Colic is not a disease your baby has. It is a label for a healthy, well-fed baby who cries far more than seems reasonable, for no cause anyone can find. The classic definition is crying for more than 3 hours a day, more than 3 days a week, for more than 3 weeks.6
That distinction matters, because it changes what you are actually dealing with. You are not failing to fix a problem. You are living through a hard, self-limiting phase that about 1 in 5 babies goes through and that almost always ends by 3 to 4 months.1
This guide covers what colic is, why it happens, which of the many remedies on the shelf actually hold up, and the specific signs that mean the crying is not colic and needs a doctor.
Key Takeaways
Colic is defined by the Rule of 3: crying over 3 hours a day, over 3 days a week, for over 3 weeks, in an otherwise healthy, thriving baby.6
It affects about 1 in 5 babies, usually starts around 2 weeks, peaks near 6 weeks, and resolves by 3 to 4 months.1
The cause is genuinely unknown. Colic sits at the top of the normal infant crying curve rather than being a separate illness.10
Most shelf remedies do not beat placebo. Simethicone (gas drops) performed no better than placebo in a trial, and the NHS says anti-colic drops and herbal supplements are not recommended.72
Probiotics may help, but mainly in breastfed babies, and not reliably in formula-fed ones.89
Colic is a diagnosis of exclusion. Fever under 3 months, vomiting, blood in stool, or poor feeding are not colic and need a doctor.25
Never shake a baby. If you feel at the end of your rope, put the baby down safely and walk away for a few minutes.11
Table of Contents
What Colic Actually Is
Colic is a description, not a diagnosis in the usual sense. It describes excessive, hard-to-soothe crying in a baby who is otherwise healthy, feeding well, and growing normally. There is no lab test for it and no single known cause.25
The most cited definition is Wessel’s Rule of 3, from 1954: crying or fussing for more than 3 hours a day, on more than 3 days a week, for more than 3 weeks.6 More recent clinical criteria (Rome IV) drop the stopwatch for everyday diagnosis and focus on recurrent, prolonged crying in a baby under 5 months with no illness and no failure to thrive.13
Here is the reframe that helps most parents. Every baby cries more in the early weeks, on a remarkably consistent curve: crying climbs from around 2 weeks, peaks near 6 weeks, then declines by 3 to 4 months. Colic is not a different thing from this curve, it is the upper tail of it. Your baby is on the same road as everyone else, just further along the crying end of it.10
Why Colic Happens (and Why Nobody Is Sure)
The honest answer is that the cause is unknown and probably not one thing. Researchers have proposed an immature gut, an evolving gut microbiome, sensitivity to cow’s milk protein in a minority, and differences in how some babies handle stimulation and self-regulate. None of these explains all cases, and colicky babies are, by definition, physically healthy.413
Food sensitivity is worth a specific mention because it gets blamed a lot. It accounts for less than 5 percent of colicky crying. For most babies, cutting foods or switching formula is not the answer, though a genuine cow’s milk protein allergy is worth ruling out with your doctor if there are other signs.112
This uncertainty is frustrating, but it is also freeing. If there is no clear cause, then the crying is not something you triggered or can be expected to switch off. That takes a specific kind of guilt off the table.
The Hard Nights Colic Sits On Top Of
Colic lands on a baseline that is already exhausting for most families. In our State of Baby Sleep 2026 report, drawn from 74,379 parents across 112 countries, night waking is heaviest in the same early months when colic peaks.
Babies waking 3 or more times a night, by age
The colic weeks overlap the hardest stretch for night sleep
48.8 percent of babies aged 0 to 3 months woke three or more times a night (n=3,259), and 46.4 percent of parents described themselves as exhausted. We mention it because exhaustion is exactly the state in which shaking a baby becomes a risk. If you are at the edge, put your baby down safely and step away. The crying is temporary. That decision is not.
What Actually Helps
Soothing techniques will not cure colic, because there is nothing to cure, but they can take the edge off a given evening and, just as important, give you something to do. The measures with the best support are simple and free.2
Motion and closeness: holding, gentle rocking, a carrier or a walk. Contact soothes many babies even when nothing “fixes” the crying.
White noise or a calm, low-stimulation environment, especially during the evening witching hours.
Offering a feed or a pacifier, and checking the basics (diaper, temperature, not too hot).
Taking shifts. Handing the baby to a partner or trusted adult for 20 minutes is a legitimate strategy, not a failure.
For the evening crying specifically, our guide to the witching hour goes deeper, and if the crying comes with a lot of squirming and gas, relieving baby gas covers what does and does not work there.
Crying all evening and nobody is sleeping?
Colic passes, but the survival weeks are brutal. Get a plan built around your baby’s stage.
This is the part most colic pages skip, because it is not what the products on the shelf want you to hear. The evidence for most colic remedies is weak or negative.
Simethicone, the active ingredient in most gas drops, was tested against placebo in a randomized trial and worked no better than placebo. Improvement happened at the same rate whether babies got the drops or a dummy.7 A Cochrane review of pain-relieving agents for colic found the trials small and generally low quality, with no reliable winner.3
Gripe water and herbal drops are not regulated as medicines, their formulations vary, and the NHS states plainly that anti-colic drops, herbal and probiotic supplements are not recommended and there is no good evidence they help.2 Spinal manipulation and cranial osteopathy have little evidence and carry their own risks, so they are not a safe substitute.
Probiotics are the one partial exception, and even there the picture is narrow. An individual-participant meta-analysis found Lactobacillus reuteri reduced crying in breastfed colicky infants, but the evidence did not support a benefit in formula-fed babies.8 A large community trial that included formula-fed infants found no overall benefit and even a signal of more crying in the formula-fed group.9 So probiotics are worth a conversation with your doctor if you are breastfeeding, and not a reliable fix otherwise.
When Crying Is Not Colic: Red Flags
Colic is a diagnosis of exclusion, which means the label only fits after illness has been ruled out. A truly colicky baby feeds well, gains weight, and is healthy between crying bouts. The following are not colic and need medical attention.25
Call the doctor or seek urgent care if your baby
Is under 3 months and has a fever of 100.4F (38C) or higher.2
Has forceful or projectile vomiting, green or bile-stained vomit, or blood in the stool or vomit.5
Is feeding poorly, not gaining weight, or seems floppy, listless, or hard to rouse.5
Has fewer than 6 wet diapers a day or other signs of dehydration.2
Is breathing fast (more than 60 breaths a minute), grunting, or working hard to breathe.
Has a cry that is high-pitched, weak, or simply does not sound like their normal cry.2
There is one more piece of safety that colic pages must not skip. Relentless crying is a known trigger for shaking a baby, and shaking causes catastrophic brain injury. This is the reasoning behind the Period of PURPLE Crying education: the crying peaks around 2 months, resists soothing, and is normal and temporary.11 If you feel yourself getting to the edge, it is safe and right to put your baby down on their back in an empty crib, close the door, and take a few minutes. A baby crying alone briefly is safe. A shaken baby is not.11
Frequently Asked Questions
What is the Rule of 3 for colic?
It is the classic definition of colic: crying or fussing for more than 3 hours a day, on more than 3 days a week, for more than 3 weeks, in a baby who is otherwise healthy and feeding and growing well. It was described by Wessel in 1954 and is still widely used.
When does colic peak and when does it end?
Colic usually starts around 2 weeks of age, peaks near 6 weeks, and eases off and resolves by about 3 to 4 months. This tracks the normal infant crying curve, which rises and falls on the same timeline in all babies.
Do gas drops or gripe water work for colic?
The evidence says mostly no. Simethicone (the main ingredient in gas drops) worked no better than placebo in a randomized trial, and the NHS says anti-colic drops, herbal and probiotic supplements are not recommended with no good evidence they help. Probiotics may help breastfed babies specifically, but not reliably formula-fed ones.
What causes colic?
No one knows for certain, and it is likely not a single cause. Proposed factors include an immature gut, the developing microbiome, and differences in how some babies handle stimulation. Food sensitivity accounts for under 5 percent of cases. By definition colicky babies are physically healthy.
How is colic different from normal crying?
It is not a different kind of crying, it is more of it. Every baby cries on a curve that peaks around 6 weeks. Colic is the upper end of that same curve, defined by crossing the Rule of 3 threshold, in a baby who is otherwise well.
When should I take a crying baby to the doctor?
Seek care for a fever of 100.4F (38C) under 3 months, projectile or green vomiting, blood in stool, poor feeding or weight gain, fewer than 6 wet diapers a day, fast or labored breathing, or a weak or high-pitched cry. These are red flags that the crying is not colic.
In the thick of the crying weeks?
Get a personalized plan that meets your baby where they are and adapts as the crying phase passes.
Biagioli E, Tarasco V, Lingua C, Moja L, Savino F. Pain-relieving agents for infantile colic. Cochrane Database Syst Rev. 2016;9(9):CD009999. https://pubmed.ncbi.nlm.nih.gov/27631535/
Wessel MA, Cobb JC, Jackson EB, et al. Paroxysmal fussing in infancy, sometimes called colic. Pediatrics. 1954;14(5):421-435. https://pubmed.ncbi.nlm.nih.gov/13214956/
Metcalf TJ, Irons TG, Sher LD, Young PC. Simethicone in the treatment of infant colic: a randomized, placebo-controlled, multicenter trial. Pediatrics. 1994;94(1):29-34. https://pubmed.ncbi.nlm.nih.gov/8008533/
Sung V, DAmico F, Cabana MD, et al. Lactobacillus reuteri to Treat Infant Colic: A Meta-analysis. Pediatrics. 2018;141(1):e20171811. https://pubmed.ncbi.nlm.nih.gov/29279326/
Sung V, Hiscock H, Tang ML, et al. Treating infant colic with the probiotic Lactobacillus reuteri: double blind, placebo controlled randomised trial. BMJ. 2014;348:g2107. https://pubmed.ncbi.nlm.nih.gov/24690625/
Iacovou M, Ralston RA, Muir J, Walker KZ, Truby H. Dietary management of infantile colic: a systematic review. Matern Child Health J. 2012;16(6):1319-1331. https://pubmed.ncbi.nlm.nih.gov/21710185/
