What "colic" actually means
Colic is not a disease. It is a description — a label for a pattern of crying that exceeds what we expect from a normal newborn. The most widely used definition, often called Wessel's criteria or simply the rule of three, sets the threshold at crying or fussing for more than three hours a day, on more than three days a week, for at least three weeks, in a baby who is feeding well and growing normally.
The key phrase is otherwise healthy. Colic is what clinicians call a diagnosis of exclusion: it is what remains after a doctor has confirmed the baby is gaining weight, has no infection, no reflux severe enough to explain the crying, no feeding intolerance, and no other identifiable cause. The AAP's HealthyChildren.org overview of colic stresses this point precisely because so many parents assume the crying must mean something is wrong with their care. In the vast majority of cases, nothing is.
The arc: two weeks, six weeks, four months
What makes colic bearable, once you understand it, is that it follows a remarkably consistent curve. The crying usually starts around two weeks of age, intensifies through the following month, reaches its peak at roughly six weeks, and then steadily declines until it fades, almost always by three to four months.
This curve is so reliable that researchers have a name for it: the "period of PURPLE crying," a framework developed to reassure parents that a peak of unexplained crying in early infancy is normal and time-limited. The letters stand for the features that define it — it Peaks around two months, is Unexpected, Resists soothing, produces a Pain-like face, is Long-lasting, and clusters in the late afternoon and Evening. Knowing where you are on that curve changes everything: a brutal week at six weeks is not a sign things are getting worse, it is very often the peak before the decline. The Wermom team's review of the crying-curve literature walks through how consistent this trajectory is across populations.
Why the evening?
Almost universally, colicky crying clusters in the late afternoon and evening — the so-called witching hour. The honest scientific answer is that we do not fully know why. The leading explanations are that a newborn's nervous system becomes overstimulated and dysregulated by day's end, that the gastrointestinal system is still immature, and that evening is simply when an infant's limited capacity to self-organize runs out. Note that the dominant theories point to normal developmental immaturity, not to something a parent did or fed.
What the evidence says actually helps
Because no single cause is established, no single cure exists — but several soothing strategies have reasonable support, and several popular remedies do not. The interventions worth trying are gentle, rhythmic, and low-risk:
• Rhythmic motion and sound — rocking, a stroller or car ride, white noise, or wearing the baby in a carrier. Steady rhythm mimics the womb and can interrupt the cry cycle.
• Swaddling and the "5 S's" approach — swaddle, side or stomach hold (while awake and supervised), shush, swing, and suck. Combined, these recreate the sensory environment of late pregnancy.
• A calmer sensory environment in the evening — dim lights, fewer hands, less passing-around during the witching window.
• For some formula-fed or specific cases, a feeding review — occasionally a doctor will trial a change for a suspected cow's-milk protein intolerance, but only under medical guidance, not as a first move.
Equally important is knowing what to skip. The evidence for simethicone (anti-gas) drops is weak. "Gripe water" is unregulated and unproven. Switching formulas repeatedly on your own usually causes more digestive disruption than relief. For the structured, stage-by-stage soothing playbook, many parents keep Wermom's week-by-week newborn guide open during the hard weeks.
The part nobody warns you about: the caregiver
The most under-discussed danger of colic is not to the baby — it is to the exhausted adult holding the baby. Prolonged, inconsolable crying is one of the most reliably documented triggers for caregiver desperation, and it is the leading situational trigger behind shaken-baby injuries. This is not said to frighten anyone; it is said because the single most important colic intervention is sometimes to put the baby down safely and step away.
When the crying is not "just colic"
Colic is, by definition, crying in a well baby. Certain signs mean the crying deserves a same-day medical look rather than a soothing strategy:
Call your pediatrician promptly for crying accompanied by fever, vomiting (especially green or forceful), poor feeding or refusal to eat, blood in the stool, a bulging or sunken soft spot, lethargy or unusual floppiness, a change in the cry to a weak or high-pitched sound, or any crying that begins suddenly and severely after a previously calm period. These features point away from colic and toward something that needs evaluation. The CDC's infant health resources echo that a sudden, marked change in a baby's crying or behavior always warrants a check.
Here's how Wermom App makes this 10x simpler
One of the cruelest parts of colic is that, in the thick of it, you lose all sense of the curve — every evening feels like the worst one yet, and you can't tell whether things are improving. Wermom App turns the chaos into a visible trajectory:
- Cry-and-soothe logging — tap to record a crying spell and what helped; over days, Wermom charts your baby's crying against the typical colic curve so you can actually see the peak pass.
- Witching-window pattern detection — the app surfaces when your baby's hard hours cluster, so you can plan reinforcements, dim the evening, and brace before it starts rather than be ambushed.
- Caregiver check-ins & red-flag prompts — gentle reminders to tap out and hand off, plus a clear, age-aware list of the symptoms that mean "call the doctor now" rather than "keep soothing."
The promise inside the rule of three
The rule of three is usually quoted as a definition, but it is also, quietly, a promise. Three weeks, not three years. A peak at six weeks, not a permanent state. An ending by four months that arrives whether or not you ever found the magic trick — because for most families, there is no trick, only time, rhythm, and a partner to hand the baby to. If you are in the middle of it tonight, the most accurate thing anyone can tell you is the truest: this is a phase with an end date, you are not doing it wrong, and it will pass.