Colicky describes an infant who cries intensely and inconsolably for extended periods, with no identifiable cause like hunger, a wet diaper, or illness. The formal threshold, known as the “rule of three,” is crying more than three hours per day, more than three days per week, for longer than three weeks. About 20% of infants experience colic, and while it’s stressful for everyone involved, it’s a benign condition that resolves on its own.
When Colic Starts and Stops
Colic typically begins between the third and sixth week after birth. Crying episodes tend to intensify over the following weeks, often peaking around six to eight weeks of age. Most babies outgrow colic by three to four months. The pattern is remarkably consistent: it arrives suddenly, dominates a few exhausting weeks, and then gradually fades without any lasting harm to the baby.
What Colicky Crying Looks and Sounds Like
Colicky crying is distinct from normal infant fussiness. It’s loud, high-pitched, and can sound like the baby is screaming or in pain. The episodes often arrive at predictable times, most commonly in the late afternoon or evening, and they resist the usual soothing techniques that work for regular crying.
During an episode, you may notice physical signs that look alarming but are characteristic of colic: clenched fists, stiff or pulled-up legs, an arched back, a tense belly, and facial flushing. The baby may remain irritable even after the intense crying winds down. Between episodes, colicky babies are otherwise healthy. They feed normally, gain weight, and hit their developmental milestones.
What Causes It
No single cause has been identified, which is part of what makes colic so frustrating. Several theories have strong evidence behind them, and the reality is likely a combination of factors that vary from baby to baby.
One leading explanation centers on the gut. Newborns are still building their intestinal bacteria, and colicky infants tend to have less diversity in their gut microbiome. Specifically, they show lower levels of beneficial bacteria (like Bifidobacteria) and higher levels of bacteria that promote inflammation. This imbalance may irritate the gut lining and trigger discomfort. Colicky infants also show higher levels of a serotonin byproduct in their urine. Since the gut produces serotonin and that chemical influences mood and behavior, elevated levels could contribute to the distress.
An immature digestive system also plays a role. Babies in the first few months are still learning to process food, move gas through their intestines, and coordinate the muscles involved in digestion. That tense belly and pulled-up legs during crying episodes suggest genuine abdominal discomfort for at least some colicky babies.
Soothing Techniques That Help
No single remedy works for every colicky baby, but several approaches have enough evidence and parental support to be worth trying systematically.
Rhythmic motion and gentle pressure on the belly are among the most reliable comforts. Carrying your baby in a front carrier combines body contact with movement. Laying the baby tummy-down across your knees and gently rubbing their back puts pressure on the abdomen, which can ease gas-related discomfort. If the baby falls asleep in this position, always move them to their back in the crib.
White noise is surprisingly effective. A fan, clothes dryer running in the next room, vacuum cleaner, or a dedicated white noise machine can calm a screaming baby when nothing else works. Swaddling in a thin blanket and offering a pacifier are two other low-effort strategies worth trying early.
Dietary changes can make a difference for some breastfed babies. Eliminating dairy from the nursing parent’s diet is the most commonly recommended first step, since cow’s milk proteins pass into breast milk and can irritate a sensitive infant gut. Caffeine, onions, and cabbage are other potential triggers. The key is to remove only one food at a time and wait about two weeks before judging whether it helped. For formula-fed babies, switching to a protein hydrolysate formula (where the milk proteins are already broken down) is worth discussing with your pediatrician.
Probiotics for Breastfed Babies
A specific probiotic strain, Lactobacillus reuteri DSM 17938, has strong evidence behind it for breastfed colicky babies. A meta-analysis published in the journal Pediatrics found that breastfed infants given this probiotic were almost twice as likely to improve compared to those given a placebo, with crying time dropping by about 25 minutes per day after three weeks. The number needed to treat was just 2.6, meaning roughly three out of every three babies treated experienced meaningful relief. The effect was insignificant in formula-fed infants, so this is specifically a tool for breastfeeding families.
Overfeeding Can Make It Worse
It’s natural to offer the breast or bottle every time a baby cries, but overfeeding can add to the discomfort. A stomach that’s too full creates more gas and more pressure. A good general rule is to wait at least two to two and a half hours from the start of one feeding to the start of the next. This gives the stomach time to empty and reduces the chance that excess milk is contributing to the problem.
Signs That It’s Not Colic
Colic is a diagnosis of exclusion, meaning it applies only after other causes of crying have been ruled out. A few red flags suggest something beyond colic is going on: fever, projectile vomiting, poor weight gain or refusal to feed, blood in the stool, or a sudden onset of inconsolable crying in a baby who was previously calm. Rapid increases in head size or any unexplained bruising or injuries also warrant immediate evaluation. A colicky baby, by contrast, is thriving between episodes. They eat well, gain weight steadily, and have no other symptoms.
The Toll on Parents
Colic is technically harmless to the baby, but its effect on parents is real and measurable. In one study, mothers of colicky infants scored significantly higher on a standard depression screening tool (averaging 10.2) compared to mothers of non-colicky babies (averaging 6.3). Nearly a quarter of mothers with colicky infants showed scores suggesting possible postpartum depression, compared to 10% in the non-colic group.
The relentless crying can erode confidence, strain relationships, and create a sense of helplessness that compounds sleep deprivation. If you’re caring for a colicky baby, stepping away for a few minutes when the crying becomes overwhelming is not just acceptable, it’s important. Putting the baby down safely in their crib and taking a brief break in another room is a well-recognized coping strategy. Colic ends. The weeks feel interminable while you’re in them, but the vast majority of cases resolve completely by four months.