How Can You Tell If a Baby Has a Concussion?

Babies cannot describe headaches or dizziness, so spotting a concussion in an infant depends almost entirely on behavioral and physical changes you can observe. The most reliable early signs are unusual irritability, excessive drowsiness or difficulty waking, vomiting (especially repeated vomiting), and a visible bump or swelling on the scalp. Emergency physicians who specialize in pediatric head injuries describe diagnosing concussion in young children as one of their toughest challenges, largely because of the child’s age, lack of verbal skills, and the unreliability of standard neurological exams in this age group.¹

The Signs You Can Actually Observe

A toddler or older child with a concussion might tell you their head hurts or that they feel “foggy.” A baby gives you none of that. Instead, you’re watching for changes from how the baby normally acts. A large study tracking concussion symptoms in young children found that irritability was the single most commonly reported symptom across the first month after injury, appearing in roughly three-quarters of cases. Comfort-seeking behavior, where the baby clings to a caregiver and is difficult to console, was nearly as common in the first days.²

Physical symptoms showed a distinct pattern in the same research. Headache and fatigue topped the list in the emergency department, but since a baby cannot report a headache, you’re looking for indirect clues: rubbing or holding the head, squinting, turning away from light, or crying that intensifies when you move them. Sleep disturbances became the most persistent physical symptom over the following weeks and months, with more than half of concussed young children still having disrupted sleep at three months.²

Attention problems were the most frequently endorsed cognitive symptom at every time point studied, from the emergency room visit through the three-month mark.² In a baby, this might look like an unusual inability to focus on a toy, track your face, or engage with stimuli that normally hold their interest. Anxiety emerged as one of the top behavioral symptoms at one and three months post-injury, which in babies may present as heightened startle responses, fussiness in new environments, or resistance to being put down.

When a Bump on the Head Needs Emergency Attention

Not every bump warrants a trip to the emergency room, but some do. The key red flags to watch for immediately after a head impact include:

Loss of consciousness: even a brief moment of going limp or unresponsive.
Seizures: rhythmic jerking of the limbs or sudden stiffness and staring.
Repeated vomiting: a single vomit from crying is common after a scare, but vomiting more than once is a warning sign.
A large or firm scalp swelling: especially one that is not on the forehead. Bumps on the sides or back of the head carry more concern.
Abnormal behavior lasting more than a few minutes: inconsolable crying, unusual drowsiness, or seeming “out of it.”
A bulging fontanelle: the soft spot on top of the head feeling tense or puffed out when the baby is calm and upright.

Doctors who evaluate infant head injuries use a clinical scoring tool that accounts for the size, location, and firmness of scalp bumps. A validated scoring system for infants under one year found that the characteristics of a scalp hematoma, combined with the child’s age and how the injury happened, could reliably identify which infants needed a CT scan and which could safely be observed.³ The scoring system caught all cases of clinically important brain injury at its recommended cutoff point, with no missed cases requiring medical intervention.

How Doctors Evaluate a Baby’s Brain After a Hit

The standard consciousness assessment tool used in adult medicine doesn’t work for babies because it expects the patient to speak, follow verbal commands, and open their eyes on request. A pediatric version was developed specifically to account for the fact that normal verbal and motor responses change with age during the first few years of life.⁴ This modified scale looks at whether a baby coos or babbles appropriately, moves all four limbs spontaneously, and tracks faces or objects with their eyes.⁵

The most widely used decision-making framework for pediatric head injuries is the PECARN rule, which helps emergency physicians decide which children need a CT scan. For children under two, the rule considers factors like the mechanism of injury, how the child is acting, whether they lost consciousness, and the presence and location of scalp swelling. An evaluation of this rule in very young infants, under three months, confirmed that it accurately identified low-risk babies who did not need imaging, with a sensitivity and negative predictive value of 100% for clinically important brain injury.⁶

The decision about whether to order a CT scan is not straightforward. A head CT delivers ionizing radiation, and in young children, this exposure carries a small but real risk of contributing to cancer later in life. A clinical analysis of pediatric head trauma found that the risk of missing a significant brain injury must be weighed against the radiation risk from the scan itself.⁷ This is why doctors don’t scan every baby who bumps their head. The PECARN rule and clinical scoring tools exist precisely to avoid unnecessary scans while catching the injuries that matter.

Common Scenarios That Lead to Baby Head Injuries

Most infant head injuries happen from falls, and the circumstances are painfully ordinary. Falling off a bed, a couch, or a changing table accounts for the majority of cases. A systematic review of injuries from falling out of bed in infants under one year found that while most cases result in mild outcomes, skull fractures and bleeding inside the skull do occur.⁸ One study included in the review found significant injuries in about one in ten infants who presented to the emergency department after a bed fall.

Changing-table falls deserve special mention. A study of South Korean emergency department data found that falls during diaper changes carried a higher proportion of brain injury compared to other types of falls in young children. Nearly half of diaper-change-related falls resulted in a traumatic brain injury diagnosis, and these falls were independently associated with higher odds of skull fracture.⁹ The likely explanation is the height of changing tables combined with the hard surfaces babies land on, and the fact that infants are often unrestrained during the change.

Even short falls can occasionally cause serious injury. A study documenting twelve young children with major closed head injuries from short falls found that seven developed large epidural hemorrhages requiring intervention.¹⁰ These were unusual circumstances, not the norm, but they underscore why even a fall from what seems like a low height shouldn’t be dismissed if the baby is acting abnormally afterward. The overall rate of skull fracture from typical household falls in young children sits around two to three percent, and bleeding inside the skull occurs in about one percent of those fractures.¹¹

Why Infant Skulls Respond Differently to Impact

A baby’s skull is not a miniature adult skull. It is thinner, more flexible, and joined by sutures that have not yet fused. Research measuring the mechanical properties of skull bones in one- to two-year-olds found that suture tissue is significantly more flexible and weaker than the surrounding bone plates.¹² The frontal bone was stiffer and stronger than the parietal bone, and both were much stiffer than the suture material joining them.

This flexibility is a double-edged sword. On one hand, the skull can deform and absorb some impact energy rather than fracturing cleanly. On the other, the brain inside sits in a much larger relative space than in an adult, with more room to move and bounce against the inner walls of the skull during an impact. A baby’s head is also proportionally larger and heavier compared to their body, and their neck muscles are weak, meaning their head decelerates more slowly and with less muscular braking than an older child’s would. All of this makes the infant brain more susceptible to shearing forces from rotational movement even from impacts that seem minor.

What to Watch for at Home After a Head Bump

If your baby has bumped their head and you’ve either been cleared by a doctor or the injury seemed very minor, the next 24 to 48 hours are the critical observation window. You do not need to keep your baby awake all night, which is an outdated piece of advice. You should, however, check on them periodically during sleep, making sure they’re breathing normally and can be briefly roused. Signs that warrant a return trip to the emergency room include worsening irritability, new vomiting, unusual lethargy, or any of the red flags listed earlier.

One challenge that hospitals themselves recognize is the inconsistency of the discharge instructions parents receive. A quality improvement project found that diagnostic labeling and take-home guidance for mild traumatic brain injury varies widely in pediatric emergency departments, and that this inconsistency can increase parental anxiety and lead to unnecessary return visits.¹³ If the instructions you receive feel vague, it’s perfectly reasonable to ask the doctor to spell out exactly what should send you back.

Telemedicine follow-up is emerging as a practical option for monitoring young children after concussion. A study that used video calls to follow up with children after brain injury found that the approach was feasible, though a small number of children did require readmission after worsening symptoms were caught during a scheduled video visit.¹⁴ Having a follow-up plan, whether in person or virtual, is more important than the format.

Recovery and Returning to Normal Activity

The old advice of strict rest in a dark room for days or weeks has been replaced. Current pediatric concussion protocols recommend a brief rest period of 24 to 48 hours, followed by a gradual return to normal activity guided by symptoms.¹⁵ For a baby, “activity” doesn’t mean sports. It means floor time, tummy time, being held and carried, gentle play, and outings. If these activities seem to make the baby fussier or more lethargic, you pull back. If the baby tolerates them normally, you continue.

Updated pediatric protocols specifically shortened the recommended rest period and introduced symptom tiers so that children who recover quickly can progress faster, rather than being held back by a rigid timeline.¹⁶ The key principle is that children should be allowed to progress through recovery stages before they’re completely symptom-free, as long as symptoms are improving and don’t worsen with activity. Prolonged strict rest can actually slow recovery by contributing to deconditioning, mood changes, and social isolation, even in babies who miss out on normal stimulation.

Long-Term Effects Worth Knowing About

Most babies who sustain a mild concussion recover fully within weeks. But the research on longer-term outcomes is worth understanding, especially because the effects can be subtle. A study following children who had experienced mild traumatic brain injury found that, compared to matched peers, they showed more inattentiveness and hyperactive impulsivity on behavioral measures, and performed worse on tasks requiring information processing speed and visual working memory. Their school performance, specifically in technical reading, was measurably lower for up to two years after injury.¹⁷

These are group-level findings, and the effect sizes were in the small-to-medium range. Many individual children showed no measurable deficits at all. But the pattern suggests that even a “mild” brain injury in early childhood is worth tracking developmentally, particularly around attention and reading. If your child seems to be having more difficulty focusing than peers, or if early literacy skills are developing slowly, it’s worth mentioning the head injury history to your pediatrician or a developmental specialist. The injury may not be the cause, but it’s a relevant piece of the puzzle.

When Doctors Worry About Non-Accidental Injury

This is a topic most parents never want to think about, but it’s important to understand because it shapes how emergency physicians approach infant head injuries. When a baby presents with a head injury, doctors are trained to consider whether the mechanism described by the caregiver is consistent with the injury pattern they see. Certain findings raise concern for abusive head trauma.

Research comparing abusive and accidental brain injury in children found distinct patterns. Subdural hemorrhages were present in the vast majority of abusive cases compared to about three-quarters of accidental cases. Seizures and apnea (pauses in breathing) were also more common in abusive injury.¹⁸ A technical report from the American Academy of Pediatrics noted that retinal hemorrhages, or bleeding in the back of the eye, were found in a very high proportion of abusive head trauma cases but in fewer than one in ten accidental cases.¹⁹

If your baby is being evaluated for a head injury in the emergency room and you notice the medical team ordering an eye exam, additional imaging, or a skeletal survey, these are standard-of-care steps for certain injury patterns. They are not an accusation. Physicians are legally and ethically obligated to evaluate for non-accidental trauma when the clinical picture warrants it, and doing so protects children who cannot speak for themselves.

Emerging Diagnostic Tools

Diagnosing concussion in babies and young children remains largely a clinical judgment call, which is why researchers are actively looking for objective tools. Two areas show promise, though neither is standard practice yet for infants.

Blood-based biomarkers are being studied as a way to identify brain injury without radiation exposure. A protein called GFAP, which is released when certain brain cells are damaged, showed preliminary promise as a diagnostic tool for identifying children who had sustained a head injury.²⁰ The FDA has approved a blood test using GFAP and another marker (UCH-L1) for adults, but pediatric validation, especially in babies, is still ongoing. The hope is that a simple blood draw could eventually help clinicians decide which infants need a CT scan and which can be observed.

Eye-tracking technology is another avenue being explored. A study comparing concussed and non-concussed children found that twelve different eye-tracking measurements differed significantly between the two groups, and a model built from these measurements could classify concussion with reasonable accuracy.²¹ Eye tracking works because concussion commonly disrupts the brain’s ability to coordinate eye movements smoothly. For older children who can sit still and follow a target on a screen, this is straightforward. For babies, the technology would need significant adaptation, but the principle that the eyes can reveal what the brain cannot articulate is the same one pediatricians already use informally when they watch whether an infant tracks a face or a finger.

1
Pediatric Emergency Care. Pediatric Emergency Medicine Physicians’ Perspectives of Concussion in Young Children
2
PubMed Central. Postconcussive Symptoms After Early Childhood Concussion
3
PubMed Central. The Infant Scalp Score: A Validated Tool to Stratify Risk of Traumatic Brain Injury in Infants With Isolated Scalp Hematoma
4
PubMed. Assessing the conscious level in infants and young children: a paediatric version of the Glasgow Coma Scale
5
PubMed. Head injuries in infants and young children: the value of the Paediatric Coma Scale
6
PubMed. Evaluation of the PECARN rule for traumatic brain injury applied to infants younger than 3 months and creation of a modified, age-specific rule
7
PubMed. Pediatric traumatic brain injury and radiation risks: a clinical decision analysis
8
Injury Prevention. Injuries from falling out of bed in infants under 1 year of age: a systematic review
9
PubMed Central. Traumatic brain injury from diaper change-related falls in children younger than 3 years: an evaluation of South Korean national emergency department registry data
10
Pediatric Emergency Care. Short Falls in Childhood Occasionally Cause Major Brain Injuries Because of Unusual Circumstances
11
PubMed Central. Accidental Traumatic Head Injury in Infants and Young Children
12
PubMed Central. Mechanical Properties of Cranial Bones and Sutures in 1–2-Year-Old Infants
13
Pediatric Emergency Care. Standardization of Discharge Instructions by Age for Children Presenting to the ED With Mild Traumatic Brain Injury: A Quality Improvement Project
14
PubMed Central. Challenges and effectiveness of remote neurological follow-up of children with concussion following TBI using telemedicine
15
British Journal of Sports Medicine. Rest and treatment/rehabilitation following sport-related concussion: a systematic review
16
PubMed. Concussion Management for Children Has Changed: New Pediatric Protocols Using the Latest Evidence
17
PubMed. Long-Term Neurodevelopmental Outcome of Children With Mild Traumatic Brain Injury
18
PubMed Central. Severe Pediatric Traumatic Brain Injury Presenting Characteristics: Abusive Versus Accidental Trauma
19
Pediatrics. Abusive Head Trauma in Infants and Children: Technical Report
20
PubMed Central. Are UCH-L1 and GFAP promising biomarkers for children with mild traumatic brain injury?
21
PubMed Central. Eye Tracking as a Biomarker for Concussion in Children