific about whose benefit it is: the evidence concerns Lactobacillus rhamnosus and Saccharomyces boulardii, and they wrote that it is “premature to draw firm conclusions about the efficacy and safety of ‘other’ probiotic agents as an adjunct to antibiotics in children”11. Flourish is an “other” agent. This is not our finding to borrow.
Colds: better evidence than you would guess
A 2022 Cochrane review of 6,950 people found probiotics “likely reduce the number of participants who used prescribed antibiotics for acute upper respiratory tract infections” — and that one is moderate certainty12. The effect on catching a cold at all was weaker and low certainty. Most of the trials used one or two named strains.
Curiously, the evidence for gastrointestinal infections in otherwise healthy children is worse. The best daycare trial of the best-studied strain found a clear reduction in respiratory infections and no significant reduction in gastrointestinal ones13. Our old article claimed the opposite of what the data show, which is a good illustration of how easily this material gets repeated in the wrong direction.
Allergies: one signal, and a lot of noise
We have removed everything our earlier article said about eczema. The current Cochrane review of probiotics for treating eczema concluded that “use of probiotics for the treatment of eczema is currently not evidence-based”14, and the 2025 Cochrane review on prevention found that when the analysis was limited to trials at low risk of bias there was little or no difference in eczema by age two15. The 2023 American allergy guideline makes 25 recommendations on managing atopic dermatitis and does not mention probiotics once16. There is no honest version of that paragraph, so it is gone.
Hay fever is the one place with a genuine positive signal, and it comes with a large asterisk. A 2026 systematic review of 14 trials in 1,739 children with allergic rhinitis found reduced nasal and eye symptom scores and improved quality of life — but with statistical heterogeneity between studies of 91–96%, which is high enough that the pooled numbers should be read as a direction rather than a measurement. The authors’ own words: these findings “should be interpreted with caution due to substantial heterogeneity across studies,” and probiotics “may have a potential role as an adjunctive therapy” while “further high-quality, standardized trials are needed”17. A separate review of 28 studies reached the same place: “clinicians should be cautious when recommending probiotics in treating allergic rhinitis”18.
Read that one carefully
Those trials studied specific named strains, in children who had already been diagnosed with allergic rhinitis, under medical supervision. Flourish has not been studied for this, we are not suggesting it does this, and nobody should use a supplement in place of treatment their doctor has recommended. We have included the finding because it exists and because leaving it out would be its own kind of dishonesty — not because it says anything about our product.
Two sections we deleted outright
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Our earlier article had a section on mental health and one on cognitive development. Both are gone, and we think you should know what was behind them.
Mood and anxiety. A 2025 systematic review searched 1,561 studies and found ten randomized trials, totaling 408 children, on microbiota-based interventions for depression or anxiety. Every one of those children had a diagnosed condition — autism, irritable bowel syndrome, Prader–Willi syndrome, anorexia nervosa, or literacy difficulties. Seven of the ten trials found no significant effect19. There are no trials in generally healthy children. Not weak ones. None.
Attention, memory and learning. We claimed all three. The best available meta-analysis across the human lifespan found cognitive benefits mainly in older adults; in infants and children, the only domain that reached significance was executive function, with a small effect whose confidence interval barely cleared zero20. Attention was not shown in children. Memory was not shown in children. Learning was not measured. We wrote a sentence the literature does not support.
We had also attributed the supposed cognitive benefit to “reduction of systemic inflammation.” We could find no evidence that a probiotic reduces systemic inflammation in children, or that any such reduction improves how children think. That sentence is gone too.
The gut–brain axis is a real and fascinating field. It is also one the international consensus panel specifically declined to include among the benefits that can be attributed to probiotics as a class3. We will write about it again when there is something to report.
Is it safe? Mostly yes — with named exceptions
Our old article had no safety section at all. For an article aimed at parents, that was the worst omission in it.
In generally healthy children, the trial record is reassuring. A large federally commissioned evidence review covering 622 studies found no statistically significant increase in adverse events with short-term probiotic use21. Cochrane reviews across several pediatric indications report the same.
But that same review was candid about the limits of its own evidence: adverse events were “poorly documented,” controlled trials “did not monitor routinely” for bloodstream infections, and “long-term effects are largely unknown”21. Case reports of bloodstream infection with the administered organism do exist — in one, genetic fingerprinting confirmed that the bacterium in a child’s blood was the same one in the tablets22. And the review’s summary of who is at risk is consistent across every source we read: “participants with compromised health are most likely to experience adverse events associated with probiotics”21.
Ask a doctor first if your child is in any of these groups
Premature or hospitalised infants. Children who are immunocompromised. Children who are chronically debilitated or seriously ill. Children with a central venous catheter, or with short-gut syndrome or another condition affecting the gut barrier. These groups are named consistently by the American Academy of Pediatrics23, by Cochrane11, and by FDA.
In September 2023 FDA warned that probiotic products used in hospitals had “contributed to invasive disease, including one infant death in 2023,” and stated that “the FDA has not approved any probiotic product for use as a drug or biological product in infants of any age”24. Flourish Junior is not for premature or hospitalised infants, and we would rather say that here than leave you to find it out somewhere else.
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Where Flourish fits
Flourish Junior is a fermented living liquid containing 11 species of bacteria. It pours. You can measure a dose to a child’s size, and there is no capsule to swallow — which matters if you have ever tried to get a four-year-old to swallow a capsule. Everyone in the house can use the same bottle.
Those are facts about the format. They are not claims about outcomes, and we are not going to dress them up as claims about outcomes.
The comparison we are not making
Our earlier article said Flourish is “never freeze-dried into capsules” and that its composition “helps Flourish make its way safely through the stomach.” We went looking for the evidence and there isn’t any. No published or registered trial has ever compared a liquid probiotic against a freeze-dried one on any clinical outcome, in any population, at any age.
The one human study we found comparing delivery formats gave the same organism as a yogurt smoothie or as a capsule and found no significant difference in gut microbiota composition, transit time, or short-chain fatty acids25. We have retracted a very similar comparison in another article, and we are retracting this one for the same reason: we cannot support it.
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One genuinely useful thing we did learn while checking, and it slightly complicates our own convenience pitch. In a laboratory model of the human upper digestive tract, probiotic survival through the stomach depended most on what it was taken with. Survival was best with a meal or thirty minutes before one, and “survival in milk with 1% milk fat and oatmeal-milk gruel were significantly better than apple juice or spring water”26.
That was a model, not a clinical trial, and it studied a capsule product rather than ours. But if you are going to stir a dose into something for your child, milk with breakfast is a better bet than juice or water on an empty stomach. We would rather tell you that than let you imagine the bottle does all the work.
What we would actually say to a parent
A child’s gut microbiome is real, it is developing, and the things that shape it most are ordinary and mostly free: food, breastfeeding where it is possible, time outdoors, and not taking antibiotics that aren’t needed.
A probiotic is not a substitute for any of that, and on the evidence available today it is not a treatment for anything in a healthy child. Some parents like adding live cultures to the family’s routine, the way they like adding yogurt or kefir, and that is a perfectly good reason to do it. It is the reason we would give.
If your child is unwell, please call your pediatrician rather than a supplement company. That includes us.
About this article
Written by: Kelsy Armstrong, Entegro Health | Originally published: August 2024
Important information
This article is for general education and isn’t a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or another qualified health provider with any questions about your child’s health, and never disregard or delay professional advice because of something you have read here.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
Sources
- Stewart, C. J., Ajami, N. J., O’Brien, J. L., Hutchinson, D. S., Smith, D. P., Wong, M. C., et al. (2018). Temporal development of the gut microbiome in early childhood from the TEDDY study. Nature, 562(7728), 583–588 — 903 children; three phases of microbiome progression; breast milk the most significant factor. Source
- Guo, Q., Goldenberg, J. Z., Humphrey, C., El Dib, R., & Johnston, B. C. (2019). Probiotics for the prevention of pediatric antibiotic-associated diarrhea. Cochrane Database of Systematic Reviews, 4(4), CD004827 — antibiotics alter the microbial balance. Source
- Hill, C., Guarner, F., Reid, G., Gibson, G. R., Merenstein, D. J., Pot, B., et al. (2014). Expert consensus document: The International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotic. Nature Reviews Gastroenterology & Hepatology, 11(8), 506–514 — “live microorganisms that, when administered in adequate amounts, confer a health benefit on the host”; immune and gut–brain benefits excluded from class-level claims. Source
- American Gastroenterological Association. AGA Issue Brief for Media: Probiotics (updated 29 May 2020) — “Research has shown that biological functions of bacteria are specific to the strain, not the species.” Source
- Allen, S. J., Martinez, E. G., Gregorio, G. V., & Dans, L. F. (2010). Probiotics for treating acute infectious diarrhoea. Cochrane Database of Systematic Reviews, (11), CD003048 — the superseded 2010 conclusion, cited here only to document the reversal. Source
- Schnadower, D., Tarr, P. I., Casper, T. C., Gorelick, M. H., Dean, J. M., O’Connell, K. J., et al. (2018). Lactobacillus rhamnosus GG versus placebo for acute gastroenteritis in children. New England Journal of Medicine, 379(21), 2002–2014 — N=971; relative risk 0.96 (95% CI 0.68–1.35), P=0.83. Source
- Freedman, S. B., Williamson-Urquhart, S., Farion, K. J., Gouin, S., Willan, A. R., Poonai, N., et al. (2018). Multicenter trial of a combination probiotic for children with gastroenteritis. New England Journal of Medicine, 379(21), 2015–2026 — N=886; odds ratio 1.06 (95% CI 0.77–1.46), P=0.72. Source
- Collinson, S., Deans, A., Padua-Zamora, A., Gregorio, G. V., Li, C., Dans, L. F., & Allen, S. J. (2020). Probiotics for treating acute infectious diarrhoea. Cochrane Database of Systematic Reviews, 12(12), CD003048 — 82 studies, 12,127 participants; publication bias demonstrated; “probiotics probably make little or no difference.” Source
- Su, G. L., Ko, C. W., Bercik, P., Falck-Ytter, Y., Sultan, S., Weizman, A. V., & Morgan, R. L. (2020). AGA clinical practice guidelines on the role of probiotics in the management of gastrointestinal disorders. Gastroenterology, 159(2), 697–705 — “In children with acute infectious gastroenteritis, we suggest against the use of probiotics” (conditional recommendation, moderate quality of evidence). Source
- Preidis, G. A., Weizman, A. V., Kashyap, P. C., & Morgan, R. L. (2020). AGA technical review on the role of probiotics in the management of gastrointestinal disorders. Gastroenterology, 159(2), 708–738.e4 — “did not identify a single trial conducted in the United States or Canada that reported a beneficial effect.” Source
- Guo, Q., Goldenberg, J. Z., Humphrey, C., El Dib, R., & Johnston, B. C. (2019). Probiotics for the prevention of pediatric antibiotic-associated diarrhea. Cochrane Database of Systematic Reviews, 4(4), CD004827 — 33 studies, 6,352 children; 8% vs 19%, NNTB 9, moderate certainty; dose-dependent; “premature to draw firm conclusions about… ‘other’ probiotic agents.” Source
- Zhao, Y., Dong, B. R., & Hao, Q. (2022). Probiotics for preventing acute upper respiratory tract infections. Cochrane Database of Systematic Reviews, 8(8), CD006895 — 6,950 participants; prescribed-antibiotic use RR 0.58 (95% CI 0.42–0.81), moderate certainty. Source
- Hojsak, I., Snovak, N., Abdović, S., Szajewska, H., Mišak, Z., & Kolaček, S. (2010). Lactobacillus GG in the prevention of gastrointestinal and respiratory tract infections in children who attend day care centers. Clinical Nutrition, 29(3), 312–316 — N=281; respiratory infections RR 0.66; gastrointestinal infections RR 0.63 (95% CI 0.38–1.06), not significant. Source
- Makrgeorgou, A., Leonardi-Bee, J., Bath-Hextall, F. J., Murrell, D. F., Tang, M. L., Roberts, A., & Boyle, R. J. (2018). Probiotics for treating eczema. Cochrane Database of Systematic Reviews, 11(11), CD006135 — 39 RCTs, 2,599 participants; “use of probiotics for the treatment of eczema is currently not evidence-based.” Source
- Wang, H. Z., Hayles, E. H., Fiander, M., Sinn, J. K., & Osborn, D. A. (2025). Probiotics in infants for prevention of allergic disease. Cochrane Database of Systematic Reviews, 6(6), CD006475 — eczema RR 0.86 (95% CI 0.69–1.07) in low-risk-of-bias trials; “insufficient evidence to make conclusions.” Source
- Chu, D. K., Schneider, L., Asiniwasis, R. N., Boguniewicz, M., De Benedetto, A., Ellison, K., et al.; AAAAI/ACAAI Joint Task Force on Practice Parameters (2024). Atopic dermatitis (eczema) guidelines: 2023 AAAAI/ACAAI GRADE- and Institute of Medicine-based recommendations. Annals of Allergy, Asthma & Immunology, 132(3), 274–312 — 25 recommendations; probiotics not addressed. Source
- Bakhshi, A., Poursadegh, F., Salari, M., et al. (2026). Effect of probiotics on allergic rhinitis in children: a systematic review and meta-analysis. European Journal of Pediatrics, 185(6), 447 — 14 RCTs, 1,739 children; nasal symptoms SMD −1.40 with I²=91.3%; “interpreted with caution due to substantial heterogeneity.” Source
- Luo, C., Peng, S., Li, M., Ao, X., & Liu, Z. (2022). The efficacy and safety of probiotics for allergic rhinitis: a systematic review and meta-analysis. Frontiers in Immunology, 13, 848279 — 28 studies; “clinicians should be cautious when recommending probiotics in treating allergic rhinitis”; no significant change in IgE. Source
- Hu, J., Zhang, Y., Liu, C., Gkaravella, A., & Yu, J. (2025). Effects of microbiota-based interventions on depression and anxiety in children and adolescents: a systematic review. Journal of Pediatric Gastroenterology and Nutrition, 81(2), 404–416 — 10 RCTs, 408 participants, all with a diagnosed condition; 7 of 10 reported no significant effect. Source
- Effects of probiotics on cognitive function across the human lifespan: a meta-analysis (2025). European Journal of Clinical Nutrition — 21 RCTs; benefits principally in older adults; in infants and children only executive function reached significance (SMD 0.30, 95% CI 0.04–0.56). Source
- Hempel, S., Newberry, S., Ruelaz, A., Wang, Z., Miles, J. N., Suttorp, M. J., et al. (2011). Safety of probiotics used to reduce risk and prevent or treat disease. Evidence Report/Technology Assessment No. 200. Agency for Healthcare Research and Quality — 622 studies; no significant increase in adverse events (RR 1.00) but “long-term effects are largely unknown” and “participants with compromised health are most likely to experience adverse events.” Source
- De Groote, M. A., Frank, D. N., Dowell, E., Glode, M. P., & Pace, N. R. (2005). Lactobacillus rhamnosus GG bacteremia associated with probiotic use in a child with short gut syndrome. Pediatric Infectious Disease Journal, 24(3), 278–280 — molecular typing confirmed the blood isolate matched the administered product. Source
- Thomas, D. W., & Greer, F. R.; American Academy of Pediatrics Committee on Nutrition and Section on Gastroenterology, Hepatology, and Nutrition (2010). Probiotics and prebiotics in pediatrics. Pediatrics, 126(6), 1217–1231 — names safety concerns in children who are immunocompromised, chronically debilitated, or seriously ill with indwelling medical devices. Source
- U.S. Food and Drug Administration (2023). FDA raises concerns about probiotic products sold for use in hospitalized preterm infants. Press announcement — probiotic products “contributed to invasive disease, including one infant death in 2023”; “the FDA has not approved any probiotic product for use as a drug or biological product in infants of any age.” Source
- Ba, Z., Lee, Y., Meng, H., Kris-Etherton, P. M., Rogers, C. J., Riedl, K. M., et al. (2021). Matrix effects on the delivery efficacy of Bifidobacterium animalis subsp. lactis BB-12 on fecal microbiota, gut transit time, and short-chain fatty acids in healthy young adults. mSphere, 6(4), e00084-21 — randomized crossover, 36 adults; yogurt smoothie versus capsule showed no significant difference in microbiota, transit time or SCFAs. Source
- Tompkins, T. A., Mainville, I., & Arcand, Y. (2011). The impact of meals on a probiotic during transit through a model of the human upper gastrointestinal tract. Beneficial Microbes, 2(4), 295–303 — “survival in milk with 1% milk fat and oatmeal-milk gruel were significantly better than apple juice or spring water.” Source
