Probiotics for children: What does the research show?

Many parents consider lactic acid bacteria, also called probiotics, when their child starts nursery, needs penicillin or has tummy ache. The shelves are full of drops and chewable tablets, and several of them also contain vitamin D.

Short answer: The research in children is mixed, and it depends on the exact strain. A large Danish trial found no fewer sick days in nursery. During antibiotics the evidence is better, but only for a few strains at high doses. And for tummy ache and constipation in older children, the professional societies recommend other things first.

Nursery and day care: A Danish trial found no difference

Children who start day care often fall ill. So it is natural to ask whether probiotics can help.

The best answer for Danish parents comes from the ProbiComp trial at the University of Copenhagen. 290 healthy children aged 8 to 14 months got either placebo or two common strains, a Bifidobacterium animalis subsp. lactis and a Lactobacillus rhamnosus, with 1 billion bacteria of each daily for 6 months from the start of day care [1]. The result:

• On average the children were at home 11 days in the period, and there was no difference between the groups.
• Nor was there any difference in doctor visits, antibiotic courses, diarrhoea, fever or parents' absence from work.

Other trials have found an effect:

• In Croatia, 281 children in day care had L. rhamnosus GG (LGG) in a milk drink for 3 months. They had fewer colds and other upper respiratory infections than with placebo, but not significantly fewer stomach infections [2].
• In Mexico, 336 children aged 6 to 36 months had L. reuteri DSM 17938 for 3 months. They had fewer and shorter episodes of diarrhoea and respiratory infection [3].
• A trial in Indonesia with 494 children aged 1 to 6 years and the same strain found no clear difference in diarrhoea by the WHO definition and no difference in respiratory infections [4].

A pooled analysis from 2026 of 9 trials in children under 2 found that probiotics did not lower the risk of colds and other upper respiratory infections. The authors write that the evidence does not support routine use at that age [5].

During antibiotics: Best documented, but for few strains

Antibiotics often cause diarrhoea, and here the evidence is best. A Cochrane review of 33 trials with over 6,000 children found diarrhoea in 8% with probiotics against 19% without. For every 9 children who got probiotics, one child avoided diarrhoea [6].

But the difference was largest with high doses, at least 5 billion bacteria a day. The European Society for Paediatric Gastroenterology (ESPGHAN) recommends only two specific types, if probiotics are to be used: L. rhamnosus GG and the yeast Saccharomyces boulardii. Other strains and blends lack evidence, the society writes [7].

Note that none of the children's products we review below contains LGG or S. boulardii. Read more about probiotics during a course of penicillin and about what LGG has been studied for.

Stomach infection and colic

We have written about these two separately, so here are only the main points:

• Acute stomach infection: The largest trial, with 971 children under 4, found no difference in how long the diarrhoea lasted with LGG [8]. Fluids are still what matters most.
• Colic in babies: L. reuteri DSM 17938 reduced crying in breastfed babies with colic in a pooled analysis of four trials. In formula-fed babies the effect was not significant [9].

Read the full review in the article on probiotics for babies and colic.

Tummy ache and constipation in older children

Many school children have recurring tummy ache with no disease behind it. In their 2025 guideline, the European and North American paediatric gastroenterology societies recommend hypnotherapy and cognitive behavioural therapy most strongly. Probiotics may be suggested, but with weak evidence, and the only strain named is LGG, only for irritable bowel syndrome (IBS) [10].

The guideline makes no recommendation for L. reuteri DSM 17938, even though it is the strain with the most trials. A pooled analysis from 2026 of five trials on tummy ache and five on constipation found no clear effect of the strain [11].

For constipation, a review of trials in children found no evidence for probiotics [12]. The Danish Paediatric Society writes in its 2025 guideline that treatment with prebiotics and probiotics is not recommended [13]. Talk to the doctor about treatment if the constipation does not go away.

Read more about functional abdominal pain.

Eczema and allergy: No prevention

A Cochrane review from 2025 of 24 trials with over 7,000 mother and child pairs found that probiotics given to babies do not prevent asthma, hay fever or food allergy. For eczema there was a small difference, but it disappeared when only the best-run trials were included. The authors conclude that the evidence is not good enough to recommend it [14].

Vitamin D drops with probiotics

Several products combine probiotics with vitamin D. That is practical, but it requires knowing the recommendation.

The Danish Health Authority recommends that all children get 10 µg of vitamin D a day all year from 2 weeks to 4 years [15]. In addition:

• A baby who drinks at least 800 ml a day of infant formula with at least 1.3 µg of vitamin D per 100 ml should not have a vitamin D supplement.
• From 1½ years, a children's multivitamin can replace the vitamin D drops. The child should then not also have vitamin D drops.
• From 4 years, 5 to 10 µg a day is recommended from October to April.

A product with both vitamin D and probiotics should therefore replace the ordinary vitamin D drops, not be given on top. The vitamin D is what the Danish Health Authority recommends. The probiotics are an extra, and whether they make a difference depends on the strain.

Who should not have probiotics?

In healthy children side effects are rare. The American Academy of Pediatrics does, however, advise particular caution in children with a weakened immune system, serious chronic illness, or a catheter or other medical device in the body [16]. Cases have been described where the very bacterium from a probiotic product caused blood poisoning [17].

For premature babies, the neonatal unit decides. Read more in the article on who should not take probiotics.

How to read the pack

The most important thing is the strain code, such as "DSM 17938" or "GG". Without it you cannot look up the research, and two strains of the same species can behave differently. Read more about CFU and strain codes.

Here are the four children's products from Med24 we have reviewed, set against the research above:

Product	Form and age	Vitamin D	Has the strain been studied in trials in children?
Semper D-vitamindråber	Drops, from birth	10 µg	Yes, L. reuteri DSM 17938 at the same dose as in the colic trials
Semper Dråber	Drops, from birth	No	Yes, same strain and dose
Lactocare Baby	Drops, 2 weeks to 4 years	10 µg	We have found no trials with the strains
Lactocare Kids + D	Chewable tablets, from 3 years	10 µg	We have found no trials with the strains

Remember that a strain that has been studied is not the same as a strain that works for everything. The strain in the Semper drops has evidence for colic in breastfed babies, but the trials in older children with tummy ache found no clear effect [11]. None of the products contains LGG or S. boulardii, which are the ones recommended during antibiotics.

The bottom line

• A Danish trial with 290 children found no fewer sick days in nursery with probiotics.
• During antibiotics, high doses of LGG or S. boulardii have the best evidence.
• For tummy ache and constipation in older children, the professional societies recommend other things first.
• Probiotics do not prevent allergy.
• Vitamin D drops with probiotics should replace ordinary vitamin D drops, not be given on top.
• Look for the strain code, and talk to the health visitor or doctor if your child is ill.

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Sources

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2. Hojsak I et al. Lactobacillus GG in the prevention of gastrointestinal and respiratory tract infections in children who attend day care centers. Clin Nutr. 2010. PMID 19896252
3. Gutierrez-Castrellon P et al. Diarrhea in preschool children and Lactobacillus reuteri: a randomized controlled trial. Pediatrics. 2014. PMID 24639271
4. Agustina R et al. Randomized trial of probiotics and calcium on diarrhea and respiratory tract infections in Indonesian children. Pediatrics. 2012. PMID 22492764
5. Carnazzo SM et al. Strain-Specific Effects of Early-Life Probiotic Supplementation on Respiratory Infections in Infants: A Systematic Review and Meta-Analysis. Nutrients. 2026. PMID 42451071
6. Guo Q et al. Probiotics for the prevention of pediatric antibiotic-associated diarrhea. Cochrane Database Syst Rev. 2019. PMID 31039287
7. Szajewska H et al. Probiotics for the Prevention of Antibiotic-Associated Diarrhea in Children. J Pediatr Gastroenterol Nutr. 2016. PMID 26756877
8. Schnadower D et al. Lactobacillus rhamnosus GG versus Placebo for Acute Gastroenteritis in Children. N Engl J Med. 2018. PMID 30462938
9. Sung V et al. Lactobacillus reuteri to Treat Infant Colic: A Meta-analysis. Pediatrics. 2018. PMID 29279326
10. Groen J et al. ESPGHAN/NASPGHAN guidelines for treatment of irritable bowel syndrome and functional abdominal pain-not otherwise specified in children aged 4-18 years. J Pediatr Gastroenterol Nutr. 2025. PMID 40444524
11. Quatrale G et al. Limosilactobacillus reuteri DSM 17938 in pediatric functional abdominal pain disorders and functional constipation. J Pediatr Gastroenterol Nutr. 2026. PMID 42811720
12. Tabbers MM et al. Nonpharmacologic treatments for childhood constipation: systematic review. Pediatrics. 2011. PMID 21949142
13. Dansk Pædiatrisk Selskab. Obstipation og fækalinkontinens hos børn og unge. Guideline. 2025. paediatri.dk
14. Wang HZ et al. Probiotics in infants for prevention of allergic disease. Cochrane Database Syst Rev. 2025. PMID 40511642
15. Sundhedsstyrelsen. Anbefalinger om tilskud med D-vitamin og calcium. sst.dk
16. Thomas DW, Greer FR. Probiotics and prebiotics in pediatrics. Pediatrics. 2010. PMID 21115585
17. Land MH et al. Lactobacillus sepsis associated with probiotic therapy. Pediatrics. 2005. PMID 15629999

This article is general information and not medical advice.