Colic typically begins late in the first month of life, peaks around six weeks of age, and resolves between three and six months. For most infants, the worst of it eases after three to four months. While those weeks can feel endless for exhausted parents, colic is temporary and follows a remarkably predictable arc.
The Typical Colic Timeline
Colic follows a pattern that pediatricians sometimes call the “colic curve.” Symptoms usually appear when a baby is two to three weeks old, then intensify steadily. The peak hits around six weeks, when crying episodes are longest and most frequent. After that, the intensity gradually tapers. By three to four months, most babies are noticeably better, and by six months, colic has resolved in nearly all cases.
During the peak weeks, a colicky baby may cry for three or more hours a day, often in the late afternoon or evening, on three or more days per week. The crying tends to start and stop without an obvious trigger. Your baby may clench their fists, arch their back, pull their legs toward their belly, and turn red in the face. Between episodes, they’re usually feeding well and gaining weight normally.
Colic affects roughly 10 to 30 percent of infants worldwide, so if your baby has it, you’re far from alone. It occurs equally in breastfed and formula-fed babies, in firstborns and later children, and across all demographics.
Why Colic Happens
No one has pinpointed a single cause. The leading theories involve the digestive system, the nervous system, or some combination of both. One prominent explanation points to the immaturity of a newborn’s gastrointestinal tract. A baby’s gut is still developing its bacterial ecosystem in those early weeks, and colicky infants tend to have lower microbial diversity, more gas-producing bacteria, and higher levels of inflammatory markers in their intestines compared to non-colicky babies.
Another theory focuses on the nervous system. Young infants are still learning to process sensory input, and some babies may become overwhelmed more easily, especially by the end of a stimulating day. This could explain why colic episodes cluster in the evening hours. The fact that colic resolves around three to four months, right when a baby’s nervous system reaches a new level of maturity, supports this idea. In reality, colic probably results from several factors converging during a narrow developmental window, then resolving as the baby’s body catches up.
What Actually Helps During Colic
No single intervention reliably stops colic, but several strategies can reduce crying and make episodes more manageable. The most studied non-medical approach combines five soothing techniques: swaddling, holding the baby on their side or stomach (while awake and supervised), making a shushing sound, gently swinging or rocking, and offering something to suck on. Research consistently finds this combination is the most effective approach, particularly for calming overstimulated infants. Swaddling alone reduces the startle reflex that can jolt a baby awake, while rhythmic shushing and gentle motion have significant calming effects.
For formula-fed babies, switching to a hypoallergenic (hydrolyzed) formula has shown some benefit in studies, though the evidence isn’t strong. Soy-based formulas may also reduce the duration of symptoms. If you’re breastfeeding and suspect a food sensitivity, some mothers find that eliminating cow’s milk protein from their own diet helps, though this is worth discussing with your pediatrician before making dietary changes.
One specific probiotic strain has the strongest clinical evidence behind it. In a controlled trial, breastfed colicky infants given this probiotic cried an average of 35 minutes per day after three weeks, compared to 90 minutes per day in the group that received a placebo. That’s a meaningful difference, though the benefit has been demonstrated more clearly in breastfed infants than in formula-fed ones.
Signs That It’s Not Colic
Colic is a diagnosis of exclusion, meaning it applies when there’s no other medical explanation for the crying. A truly colicky baby is otherwise healthy: feeding well, gaining weight, and looking normal between episodes. Certain signs suggest something else is going on and warrant a prompt medical evaluation.
- Fever or appearing unwell between crying episodes could indicate an infection.
- Vomiting, bloody stools, or poor weight gain may point to a cow’s milk protein intolerance, reflux, or a bowel problem.
- Sudden onset of pale, floppy episodes with legs drawing up and blood in the stool is a pattern seen in intussusception, a bowel emergency.
- Crying only during feeds with refusal to suck can signal oral thrush or painful reflux.
- Swelling or redness in the groin or scrotum may indicate a hernia or, in boys, testicular torsion.
- Pain with specific movements, such as screaming during diaper changes, could suggest a fracture or bone infection, especially in a baby who isn’t yet mobile.
- Asymmetric startle reflex (one arm doesn’t move normally when startled) can be a sign of a clavicle fracture from delivery.
One easily overlooked cause of inconsolable crying is a hair tourniquet, where a strand of hair or thread wraps tightly around a toe, finger, or the penis, cutting off circulation. If your baby is crying and you can’t find a reason, check all their digits carefully.
The Toll on Parents
Colic doesn’t just affect babies. The relentless crying takes a real psychological toll on caregivers. Research has linked postpartum depression with an increased risk of infant colic, and the relationship likely runs in both directions: a depressed parent may perceive more distress, while weeks of inconsolable crying can trigger or worsen depression. Interestingly, one study found that the happiness a mother reported in her partner relationship during and after pregnancy was the strongest predictor of lower colic risk, even stronger than postpartum depression status.
If you’re in the thick of colic, protecting your own mental health isn’t a luxury. Handing the baby to a partner, family member, or friend and stepping away for 15 minutes is completely reasonable. Frustration during prolonged crying is normal. Acting on that frustration is dangerous. Shaking a baby can cause permanent brain damage or death, and the peak period of shaken baby syndrome overlaps almost exactly with the peak period of colic. If you feel yourself reaching a breaking point, putting the baby down in a safe place and walking into another room for a few minutes is always the right call.
What Happens After Colic Resolves
For most children, colic leaves no lasting physical effects. However, a large study published in Archives of Disease in Childhood found that infants who had colic scored slightly lower on developmental assessments at age five and had somewhat higher rates of internalizing problems (anxiety, withdrawal, emotional reactivity) at both three and five years of age compared to children who didn’t have colic. The differences were statistically significant but small. Researchers flagged colic and early sleep problems as risk factors worth monitoring, not as guarantees of later difficulties.
This doesn’t mean colic causes behavioral problems. It may simply be that the same nervous system sensitivity that produces colic in infancy also shows up in subtly different ways as a child grows. Either way, the vast majority of formerly colicky babies develop normally and show no distinguishable differences from their peers by school age.