There’s no single “best” probiotic for kids because the right choice depends on what you’re trying to address. Probiotics are strain-specific, meaning one strain might shorten a bout of diarrhea while doing nothing for colic. The strains with the strongest pediatric evidence fall into a short list, and matching the right one to your child’s situation is what actually matters.
Why the Strain Matters More Than the Brand
Walk down the supplement aisle and you’ll see dozens of kids’ probiotics with friendly cartoon labels. Most contain a grab bag of bacterial strains at varying doses. But clinical trials test specific strains for specific problems, and results from one strain don’t transfer to another, even within the same species. A product labeled “Lactobacillus” without specifying the exact strain tells you very little.
The European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) has issued position papers recommending only a handful of strains for children, and explicitly discourages using probiotics with no documented health benefits. So when choosing a product, flip to the back label and look for exact strain names like the ones below.
For Stomach Bugs and Acute Diarrhea
Lactobacillus rhamnosus GG (often listed as LGG) has the most evidence behind it for childhood diarrhea. In a randomized trial, children who received LGG during an acute bout of diarrhea recovered roughly 18 hours faster than children who didn’t. A meta-analysis pooling eight trials and nearly 1,000 children found LGG shortened diarrhea by about 1.1 days on average. ESPGHAN recommends using it alongside oral rehydration (the cornerstone treatment), not as a replacement. The studied dose for acute gastroenteritis is at least 10 billion CFU per day for five to seven days.
Saccharomyces boulardii, a beneficial yeast rather than a bacterium, also has good data for diarrhea and is the main alternative to LGG for this purpose. Because it’s a yeast, it isn’t affected by antibiotics, which gives it a distinct advantage in certain situations.
For Antibiotic Side Effects
Antibiotic-associated diarrhea is one of the most common reasons parents look into probiotics. In a double-blind trial of 246 children on antibiotics, those given Saccharomyces boulardii developed diarrhea only 8% of the time, compared to 23% in the placebo group. That’s roughly a 70% reduction in risk. When researchers looked specifically at diarrhea caused by C. difficile or otherwise unexplained by the illness being treated, the benefit was even more striking: 3.4% versus 17.3%.
LGG is also recommended for preventing antibiotic-associated diarrhea. Either strain is a reasonable choice, but S. boulardii has the practical edge of surviving alongside the antibiotic itself since antibiotics target bacteria, not yeast. If you’re giving a probiotic during an antibiotic course, spacing them a couple of hours apart is standard practice.
For Colic in Breastfed Infants
Lactobacillus reuteri DSM 17938 is the go-to strain for infant colic, particularly in breastfed babies. A meta-analysis of randomized controlled trials found it reduced daily crying time progressively: about 28 fewer minutes per day after one week, 43 fewer minutes after two weeks, and 56 fewer minutes by four weeks. That may not sound dramatic on paper, but for exhausted parents dealing with hours of inconsolable crying, an hour less per day is meaningful.
Most of the strong evidence comes from exclusively or predominantly breastfed infants, so the benefit for formula-fed babies is less clear. The studied dose is at least 100 million CFU per day, given for 21 to 30 days.
For Eczema Prevention
Lactobacillus rhamnosus HN001 (a different strain from LGG) has been studied for preventing eczema in children at high risk of allergic disease. In a large randomized trial, mothers took HN001 from 35 weeks of pregnancy through six months of breastfeeding, and infants continued supplementation until age two. This approach roughly halved the rate of eczema by age two, and the protective effect held through age four, with a 43% lower cumulative prevalence. The same trial also found reduced rates of hay fever symptoms at age four.
This is a prevention strategy started before or at birth in families with a history of allergic disease. It’s not the same as treating existing eczema with a probiotic, which has weaker evidence.
For Fewer Sick Days
Parents of daycare-age children often wonder if probiotics can cut down on the constant cycle of colds. LGG has been tested in three large trials covering over 1,300 children in daycare settings. Pooled results show it reduced the duration of respiratory infections by about 0.8 days per episode. That’s a modest effect, but across a winter season with multiple infections, it adds up. The doses used ranged from 100 million to 1 billion CFU per day.
For Newborns and Early Gut Development
A newborn’s gut microbiome is still forming, and certain strains can help tip the balance toward beneficial bacteria. Bifidobacterium infantis EVC001 has been studied in premature and full-term infants, where it rapidly becomes the dominant gut species when given during breastfeeding. It works by feeding on sugars naturally present in breast milk that the baby can’t digest on its own. In premature infants, supplementation with this strain crowded out potentially harmful bacteria like Enterobacteriaceae and Staphylococcaceae, and reduced the abundance of antibiotic resistance genes in the gut. It also produced compounds shown to reduce gut inflammation.
Dosage Basics by Age
Probiotic doses are measured in colony-forming units (CFU), and more isn’t automatically better. What matters is matching the dose to what was actually studied for that condition.
- Infants with colic (L. reuteri DSM 17938): at least 100 million (10⁸) CFU per day
- Toddlers and children preventing respiratory infections (LGG): 100 million to 1 billion (10⁸ to 10⁹) CFU per day
- Children with acute diarrhea (LGG): at least 10 billion (10¹⁰) CFU per day
- Children on antibiotics (S. boulardii or LGG): doses in trials typically ranged from 250 mg to 500 mg for S. boulardii, or 10 billion CFU for LGG
For infants, probiotics usually come as drops or powder that can be mixed into breast milk or formula. For older kids, chewable tablets and flavored powders are widely available. Check that the product guarantees its CFU count through the expiration date, not just at the time of manufacture, since live organisms die off over time.
Safety and Who Should Be Cautious
For healthy, full-term children, the probiotics listed above have strong safety profiles across hundreds of clinical trials. Side effects, when they occur, are typically mild: a bit of extra gas or a temporary change in stool consistency.
The picture changes for certain vulnerable groups. A systematic review of invasive infections linked to probiotic use found that nearly all cases involved at least one predisposing condition. Prematurity was present in 55% of cases, and the use of intravenous catheters in 51%. Children who are immunocompromised, critically ill, or have conditions that affect the integrity of their intestinal lining face a small but real risk of the probiotic organism entering the bloodstream. For these children, probiotic use should be a decision made with their medical team, not a supplement picked up at the pharmacy.
Picking a Product
Once you know which strain you need, choosing a product gets simpler. Look for the full strain designation on the label (for example, “L. rhamnosus GG,” not just “L. rhamnosus”). Confirm the CFU count matches what the research supports. Check for third-party testing or certification, since probiotics aren’t regulated as tightly as medications and products sometimes contain fewer live organisms than advertised. Store them as directed, as some strains require refrigeration while others are shelf-stable.
A probiotic that contains five or ten strains at lower doses of each isn’t necessarily better than a single well-studied strain at the right dose. In most cases, the targeted approach has stronger evidence behind it.