Crying, colic and what the evidence supports

Infant crying peaks at a predictable point, follows a recognisable pattern, and is the trigger for the most dangerous thing that happens to babies in the first months.

The normal curve

Studies across cultures have found a consistent pattern: crying increases from birth, peaks at around six to eight weeks, and declines substantially by three to four months.

Crying clusters in the late afternoon and evening.

It frequently appears unsoothable, comes without warning, and stops without warning.

This has been described as the period of purple crying, an acronym intended to convey that it is a developmental phase rather than a fault.

Knowing the shape of the curve matters because it tells exhausted parents that the worst point is at six weeks and that it improves — which is information rather than comfort, and is more useful.

Colic

A description rather than a diagnosis.

The commonly used criteria involve crying for more than three hours a day, more than three days a week, in an otherwise healthy, thriving baby.

It affects a substantial minority of infants and resolves by three to four months.

Its cause is not established, with hypotheses including gut immaturity, microbiome differences, feeding difficulties, migraine precursors and normal variation in temperament.

Importantly, colic is a diagnosis reached after excluding other causes, which means persistent excessive crying should be assessed rather than assumed.

What to exclude

Causes of crying that need identifying.

Hunger, most commonly, including insufficient milk transfer in a breastfed baby.

Cow's milk protein allergy, which typically has other features — reflux, blood or mucus in stools, eczema, poor weight gain.

Reflux with distress, which is discussed elsewhere on this site.

Infection, including urinary tract infection which is easily missed.

A hair tourniquet around a toe, finger or the penis, which is easily missed and easily treated.

Corneal abrasion.

Constipation.

Fracture, in an unwell or distressed baby.

Tongue tie affecting feeding.

And in a baby who is also feeding poorly, unwell or febrile, serious illness.

Any baby crying inconsolably and behaving unusually should be seen.

What has evidence

Less than the market suggests.

Holding and carrying: increased carrying has evidence for reducing crying in some studies, and slings make it sustainable.

Responsive feeding.

Movement and rhythmic motion.

White noise and shushing.

Swaddling, done safely and stopped at signs of rolling.

Side or stomach position while held and awake, never for sleep.

Probiotic Lactobacillus reuteri has trial evidence for reducing crying in breastfed infants with colic, with results in formula-fed infants less consistent.

In formula-fed babies with suspected cow's milk protein allergy, a trial of a hydrolysed formula under medical guidance.

And for breastfeeding mothers, a supervised trial of maternal dairy exclusion where allergy is suspected, which should be done with dietetic input rather than indefinitely.

What does not have evidence

Simeticone drops, which have repeatedly failed to outperform placebo.

Gripe water, which varies in composition and lacks evidence.

Lactase drops, except in specific circumstances.

Routine switching between formula brands, which is common and rarely helps.

Manipulative therapies, where reviews find insufficient evidence and where safety concerns exist for spinal manipulation in infants.

Herbal preparations, which are unregulated and occasionally contaminated.

And most of the products marketed specifically for colic.

The safety message

The most important part of this article.

Crying is the most common trigger for abusive head trauma, historically called shaken baby syndrome, which causes devastating and frequently fatal brain injury.

An infant's head is heavy relative to weak neck muscles, and shaking causes brain movement, bleeding and damage.

The critical practical advice: if you feel you might lose control, put the baby down somewhere safe — in their cot, on their back — and walk away.

A baby left crying safely in a cot for a few minutes comes to no harm; a baby shaken for one second may.

Then breathe, call someone, and return when you can.

Everyone who cares for the baby needs to know this, including relatives and any partner, since incidents are frequently caused by someone under stress who was left alone with a crying infant.

Looking after yourself

Not optional in this period.

Take turns where there are two of you, in defined shifts.

Accept and ask for specific help.

Use earplugs or noise-reducing headphones while holding the baby if the sound is unbearable, which is a legitimate strategy.

Get outside daily.

Tell your health visitor or clinician how much you are struggling, honestly, since support exists and is not offered to people who appear to be coping.

And know that finding this period unbearable is common and says nothing about you as a parent.

General information only, not medical advice. Never shake a baby — if you feel overwhelmed, put the baby down safely and get help. Consult a clinician about persistent excessive crying.