The hallmark symptom of colic is intense, inconsolable crying that lasts three or more hours a day, happens at least three days a week, and continues for three or more weeks. This pattern, sometimes called the “rule of three,” is what separates colic from normal newborn fussiness. Colic affects roughly 10% to 40% of infants worldwide, and despite how alarming it feels, babies with colic continue to grow and gain weight normally.
What Colic Crying Sounds Like
Colic crying is noticeably different from a hungry cry or a tired cry. It tends to be higher-pitched, louder, and more intense than other types of infant crying. The episodes often come on suddenly, without an obvious trigger, and your baby may be nearly impossible to console no matter what you try.
The crying clusters heavily in the evening and can stretch until midnight. Many parents describe the pattern as predictable: their baby is relatively calm during the day, then begins screaming at roughly the same time each night. These episodes can last anywhere from one to several hours at a stretch.
Physical Signs During an Episode
While your baby is crying, you’ll likely notice a set of physical changes that look like pain or discomfort. Common signs include:
- Clenched fists held tight against the body
- Drawn-up legs pulled toward the belly
- A tense, hard abdomen that feels tight when you touch it
- An arched back as your baby stiffens during crying
- A flushed or reddened face from the intensity of the screaming
Your baby may also pass gas or seem restless and squirmy between bouts. These signs can look a lot like a stomachache, which is one reason researchers have long suspected the gut plays a role in colic.
When It Starts, Peaks, and Stops
Colic most often begins late in the first month of life. It ramps up quickly and is typically at its worst around six weeks of age. That peak can feel relentless, but there’s a clear endpoint: episodes begin to taper off after three to four months, and symptoms resolve for most babies by five to six months.
This timeline holds regardless of whether a baby is breastfed or formula-fed. If your baby’s excessive crying starts much earlier than three weeks, starts suddenly after weeks of calm behavior, or persists well past six months, something other than colic may be going on.
What Causes the Symptoms
No single cause has been pinpointed, but the strongest current evidence points to the gut. Research published in The Journal of Pediatrics found that babies with colic have higher levels of a protein marker for intestinal inflammation, regardless of whether they’re breastfed or formula-fed. These infants also showed a different balance of gut bacteria compared to non-colicky babies, specifically fewer of the beneficial bacteria that help regulate the immune system and more of certain bacteria linked to inflammation.
Other contributing factors that researchers have identified include milk protein sensitivity, maternal stress during pregnancy, and an immature nervous system that makes some infants more reactive to stimulation. In many cases, it’s likely a combination of several of these factors rather than a single trigger.
Colic vs. Cow’s Milk Allergy vs. Reflux
Colic, cow’s milk protein allergy, and reflux share overlapping symptoms, which makes them easy to confuse. The key differences come down to a few specific signs.
A baby with colic cries intensely but continues to feed well and gain weight on a normal curve. A baby with cow’s milk protein allergy often has additional symptoms beyond crying: skin rashes, vomiting, diarrhea, wheezing or coughing, and slow weight gain. Reflux typically involves frequent spitting up or vomiting after feeds, arching during or right after eating, and feeding refusal.
If your baby has vomiting, a rash, wheezing, diarrhea, or is not gaining weight, those symptoms point away from colic and toward an allergy or another medical issue that needs evaluation.
Red Flags That Aren’t Colic
Some patterns of crying signal something more urgent. Crying that starts very suddenly in a baby who was previously calm and content can indicate a medical problem like a trapped hernia, an intestinal blockage, an infection, or even a hair wrapped tightly around a finger or toe (a surprisingly common cause of sudden screaming). Other warning signs include poor feeding, failure to gain weight, a bulging soft spot on the head, unexplained bruising, or any sign that your baby seems genuinely unwell between crying episodes, such as fever or lethargy.
The distinguishing feature of colic is that between episodes, the baby looks completely healthy. They feed, sleep, and interact normally. If that’s not the case, the crying likely has a different cause.
Soothing Techniques That Help
There is no guaranteed fix for colic, but several approaches can reduce the intensity or duration of episodes for many babies. Gentle tummy rubs, placing your baby on their stomach across your lap for a back rub, and warm baths can help relax a tense abdomen. White noise, whether from a dedicated machine, a fan, or even a clothes dryer running in a nearby room, often calms a screaming baby when nothing else works. Dimming the lights and reducing stimulation during evening hours can also prevent episodes from escalating.
Swaddling with room for the legs to move freely, rhythmic rocking, and keeping a consistent feeding schedule (either on demand or at set intervals) give some babies relief. No single method works for every infant, so most parents end up cycling through several strategies to find what their baby responds to.
The Toll on Parents
Colic is temporary for the baby but can be genuinely damaging for caregivers. Mothers of colicky infants score significantly higher on measures of depression, anxiety, and stress compared to mothers of babies without colic. The relentless crying is linked to exhaustion, feelings of guilt, disrupted sleep, and in some cases, intrusive thoughts about harming the baby. Research also shows the relationship runs both directions: parental stress can worsen an infant’s fussiness, creating a cycle that’s hard to break.
If you’re caring for a colicky baby and feel overwhelmed, putting the baby down in a safe space like a crib and stepping away for a few minutes is not neglect. It’s a recognized and necessary coping strategy. Having a partner, family member, or friend take over for even short stretches can make a significant difference in getting through the worst weeks.