Probiotics for Kids: Which Strains Work, by Age and Problem

Most healthy children do not need a probiotic. Probiotics for kids help in a few specific situations: preventing diarrhea during antibiotics, possibly shortening some stomach bugs, and easing pain in some children with IBS. They do little for eczema symptoms and are not recommended for constipation^[1][2].

The benefit depends on the exact strain, not the brand or the number of bacteria on the front of the box. European pediatric gastroenterologists (ESPGHAN) only recommend strains tested in at least two randomized trials for the same problem^[1]. This guide sets out which strains have that evidence in children and toddlers, the doses studies used, safety, and how to pick a form your child will take. For babies under 12 months, see our separate guide to probiotics for infants.

Get medical help promptly if your child has diarrhea and is younger than 12 months, was born prematurely, shows signs of dehydration (no wet diaper for 3 hours or more, no tears when crying, unusual drowsiness), or cannot drink enough fluids^[3]. These need a clinician, not a probiotic.

Do kids need probiotics?

No, not as a daily routine for a healthy child. The American Academy of Pediatrics found probiotics modestly effective in two situations in healthy children: treating acute viral gastroenteritis and preventing diarrhea caused by antibiotics^[4]. Evidence for most other uses was preliminary^[4].

ESPGHAN's position paper is blunter: it says the use of probiotics with no documented health benefit should be discouraged^[1]. A probiotic is defined as live microorganisms that give a health benefit when taken in adequate amounts^[1]. A product that has not shown a benefit for your child's problem does not meet that definition for that use.

So the useful question is not "should my child take a probiotic?" but "is there a strain that has worked for this problem, in children this age?"

Which probiotic strains have evidence in children?

Only a handful of strains have enough pediatric trials for a recommendation^[1]. The table summarizes ESPGHAN's recommendations and the main Cochrane reviews.

CFU means colony-forming units, the count of live organisms. The S. boulardii used in most trials was the strain CNCM I-745^[1]. Our probiotic strain comparison explains how to read strain codes on a label.

Diarrhea from antibiotics: the strongest evidence

This is where probiotics for children work best. A Cochrane review pooled 33 trials with 6,352 children aged 0 to 18^[8].

Diarrhea developed in 8% of children given a probiotic with their prescribed antibiotic, against 19% without (risk ratio 0.45; moderate certainty)^[8]. About 9 children need a probiotic to prevent one case.

Dose mattered. At 5 billion CFU a day or more, the rate fell from 23% to 8%, and about 6 children needed treating to prevent one case^[8]. Lower doses did not show a clear effect^[8].

The two best-supported organisms are Lacticaseibacillus rhamnosus GG and the yeast Saccharomyces boulardii, started on the same day as the antibiotic^[1]. ESPGHAN suggests this mainly when a child has risk factors, such as a long course, certain antibiotic classes, a hospital stay or a previous episode^[1].

Stomach bugs: mixed results, and two large null trials

For a stomach bug (acute infectious diarrhea) that is already underway, the evidence splits. ESPGHAN's pooled analysis found L. rhamnosus GG shortened diarrhea by about one day, with the largest effect at doses above 10 billion CFU a day^[1]. The trials were of low quality and varied widely, and the effect was larger in European and Asian studies^[1].

Two large, well-run trials in North America found no benefit^[5][9].

In 971 US children aged 3 months to 4 years, L. rhamnosus GG twice daily for 5 days did not reduce moderate-to-severe illness (11.8% vs 12.6% with placebo) or diarrhea length (49.7 vs 50.9 hours)^[5].

In 886 Canadian children, a combination of L. rhamnosus R0011 and L. helveticus R0052 also made no difference^[9].

A Cochrane review of 82 trials concluded that probiotics probably make little or no difference to diarrhea lasting 48 hours or more^[10]. Partly for this reason, the American Gastroenterological Association advised against probiotics for children with acute gastroenteritis in North America^[1].

Whatever you decide about a probiotic, fluids come first: a child who cannot drink enough fluid or oral rehydration solution needs a doctor promptly^[3]. Our guide to probiotics for diarrhea covers adult and travel diarrhea as well.

Tummy pain and IBS

For children with irritable bowel syndrome, L. rhamnosus GG improved treatment success in three trials (167 children; risk ratio 1.70)^[1]. Studies used 1 to 3 billion CFU twice daily^[1]. For functional abdominal pain more broadly, Limosilactobacillus reuteri DSM 17938 reduced pain in three of five trials, but results were inconsistent^[1].

Constipation in children: what ESPGHAN advises

Many brands market probiotics for children's constipation, but ESPGHAN advises against them as a single or add-on treatment^[1]. A 2022 review of 12 studies in 965 children found mostly high-risk-of-bias trials^[1].

L. reuteri DSM 17938, the most-studied strain, did not help as an add-on in two trials^[1]. For what does help with constipation, see our guide to probiotics for constipation and talk to your pediatrician about fiber, fluids and toilet routines.

Eczema and atopic skin: little benefit for symptoms

A Cochrane review of 39 trials (2,599 participants, mostly children) found probiotics probably make little or no difference to itch and other eczema symptoms rated by parents or patients^[2]. Clinician-rated severity fell by 3.9 points on a 103-point scale, below the 8.7 points considered noticeable^[2]. The authors judged that more trials of similar strains may be futile^[2].

Can probiotics help with colds and lung infections?

For colds, this is a "maybe." A Cochrane review of 23 trials in children and adults found probiotics may reduce the number of people who catch an upper respiratory infection (risk ratio 0.76; low certainty) and the antibiotic prescriptions for them (risk ratio 0.58)^[11]. In 281 Croatian children in day care, L. rhamnosus GG in a daily fermented milk drink for 3 months cut the risk of upper respiratory infections by about a third^[6]. It did not reduce lower respiratory (chest) infections^[6].

Across 15 day-care trials, though, the only consistent effect was 0.78 fewer days of illness with LGG^[7]. Bifidobacterium animalis subsp. lactis BB-12 showed no effect on illness length or absence^[7].

Colic is a baby question

The colic evidence covers breastfed infants: L. reuteri DSM 17938 for at least 21 days, or B. lactis BB-12 for 21 to 28 days^[1]. See infant colic and our infant guide for details.

How much probiotic do studies give children?

There is no single child dose. Doses are strain-specific, and the trials above used very different amounts^[1]:

• High-dose LGG or S. boulardii during antibiotics: 5 billion CFU a day or more^[8].
• LGG for a stomach bug: 10 billion CFU a day or more for 5 to 7 days^[1]; the US trial used 10 billion CFU twice daily^[5].
• S. boulardii for a stomach bug: 250 to 750 mg a day for 5 to 7 days^[1].
• L. reuteri DSM 17938 for tummy pain: 100 to 200 million CFU a day, a far smaller number^[1].
• LGG for day-care infections: 1 billion CFU a day^[6].

A bigger CFU number is not better across strains: a reuteri product at 100 million CFU matches its trials, while an LGG product at that count would not^[1]. Match the strain and dose on the label to the trial for your child's problem, and ask your pediatrician to confirm it for your child's age and weight.

Are probiotics safe for kids?

For healthy children, probiotics are generally safe, with mild side effects. In the Cochrane review of 24 trials reporting harms, side effects occurred in 4% of children taking probiotics and 6% of controls, with no serious events linked to the probiotic^[8]. The common ones were rash, nausea, gas, bloating and constipation^[8].

The risks rise in a few groups. Serious infections from the probiotic organism itself have been reported in severely ill or immunocompromised children, especially those with a central venous catheter^[8][4]. In 2023 the FDA warned that preterm infants given probiotics can develop invasive, potentially fatal infections, after a preterm infant died of Bifidobacterium longum sepsis^[12].

Which children should not take probiotics without a doctor's advice?

Ask your child's doctor first if your child^[4][13]:

• was born prematurely or is under 12 months old;
• has a weakened immune system or a serious chronic illness;
• has a central line, port or other indwelling device;
• is seriously ill in hospital.

Product quality is the other concern. Probiotics are sold as dietary supplements, which can make structure or function claims without FDA approval^[13]. Tests have found products with misidentified strains, dead organisms, fewer bacteria than the label states and, occasionally, contaminants^[14][13].

Is yogurt as good as a probiotic supplement for kids?

Foods like yogurt and kefir are fine to offer, but they are not a substitute when you want a proven effect. A meta-analysis found only two trials of yogurt for antibiotic-associated diarrhea. Both were low quality, and the results were inconsistent^[15].

Unless a yogurt names the strain and the amount, you cannot match it to a trial. See our guide to probiotic foods for which foods actually contain live cultures.

The exception is a fermented milk that names a tested strain. The day-care trial gave LGG in 100 mL of fermented milk^[6], and in the Cochrane respiratory review children usually received probiotics in milk-based food^[11].

Which form works best for toddlers and older kids?

Pick the form that delivers the studied strain and dose, and that your child will actually take. ESPGHAN's recommendations cover probiotics in all delivery formats, so the strain and dose matter more than the format^[1].

Our article on whether probiotic gummies work explains the heat and shelf-life problem with gummies. For teens, adult products can contain the same strains at the same doses used in pediatric trials, such as LGG at 1 to 3 billion CFU twice daily for IBS pain^[1].

How to choose a probiotic for your child

1. Name the problem. Diarrhea during antibiotics, a stomach bug, IBS pain or day-care colds each have a different best-supported strain, or none.
2. Find the full strain name. Look for a code after the species, such as GG, DSM 17938 or CNCM I-745. Benefits are strain-specific^[1].
3. Check the dose at expiry. The CFU should match what trials used, and be guaranteed through the expiry date rather than "at manufacture"^[14]. Third-party testing of strain identity and count is a plus, because label errors are common^[14].
4. Time it right. For antibiotics, start on day one of the course^[1]. Our guides to when to take probiotics and how long probiotics take to work cover the rest.
5. Stop if nothing changes. Give it the length of time trials used, then reassess with your pediatrician.

For adult products and how we rank them, see our best probiotics guide.

When to see a doctor

Do not use a probiotic to put off a medical visit^[13]. Call your pediatrician promptly if your child:

• has diarrhea for more than a day, or frequent loose stools^[3];
• has any fever as a baby, or a high fever as an older child^[3];
• shows signs of dehydration: no wet diaper for 3 hours or more, no tears, a sunken soft spot, sunken eyes or cheeks, dark urine, or unusual drowsiness^[3];
• refuses to drink, or cannot keep down enough fluid or oral rehydration solution^[3];
• is under 12 months, was born prematurely, or has another medical condition and develops diarrhea^[3];
• develops new symptoms after starting a probiotic while immunocompromised or with a central line^[8].

This article is for general educational purposes and is not medical advice. Strain names and doses are those used in published studies, not dosing instructions for your child, and the evidence for most pediatric uses is of low to moderate certainty. Talk to your pediatrician before giving your child a probiotic, particularly if your child was born prematurely, is immunocompromised, has a central line, is taking prescription medication, or is managing a diagnosed condition.