Why Does My Baby Cry Every Evening? Understanding PURPLE Crying & Colic

Quick answer: This pediatrician-reviewed guide to purple crying gives you the exact evidence-based steps parents ask about — what is normal, what to try at home, and when to call the doctor.

Key facts about purple crying every parent should know

Below is the short, evidence-based summary on purple crying before you read the full guide. Skim these first — they cover 90% of the questions parents actually ask.

Written by Dr. S. Xishan, MD, FAAP — Board-Certified Pediatrician & Neonatologist (Weill Cornell/NYP). Medically reviewed July 2026.

It starts like clockwork. Every evening, usually between 6 PM and midnight, your baby begins to cry. Not the ‘I need a diaper change’ cry. Not the ‘I am hungry’ cry. This is a different kind of crying — intense, inconsolable, and seemingly unrelated to anything you can identify or fix.

You have fed them. You have changed them. You have rocked them, swayed them, shushed them, offered the pacifier, tried the swing, walked the halls. Nothing works. The crying goes on for an hour. Two hours. Sometimes longer. And then, as suddenly as it started, it stops.

If this sounds familiar, you are experiencing one of the most universal — and most poorly understood — phenomena in infant development. The most accurate framework for understanding it is the PURPLE crying model, developed by pediatric researchers to help parents understand what is actually happening — and to prevent the most dangerous consequence of inconsolable crying: shaken baby syndrome.

Part 1: The PURPLE Curve — What Normal Crying Looks Like

1.1 The Data on Infant Crying

Researchers who have studied infant crying across cultures have documented a consistent pattern: crying increases in the first 2-3 weeks, peaks at approximately 6-8 weeks, and gradually decreases by 3-4 months. This curve is consistent across cultures, feeding methods, and parenting styles. It appears to be a neurodevelopmental phenomenon — a phase of the baby’s nervous system development that manifests as increased crying.

1.2 The PURPLE Crying Framework

• P — Peak pattern: Crying peaks at 2 months and then gradually declines.
• U — Unexpected: Crying bouts can come and go without an apparent reason.
• R — Resists soothing: The baby may not be soothed by any method.
• P — Pain-like face: The baby may look as though they are in pain, even when they are not.
• L — Long bouts: Crying can last for 2-3 hours or more.
• E — Evening clustering: Crying tends to cluster in the late afternoon through midnight.

The key insight: this pattern is NORMAL. It does not mean the baby is sick, in pain, or poorly cared for.

1.3 Colic: A Definition, Not a Diagnosis

The traditional ‘Rule of Threes’ (crying more than 3 hours a day, more than 3 days a week, for more than 3 weeks) is increasingly considered outdated because it pathologizes what is actually a normal developmental phase. Most babies who meet the rule are healthy, growing normally, and simply going through the PURPLE period.

Part 2: When Evening Crying Is NOT PURPLE Crying — Conditions to Rule Out

2.1 Gastroesophageal Reflux (GER/GERD)

Signs suggesting reflux: back-arching during or after feeds, frequent spit-up or vomiting, crying during or immediately after feeds, refusal to feed, poor weight gain, coughing or respiratory symptoms, worse when lying flat.

2.2 Cow’s Milk Protein Allergy (CMPA)

Signs: blood or mucus in the stool, eczema, excessive gas, vomiting, symptoms that improve when the mother eliminates dairy or the baby is switched to a hypoallergenic formula. CMPA affects approximately 2-3% of infants.

2.3 Hair Tourniquet

A rare but easily missed cause: a hair or thread wrapped tightly around a toe, finger, or penis. Remove all socks and mittens and examine each digit carefully.

2.4 Corneal Abrasion

A scratched cornea can cause intense crying and eye tearing. If one eye appears red, teary, or sensitive to light, have the eye examined.

2.5 Otitis Media (Ear Infection)

Signs: fever, pulling at the ear, crying when lying down, recent upper respiratory infection.

2.6 Intussusception (Rare but Serious)

Sudden onset of intense, episodic crying (baby draws legs up, screams, then appears normal between episodes), vomiting that may become bilious, ‘currant jelly’ stool, lethargy. This is a medical emergency. Go to the ER immediately.

Part 3: What Actually Helps — Evidence-Based Soothing

3.1 The 5 S’s (Dr. Harvey Karp’s Framework)

1. Swaddling: Snug wrapping reduces the startle reflex.
2. Side/Stomach position: Hold on side or stomach (only while awake and supervised — always back to sleep).
3. Shushing: Loud, continuous white noise near the baby’s ear.
4. Swinging: Small, rapid, rhythmic micro-movements — not large sweeping motions.
5. Sucking: Non-nutritive sucking via pacifier or clean finger.

These techniques are most effective when combined, not individually.

3.2 The ‘Football Hold’ (Colic Carry)

Hold the baby face-down along your forearm, head near your elbow, legs straddling your hand. Gentle pressure on the abdomen can help gassy babies.

3.3 Change the Environment

Go outside, drive or walk, or reduce sensory stimulation (dim lights, quiet room).

3.4 Check Your Own State — And Know When to Step Away

Babies are exquisitely attuned to their caregivers. If you feel yourself reaching the breaking point: put the baby in a safe place (crib), walk to another room, close the door, and take 5-10 minutes to breathe. The baby will be safe. This is infinitely safer than the alternative.

Shaken Baby Syndrome is the most dangerous consequence of PURPLE crying. Shaking a baby — even for a few seconds — can cause permanent brain damage or death. If you ever feel like you might shake your baby, put them down and step away. Call the National Shaken Baby Syndrome prevention hotline (1-888-538-7223 in the US). There is no shame in needing support.

Part 4: What Does NOT Help (Despite Popular Claims)

• Gripe water: No high-quality evidence supports its efficacy.
• Gas drops (simethicone): No more effective than placebo in studies.
• Herbal teas: Limited evidence, allergen risk, no standardized dosing.
• Frequent formula changes: Can worsen digestive upset unless CMPA is diagnosed.
• Rice cereal in the bottle: Not appropriate before 4-6 months. Choking and aspiration risk.
• Probiotics (L. reuteri): Some evidence in breastfed infants; discuss with your pediatrician.

Pediatrician’s Take

The most important thing I want parents to understand about evening crying in the first 3 months is that it is almost always normal. The PURPLE crying curve — peaking at 6-8 weeks and resolving by 3-4 months — is a neurodevelopmental phenomenon, not a disease. Your baby is not in pain despite the pain-like facial expression. The most important strategy is to ensure you have support and a plan for when the crying feels unbearable. Put the baby in a safe place and step away if you need to. That is not failure — that is the safest, most responsible thing you can do.

When to Call the Doctor

• Fever of 100.4°F (38°C) or higher in a baby under 3 months is always an emergency.
• Forceful/projectile vomiting or vomiting green/yellow bile.
• Blood or mucus in the stool.
• Poor weight gain or lethargy.
• Episodic screaming with legs drawn up (possible intussusception).
• Suspected hair tourniquet, corneal abrasion, or ear infection.
• You feel like you might harm yourself or the baby — call for help immediately.

Medical disclaimer: This article is for informational purposes only and does not constitute medical advice. If your baby’s crying is severe, persistent, or accompanied by other symptoms, consult your pediatrician.

Frequently Asked Questions

Related: When Do Babies Sleep Through the Night? A Realistic Age-by-Age Guide

Related: Best Video Baby Monitors for Peace of Mind: Pediatrician-Reviewed Picks for Security, Clarity & Reliability

Reference: World Health Organization – Maternal & Child Health

Related Resources

Explore more pediatrician-reviewed guidance from ChildBloom:

• The Pediatrician’s Complete Nursery Setup Guide: Safe Sleep, Air Quality & Essentials
• Nursery Temperature: The Ideal Range for Safe Sleep & Comfort
• Do You Need a Nursery Glider? Ergonomics for Feeding & Back Health
• Best Nursery Lighting for Baby’s Circadian Rhythm

Authoritative External Sources

• American Academy of Pediatrics
• HealthyChildren.org (AAP)

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