Colic in babies is usually caused by a mix of immature digestion, extra sensitivity, and how the baby is fed and soothed, rather than one single disease. In most cases, there is no serious medical problem behind the crying, even though it can be very intense and stressful.

What doctors mean by “colic”

  • Colic is usually defined as a healthy, well-fed baby who cries a lot (often 3+ hours a day, 3+ days a week, for at least 1 week) with no clear medical cause.
  • It typically starts around 2–3 weeks of age, peaks around 6 weeks, and improves by 3–4 months.

Main suspected causes (no single culprit)

Researchers see colic as a multifactor problem: several small factors add up to lots of crying.

  • Immature digestive system
    • The gut is still developing, so muscles may spasm and move milk and gas unevenly, causing discomfort.
* Some infants show higher levels of gut hormones such as motilin, which may increase gut motility and cramping.
  • Gas and gut bacteria
    • Air swallowed during feeds and crying can lead to bloating and gas, which may make babies pull up their legs and appear in pain.
* An imbalance in gut bacteria (dysbiosis) is also suspected in some infants with colic.
  • Feeding and milk-related issues
    • Overfeeding, underfeeding, or not burping enough can all increase discomfort and crying.
* A minority of babies may react to cow’s milk proteins in formula or in the breastfeeding parent’s diet, which can worsen colic-like symptoms.

* True lactose intolerance in young infants is considered uncommon, and its link to colic is weaker.

Baby’s temperament and nervous system

  • Many experts think some babies are simply more sensitive to normal sensations, light, and sound because their nervous system is still maturing.
  • These babies can become overwhelmed by stimulation and struggle to self-soothe, which shows up as long, intense crying spells.
  • Colic has even been proposed as an early form of childhood migraine in a small subset of infants.

Family, stress, and environment

  • High levels of parental stress, anxiety, or depression are linked with more reported colic, though it is not always clear which comes first.
  • Less optimal parent–infant interaction and strained dynamics between parents have been noted more often in families with severe colic, but these patterns are not seen in all studies.
  • Stress in the home may increase a baby’s fussiness or make normal crying feel harder to manage.

What colic is usually not

  • Fewer than about 5% of babies who cry excessively have an underlying disease, such as reflux, constipation, infection, or other serious conditions.
  • However, a medical check is important to rule out problems if:
    • The baby has fever, poor feeding, vomiting, bloody stools, breathing trouble, or isn’t gaining weight.
* The crying pattern changes suddenly or “doesn’t feel right” to the caregiver.

Mini FAQ: quick answers

  • Is it my fault or my parenting?
    Evidence does not support the idea that colic is caused by “bad” parenting; it is usually a phase related to the baby’s development.
  • Is it caused by something I ate (if breastfeeding)?
    Sometimes, especially cow’s milk proteins, but not always; elimination diets are only recommended under medical guidance.
  • Will my baby grow out of it?
    For most babies, colic improves on its own by 3–4 months of age and almost always by 5–6 months.

Information gathered from public forums or data available on the internet and portrayed here.