If your child hit their head and you’re unsure whether it’s serious, certain signs mean you should go to the emergency room right away: a seizure, loss of consciousness, repeated vomiting, one pupil larger than the other, or any behavior that seems genuinely “off” compared to normal. Most childhood head bumps don’t cause lasting harm, but the ones that do can worsen quickly, so knowing exactly what to watch for matters.
Signs That Mean Go to the ER Now
The CDC lists these as danger signs after any bump, blow, or jolt to a child’s head:
- Seizures or convulsions (shaking, twitching)
- Loss of consciousness that lasts more than a few seconds, or increasing drowsiness where you can’t wake the child
- Repeated vomiting (one episode of vomiting after a head bump can be normal from crying or stress, but two or more times is a red flag)
- One pupil larger than the other or complaints of double vision
- Slurred speech, weakness, numbness, or poor coordination
- A headache that keeps getting worse and won’t go away
- Inability to recognize familiar people or places
- Unusual behavior, increasing confusion, restlessness, or agitation
Any single one of these is enough to call 911 or drive to the nearest emergency department. You don’t need to see multiple signs before acting.
Babies and Toddlers Under 2
Infants can’t tell you they have a headache or blurry vision, so the warning signs look different. For babies, the two biggest red flags are inconsolable crying that nothing will calm and refusal to nurse or eat. These can signal rising pressure inside the skull even when the baby looks otherwise okay on the outside.
A bulging or tense soft spot (fontanelle) is another serious sign. In one study of infants with bleeding inside the skull after head trauma, a full or bulging fontanelle showed up in about 42% of cases. Pallor, or looking unusually pale, appeared in every single case. If your baby looks pale and won’t stop crying after a head bump, that combination warrants an ER visit.
Where the Bump Is Matters
In children under 2, the location of scalp swelling carries real diagnostic weight. A bump on the forehead is generally the least concerning. Swelling on the side of the head (the temporal or parietal area, roughly above and behind the ear) or the back of the head (the occipital area) is associated with roughly six times higher odds of an underlying brain injury compared to children without swelling. For babies under 6 months old, a scalp bump in any location is especially concerning, with dramatically higher odds of intracranial injury. Larger bumps also carry more risk than small ones.
This doesn’t mean every bump on the side or back of the head is dangerous. It means these locations deserve closer attention, and if you see swelling in these areas along with any behavioral change, an ER evaluation is the right call.
What Doctors Look For
Emergency physicians use a well-validated set of criteria called the PECARN rules to decide which children need brain imaging after a head injury. These rules are split by age because the risk factors differ.
For children younger than 2, the six factors that raise concern are: altered mental status, a scalp bump that isn’t on the forehead, loss of consciousness lasting 5 seconds or more, a severe mechanism of injury (like a fall from several feet or a car accident), a palpable skull fracture, or a parent reporting the child is “not acting normally.”
For children 2 and older, the six factors are: abnormal mental status, any loss of consciousness, vomiting, a severe injury mechanism, signs of a skull base fracture (like bruising behind the ears or blood visible behind the eardrum), or a severe headache.
Notice that “not acting normally per the parent” is an actual clinical criterion for younger children. Your gut feeling that something is wrong has diagnostic value. If your child seems different in a way you can’t quite name, that counts.
Loss of Consciousness: How Long Is Too Long
Any loss of consciousness after a head injury in a child deserves medical evaluation. For children under 2, the threshold used in clinical decision-making is just 5 seconds. For children 2 and older, any loss of consciousness at all is a flag for closer evaluation.
Brief loss of consciousness (under 5 minutes) can happen with a concussion and doesn’t automatically mean there’s bleeding in the brain. But it does mean the injury was significant enough that a doctor should assess your child. If your child was knocked out for more than a few minutes, or if they lost consciousness and then seem confused or sleepy afterward, that’s more urgent.
The 24 to 48 Hour Watch Window
If your child bumps their head but seems fine and doesn’t show any of the red flags above, you still need to monitor them closely for 24 to 48 hours. Some brain injuries develop symptoms gradually as slow bleeding or swelling builds up inside the skull.
During this window, check on your child periodically, including waking them at least once or twice during the night to confirm they respond normally. You’re watching for any of the danger signs listed above, plus a few additional ones: unusual stiffness in the neck, clear fluid leaking from the nose or ear, bleeding from the ear, weakness in an arm or leg, or numbness in the face or limbs.
For the first day or two, limit screen time and mentally demanding activities. This means less homework, less video games, and more rest. A concussed brain recovers faster with reduced stimulation in the early period. Physical rest matters too, so hold off on sports and roughhousing until you’re confident your child is symptom-free.
How the Injury Happened Matters
The mechanism of injury is one of the six criteria doctors use to assess risk. “Severe mechanism” generally means a fall from a height of 3 feet or more for children under 2 (roughly the height of a changing table), a fall from 5 feet or more for older children, a motor vehicle crash, being struck by a high-impact object, or a bicycle accident without a helmet.
A toddler who rolls off a couch onto carpet is in a different risk category than one who falls from a shopping cart onto a hard floor. If the fall or impact was forceful enough that it scared you as a witness, that’s worth mentioning to a doctor, even if the child seems okay at first.
What to Expect at the ER
When you arrive, the medical team will assess your child’s alertness, responsiveness, coordination, and pupils. They’ll ask exactly how the injury happened, whether there was any loss of consciousness, and how the child has been acting since. For babies, they’ll feel the skull and fontanelle and observe how the child responds to parents.
Not every child who comes to the ER for a head injury gets a CT scan. Doctors weigh the clinical criteria against the small radiation risk of scanning a young brain. If your child is alert, acting normally, has no vomiting, and the injury mechanism wasn’t severe, they may recommend a period of observation instead. If any of the higher-risk criteria are present, imaging is typically done promptly. The scan itself takes only a few minutes and gives a clear picture of whether there’s bleeding, swelling, or a fracture.