Probiotic Drops for Newborns: Do They Really Help With Colic?

Colic is one of the most exhausting and emotionally draining experiences of early parenthood. A baby who cries inconsolably for three or more hours a day, three or more days a week, for three or more weeks — the classic clinical definition — puts enormous strain on parents who have tried feeding adjustments, positions, white noise, carrying, and every other settling technique available, only to find nothing consistently works. In that context, the promise of a simple daily supplement that could reduce or eliminate the crying feels genuinely transformative. Probiotic drops for newborns colic have become one of the most discussed interventions in this space, and the conversation around them has intensified as the research has grown.

The evidence is more interesting than a simple yes or no. Probiotic drops for newborns with colic sit in a space where the research is promising but not yet definitive, where the answer depends significantly on which probiotic strain is used, and where the mechanism of action is becoming clearer without being fully understood. This guide covers what the current science actually says, which strains have the most evidence behind them, what parents can realistically expect, and how probiotics fit into a broader approach to managing a colicky newborn.

What Colic Actually Is and Why It Remains Poorly Understood

Before evaluating whether probiotics help, understanding what colic actually is — and what it isn't — provides essential context. Despite decades of research, colic remains a diagnosis of exclusion: it describes a pattern of excessive, inconsolable crying in an otherwise healthy infant for which no specific medical cause has been identified. It affects an estimated ten to twenty-five percent of newborns depending on the population studied, typically begins in the second or third week of life, peaks around six weeks, and resolves spontaneously for most babies by three to four months.

The spontaneous resolution is the most important feature of colic from a research standpoint, because it means any intervention introduced during the colic period will appear to work simply because the baby is approaching the natural resolution point regardless of what is done. This is why controlled studies with comparison groups are essential for evaluating any colic intervention — and why anecdotal parent reports, however compelling and sincerely offered, cannot substitute for properly designed research.

The cause of colic is genuinely debated and likely multifactorial. The gut-brain axis hypothesis — that the immature gut microbiome of a colicky infant sends distress signals through the nervous system that manifest as prolonged crying — has gained significant support in recent years. Research has consistently found that colicky infants have a different gut microbial composition than non-colicky infants: lower levels of Lactobacillus species, higher levels of gas-producing bacteria, and evidence of increased intestinal inflammation and permeability. This gut microbiome difference is what makes probiotics a scientifically plausible intervention rather than simply a wellness trend.

The Science Behind Probiotic Drops for Newborns With Colic

The research on probiotic drops for newborns and colic has expanded considerably over the past fifteen years, and while the field is not yet at the point of definitive consensus, the weight of evidence in favor of specific probiotic strains is meaningful enough to inform clinical recommendations.

The most studied probiotic strain for infant colic is Lactobacillus reuteri DSM 17938, a specific bacterial strain derived from human breast milk that was first isolated by researchers investigating the gut microbiome of breastfed infants. Multiple randomized controlled trials have compared this specific strain — administered daily as drops — to placebo in breastfed infants with colic, and several have shown statistically significant reductions in daily crying time in the probiotic group compared to the placebo group.

A 2014 systematic review and meta-analysis published in JAMA Pediatrics analyzed the pooled data from multiple trials of L. reuteri DSM 17938 in breastfed colicky infants and found that infants receiving the probiotic cried significantly less than those receiving placebo, with the effect becoming apparent within the first week of treatment and strengthening over subsequent weeks. The magnitude of the effect was clinically meaningful — reductions in crying of sixty to ninety minutes per day in some studies — which for a family dealing with three or more hours of crying represents a substantial improvement in daily life.

However, important qualifications apply. The evidence is significantly stronger for breastfed infants than for formula-fed infants, with several studies showing little or no effect of L. reuteri in formula-fed babies with colic. The reason for this feeding-mode difference is not fully understood but may relate to differences in baseline gut microbiome composition between breastfed and formula-fed infants that affect how well the probiotic colonizes and influences the gut environment.

How Probiotics Are Thought to Work in Colicky Infants

The mechanism through which probiotic drops may reduce colic symptoms involves several pathways that are still being characterized, but the current understanding provides a coherent biological framework for the observed effects.

Restoring Microbial Balance

The gut microbiome of a colicky infant tends to be dominated by gas-producing bacterial species — Clostridium, Klebsiella, and Escherichia strains — and depleted in beneficial Lactobacillus species. This imbalance, sometimes called gut dysbiosis, promotes excessive fermentation of undigested food components, producing hydrogen and carbon dioxide gas that causes intestinal distension and pain. L. reuteri appears to partially correct this imbalance by colonizing the gut and competing with gas-producing species for available nutrients and attachment sites on the intestinal wall.

Reducing Intestinal Inflammation

Research has found elevated markers of intestinal inflammation in colicky infants compared to non-colicky controls, suggesting that local gut inflammation may contribute to the pain response that manifests as crying. L. reuteri produces a substance called reuterin that has antimicrobial properties against certain gut pathogens, and the strain also appears to reduce inflammatory signaling in the intestinal wall, which may reduce the pain sensitivity of the gut and lower the crying response to normal gut sensations that a colicky infant experiences as painful.

Influencing the Gut-Brain Axis

The gut-brain axis is the bidirectional communication pathway between the enteric nervous system — the extensive network of neurons embedded in the gut wall — and the central nervous system. Emerging research suggests that the gut microbiome influences mood, pain perception, and stress responses through this axis in ways that are increasingly well-characterized in adults and are beginning to be studied in infants. The gut microbiome produces neurotransmitter precursors including serotonin precursors, and microbial metabolites influence vagal nerve signaling between gut and brain. A gut environment shifted toward less dysbiosis by probiotic supplementation may reduce the pain signals transmitted through this axis, leading to less crying behavior.

What the Evidence Doesn't Yet Show

Honest assessment of the probiotic drops for newborns colic evidence requires acknowledging its limitations as clearly as its strengths, because parents making decisions in the difficult context of a colicky baby deserve accurate rather than inflated expectations.

The evidence base is dominated by studies of breastfed infants. As noted above, the effect in formula-fed infants is significantly less consistent, and several trials in formula-fed babies have found no statistically significant difference between the probiotic and placebo groups. This is a meaningful limitation for the large proportion of families using formula either exclusively or partially.

Study quality and consistency vary across the research. Some trials have been criticized for small sample sizes, inadequate blinding of parents and assessors, or use of crying diaries that are subject to observer bias. The most rigorous trials — using objective crying measurements, adequate blinding, and pre-registered protocols — show smaller effect sizes than less rigorous studies, suggesting some publication bias and methodological optimism may be inflating the apparent benefit in the broader literature.

The research has also focused almost entirely on L. reuteri DSM 17938 as a specific strain. There is essentially no comparable evidence base for other probiotic strains in infant colic, which means that a probiotic product marketed for colic that contains a different Lactobacillus strain, Bifidobacterium, or a multi-strain formula is not supported by the same evidence as L. reuteri DSM 17938 specifically, regardless of how persuasively it is marketed.

Choosing a Probiotic Drop for Your Newborn

If you decide to try probiotic drops based on the evidence above, strain specificity is the most important purchasing criterion. The product you choose should specify Lactobacillus reuteri DSM 17938 as its active strain — not just "Lactobacillus reuteri" generically, as DSM 17938 is a specific patented strain distinct from other L. reuteri strains that have not been studied in infant colic. BioGaia Protectis is the most widely studied commercial product containing this specific strain and is the one used in the majority of the clinical trials described above.

Dosage matters as much as strain. The dose used in the research is one hundred million (10^8) colony-forming units per day, which corresponds to five drops of BioGaia Protectis daily. Products that contain the correct strain at a lower dose than studied may not produce the same effects, and there is no evidence that higher doses improve outcomes.

Probiotic drops should be given consistently at the same time each day — many families find the pre-feed routine works well — rather than intermittently. The benefits observed in research studies accumulated over days to weeks of daily supplementation, not immediately after a single dose. If you're going to try probiotics for colic, a minimum trial of two to three weeks at the correct daily dose is needed to assess whether the intervention is producing any benefit.

Probiotics in the Context of a Broader Colic Management Approach

Probiotic drops are most effective when used as one component of a broader approach to managing a colicky newborn rather than as a standalone solution. The honest expectation for even the most evidence-supported probiotic intervention is a reduction in crying time, not elimination — and a reduction that helps some babies more than others.

Carrying and physical closeness is one of the most consistently effective non-pharmacological approaches to colic management, supported by both research and centuries of parenting experience. A baby wrap sling carrier keeps a colicky baby upright, close to the caregiver's body warmth and heartbeat, and gently moving — all of which have documented calming effects. Many families dealing with colic find babywearing during the peak crying window of the late afternoon and evening dramatically reduces the intensity of crying episodes even when it doesn't eliminate them.

Sound environment management is another evidence-supported approach. A baby sound machine producing continuous white noise replicates the intrauterine sound environment that many newborns find calming and can reduce the contrast between ambient silence and the environmental triggers that seem to worsen crying in colicky infants. The LED star projector can also be useful during evening colic peaks, providing gentle visual stimulation that can briefly capture a crying infant's attention and interrupt the escalating cry cycle. Read more about the full range of sleep and sound strategies in our guide to best white noise machines for babies.

For parents who are also dealing with reflux alongside colic — the two frequently co-occur and are sometimes confused — our guide to choosing the right baby carrier for a newborn with reflux covers positioning strategies that address both conditions simultaneously. If feeding is a suspected contributor to the crying, our guide to best non-toxic baby bottles for breastfed newborns covers bottle selection that minimizes air swallowing and digestive discomfort during feeds.

Safety Considerations for Probiotic Drops in Newborns

Probiotic supplementation with L. reuteri DSM 17938 has an excellent safety record in healthy term infants across the clinical trials conducted to date. No serious adverse events attributable to the probiotic have been reported in the research literature, and the strain has been used in millions of infants globally without documented safety concerns in the healthy term population.

However, probiotic supplementation is not appropriate for all infants, and several situations warrant discussion with a pediatrician before starting. Preterm infants — particularly those born before thirty-two weeks gestation — have a different gut microbiome and immune status that makes probiotic supplementation a more complex intervention that should be managed by the neonatal team rather than undertaken independently. Infants with any immune compromise, including those receiving immunosuppressive treatment, should not receive probiotics without medical oversight. And any infant whose crying pattern is severe, worsening, or accompanied by other symptoms — fever, blood in stool, poor feeding, poor weight gain — should be evaluated medically before any intervention is attempted, because these features suggest a cause of crying that is not developmental colic.

For healthy term infants whose pediatrician has confirmed a diagnosis of colic after ruling out other causes, L. reuteri DSM 17938 at the studied dose is a reasonable, evidence-informed addition to a management approach — particularly for breastfed babies.

Realistic Expectations and a Final Word

The honest answer to whether probiotic drops for newborns really help with colic is: for breastfed infants specifically, the evidence suggests they probably do, with a meaningful reduction in daily crying time for many babies. For formula-fed infants, the evidence is considerably less compelling. For all infants, the effect is a reduction in severity rather than a cure, and it emerges gradually over days to weeks rather than immediately.

Colic is temporary. The three-to-four-month natural resolution point arrives for the vast majority of babies regardless of what interventions are tried. The value of evidence-supported interventions like L. reuteri probiotics, babywearing with a baby wrap sling carrier, and white noise is not that they solve colic permanently — it's that they make the weeks until natural resolution more manageable for the baby, more sustainable for the parents, and less likely to create the secondary sleep and feeding disruptions that can persist after the colic itself has resolved.

If your baby is in the thick of a colic period right now, the most important thing to know is that it ends — and that you're not alone in finding it one of the hardest things you've faced as a parent.