When Do Babies Get Colic? Facts

Colic usually shows up in the first few weeks of life. Most babies who develop it start showing signs between 2 and 6 weeks of age. It typically peaks around 6 weeks, improves steadily after that, and has usually resolved by 3 to 4 months.

That timeline is one of the few things about colic that researchers agree on. What causes it, and why some babies get it and others don’t, is still not fully understood. Here is what the evidence actually supports.

When Do Babies Get Colic?

Colic most often begins between 2 and 6 weeks of age in full-term babies. It is rare in the first week of life. Preterm babies tend to start later, usually closer to their original due date rather than their birth date.

The pattern is distinctive. Crying episodes cluster in the late afternoon and evening. They often start and stop at roughly the same time each day. The crying is intense and hard to soothe, and the baby may pull their legs up, clench their fists, and turn red in the face.

It gets worse before it gets better. Fussing and crying typically peak around 6 weeks of age, then gradually decline over the following weeks. By 3 to 4 months, most babies have outgrown it. Some parents notice it fading closer to 12 weeks. Others see it linger a little past 4 months. Both fall within the normal range.

One detail that surprises many parents: all babies cry more in the first few months than at any other time in infancy. Crying that increases in the early weeks and then settles is a normal developmental curve. Colic is the extreme end of that curve, not a separate disease process.

How Is Colic Defined?

Clinicians diagnose colic by the pattern of crying, not by a lab test or scan. There is no blood test for colic and no physical finding that confirms it.

The most widely used definition comes from a set of criteria known as the Wessel criteria, developed in the 1950s. It describes colic as crying for more than three hours a day, more than three days a week, for more than three weeks, in an otherwise healthy, well-fed baby.

That definition has been criticized for being too strict. Many babies who cry intensely for shorter periods still worry their parents, and some clinicians use looser criteria in practice. A more recent approach focuses on whether the crying is excessive for the baby’s age and whether parents feel it is a problem. This shift matters because it recognizes that the distress is real even when a baby does not meet the classic three-three-three rule.

What colic is not: it is not the same as a medical condition causing pain. Babies with colic eat, gain weight, and develop normally. If a baby is not feeding well, is losing weight, or has other symptoms, that points toward a different cause and needs medical assessment.

What Causes Colic?

No single cause has been confirmed. Research has pointed at several possible contributors, and the honest position is that the evidence remains mixed.

• Gut development. The digestive system and gut bacteria are still maturing in the first months. Some studies suggest differences in gut bacteria between babies with and without colic, but the findings are not consistent enough to explain the condition.
• Feeding and swallowing air. Swallowed air and feeding difficulties can contribute to discomfort. Some babies with colic seem to swallow more air during feeds, though this does not account for all cases.
• Nervous system development. Some researchers describe colic as a normal stage of brain and nervous system maturation, where babies are more reactive to stimulation and less able to self-soothe. This idea fits the predictable timing and the fact that it resolves on its own.
• Family and environmental factors. Some studies have looked at parental stress, maternal smoking, and feeding method. Results vary, and none of these has been established as a cause.

What has not held up: the idea that colic is caused by a specific food allergy in most babies, or that it reflects bad parenting. Neither is supported. Colic happens in breastfed and formula-fed babies at similar rates. It happens in firstborns and later children. It is not a sign that a parent is doing something wrong.

What Are the Signs of Colic?

The main sign is intense, prolonged crying in an otherwise healthy baby. The crying often has a high-pitched, frantic quality and is hard to stop with the usual soothing.

Other common signs include:

• Pulling the legs up toward the belly and arching the back
• Clenched fists and a red, tense face
• A hard, distended belly
• Passing gas frequently
• Crying that worsens in the evening
• Brief periods of calm followed by more crying

These signs can look like pain, and many parents describe it that way. Whether colic actually involves pain is debated. Some researchers argue the behaviors reflect normal nervous system development rather than discomfort. What is clear is that the distress is real for both the baby and the family.

When Should You Call a Doctor?

Colic itself is not dangerous, but some conditions that mimic it are. Certain symptoms mean a baby needs to be seen promptly, and parents should not assume every crying spell is colic.

Seek medical advice if a baby:

• Has a fever
• Is not feeding well or is losing weight
• Vomits forcefully or repeatedly
• Has blood in the stool
• Seems unusually sleepy or very difficult to wake
• Has a swollen or tender belly
• Shows changes in breathing or skin color
• Has crying that starts suddenly and sounds different from usual

These signs can point to conditions that need evaluation, such as feeding problems or infections. A clinician can tell the difference. When in doubt, call.

What Helps With Colic?

No treatment reliably cures colic. The evidence for most interventions is limited, and many widely used approaches have not been confirmed in large human trials. What follows is what the evidence supports, and what it does not.

Soothing techniques are the mainstay. Swaddling, gentle rocking, white noise, and holding a baby upright after feeds are commonly used and generally considered low-risk when done safely. They do not stop colic, but they can reduce distress. Swaddling should always be done with attention to safe sleep practices, and babies should not be left to sleep swaddled once they can roll.

Feeding adjustments are sometimes suggested. For formula-fed babies, some clinicians recommend trying a different formula, though the evidence for hydrolyzed formulas in unselected babies with colic is mixed. For breastfed babies, changing the mother’s diet is widely done but not strongly supported by trials. Any feeding change should be discussed with a clinician, especially in very young infants.

Probiotics have received attention, particularly certain strains. Some studies suggest a possible benefit in breastfed babies, but results vary and the evidence is not strong enough to make a general recommendation. No clinical guidelines currently recommend probiotics as a standard treatment for colic.

What to be cautious about. Simethicone, gripe water, and herbal remedies are widely sold. Evidence for simethicone is weak. Herbal products are not standardized and some contain ingredients that are not appropriate for infants. No study has confirmed that these products cure colic. Parents should check with a clinician before giving any product to a newborn.

The Effect on Parents

Colic is hard on families. Prolonged infant crying is linked to parental exhaustion, stress, and in some cases depression. This is a real part of the condition and worth naming.

If a parent feels overwhelmed, it is important to put the baby down safely in the crib and step away for a few minutes. Never shake a baby. Shaking can cause serious injury or death. Taking a break is not failure; it is a safety measure.

Support helps. Asking a partner, family member, or friend to take a turn during the evening crying hours can make a real difference. Talking to a clinician about stress or low mood is appropriate and not a sign of weakness.

The Bottom Line

Colic starts between 2 and 6 weeks, peaks around 6 weeks, and usually resolves by 3 to 4 months. Its cause is not fully understood, and no treatment reliably cures it. The crying curve is normal, and most babies outgrow it on their own.

What matters most is that parents know the difference between typical colic and warning signs that need medical attention, and that they have support during a genuinely difficult stretch.