Probiotics for Colic

"Probiotic" has become a word that sounds evidence-based by default, the way "natural" or "clinically tested" do. It isn't automatically. The actual colic research is specific to one strain, and most products on a pharmacy shelf labeled "probiotic" aren't that strain.

The strain with the strongest evidence base is Lactobacillus reuteri DSM 17938. Savino et al.'s 2010 randomized controlled trial in Pediatrics found a 74% reduction in daily crying by day 21 in breastfed infants using this exact strain. A 2017 network meta-analysis (Gutiérrez-Castrellón et al., Medicine), covering 32 randomized trials and 2,242 infants across multiple interventions, ranked this strain ahead of the other approaches studied. Two additional independent systematic reviews, Ellwood et al. 2020 (BMJ Open) and Hjern et al. 2020 (Acta Paediatrica), reached compatible conclusions.

32 randomized trials. 2,242 infants. One strain ranked ahead of every other intervention studied.Gutiérrez-Castrellón et al., Medicine, 2017

That level of replication across independent research groups is unusual in this space, and it's specific to this strain and dose, not to probiotics as a category. A generic probiotic product, or a different strain entirely, hasn't been tested the same way and shouldn't be assumed to carry the same evidence. This strain is sold under the brand name BioGaia Protectis, typically dosed at 5 drops daily added to breast milk or formula.

Two caveats worth stating plainly, not burying. First, the Savino trial specifically enrolled breastfed infants; see Breastfeeding and Colic for that detail and what the broader systematic reviews say for formula-fed and mixed-fed babies. Second, gut microbiome imbalance is one of three possible root-cause systems, not a universal explanation. If nervous system dysregulation or feeding mechanics is the more likely driver for your baby, a gut-focused intervention, however well-evidenced for the right baby, isn't addressing the actual mechanism at play. The root-cause guide covers all three, and the assessment sorts out which is more likely primary for yours.