Does your baby actually have colic?

The evidence is cautiously promising for one specific strain. Lactobacillus reuteri DSM 17938 has shown benefit in multiple randomised controlled trials, primarily in breastfed infants. A 2018 meta-analysis found it reduced crying time by an average of 51 minutes per day compared to placebo in breastfed babies. Results in formula-fed infants were less consistent. Discuss with your paediatrician before starting.

Simple reflux (posseting) is normal in most babies and does not cause the sustained distressed crying pattern seen in colic. Gastro-oesophageal reflux disease (GORD), where reflux causes pain, poor feeding, or weight loss, can cause prolonged crying that mimics colic. If your baby arches their back during feeds or vomits frequently, reflux may be contributing. Your doctor can differentiate through clinical assessment.

The Rule of 3 was established by Dr Morris Wessel in 1954 and remains the most widely used clinical definition of infant colic. A baby meets the criteria if they cry for more than 3 hours per day, more than 3 days per week, for more than 3 consecutive weeks, and are otherwise healthy and well-fed. All three conditions must be met simultaneously. Many parents describe their baby as colicky when only one or two criteria are present, which is why the formal definition matters.

Despite decades of research, no single cause of colic has been identified. Leading hypotheses include gut microbiome immaturity, temporary lactose intolerance, gut motility differences, and neurological immaturity in self-regulation systems. The gut microbiome theory has recent support: colicky infants have different gut bacterial compositions, and some respond to specific probiotic strains such as Lactobacillus reuteri. Importantly, colic is not caused by parenting style, feeding method, or anything the parent is doing wrong (Zeevenhooven et al., 2017).

Most colic begins between 2 and 3 weeks of age, peaks at 6 to 8 weeks, and resolves by 3 to 4 months. Wolke et al. (2017) found that colic prevalence drops from a peak of 25 to 40% at 6 to 8 weeks to under 5% by 4 months and under 1% by 6 months. If excessive crying persists beyond 5 months, the Rome IV criteria specify that a different evaluation is needed, as this pattern is unlikely to be colic and may indicate another condition.

Neither. The Wolke et al. (2017) meta-analysis found no significant difference in colic prevalence between breastfed and formula-fed infants. Some earlier, smaller studies suggested marginally higher rates in formula-fed babies, but these differences disappeared when controlling for other variables. Switching from breast milk to formula or vice versa is not an evidence-based treatment for colic.

Depending on the definition used, colic affects 10 to 40% of infants globally. The wide range reflects differences between the strict Wessel Rule of 3 (which captures around 10 to 15%) and broader definitions that include any prolonged inconsolable crying. All ethnic and cultural groups show similar prevalence, and the rate has remained stable over decades of research despite significant changes in feeding practices and infant care. It is one of the most common reasons for urgent paediatric consultations in the first three months.

The Wessel criteria (1954) are strict and quantitative: more than 3 hours of crying, more than 3 days per week, for more than 3 weeks. The Rome IV criteria (2016) are broader: prolonged, inconsolable crying that causes parental concern, without requiring strict hour thresholds. In practice, the Rome IV criteria capture more babies who are causing genuine parental distress, while the Wessel criteria identify only the most severe cases. Both definitions agree that colic is self-limiting and resolves without medical intervention in the vast majority of cases.