Urgent & emergency

Head Injury: Warning Signs That Mean Go to the ER Now

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Go to the ER after a head injury if the person is unconscious, confused, vomiting repeatedly, having a seizure, has unequal pupils, or cannot walk or speak normally. People taking blood thinners and adults over 65 need emergency evaluation even after a minor blow. A CT scan is the standard test to detect bleeding the symptoms alone cannot rule out.

Last updated: July 2026History

If this is happening now

Call 911 if the person is unconscious, seizing, or cannot be woken. Go to the ER immediately for any red flag above. For mild symptoms with no red flags, urgent care or a primary care visit within 24 hours is appropriate — but monitor closely at home and go to the ER if any new symptoms develop.

Care like this may require 911 or emergency services. Gale doesn't schedule appointments for emergencies — emergency care comes first; scheduled follow-up can wait until you're safe.

Signs that mean go to the ER immediately

Go immediately — do not wait to see if symptoms improve — if any of these are present after a head injury:

  • Loss of consciousness, even briefly
  • Confusion, disorientation, or unusual behavior
  • Cannot remember the injury or events around it
  • Repeated vomiting (more than once or twice)
  • Seizure after the injury
  • One pupil larger than the other
  • Severe or worsening headache
  • Slurred speech, difficulty finding words
  • Weakness or numbness in an arm or leg
  • Difficulty walking or balance problems
  • Visible skull deformity, deep laceration, or heavy bleeding
  • Clear fluid draining from the nose or ears
  • In infants: will not wake, won’t stop crying, or has a bulging fontanelle (soft spot) 12

What is a concussion — and why does it need evaluation?

A concussion is a brain injury caused by the head being shaken or struck. It does not require a loss of consciousness — someone can be concussed and walk away or seem fine for an hour before symptoms develop. The CDC’s HEADS UP program 1 identifies four symptom domains: physical (headache, dizziness, nausea, sensitivity to light or noise), cognitive (fogginess, difficulty concentrating, memory gaps), emotional (irritability, anxiety, sadness), and sleep (sleeping more or less than usual, insomnia).

Concussions are real brain injuries. Most resolve with rest, but some people — especially those who return to activity too soon or have had prior concussions — take longer to recover or develop lasting problems. Any suspected concussion deserves a clinician’s evaluation.

Who needs extra caution after a head injury

People on blood thinners: Anticoagulant medications — warfarin, apixaban, rivaroxaban, dabigatran — and higher-dose aspirin prevent clotting and raise the risk of bleeding in and around the brain after even a modest impact. Any head injury in this group warrants emergency evaluation.

Adults over 65: The brain changes with age, leaving more room where blood can accumulate before pressure becomes obvious. Older adults can develop slow bleeds — subdural hematomas — that cause subtle symptoms days to weeks after an injury.

Infants under 1 year: Infants cannot describe symptoms. Any significant head injury in an infant warrants emergency evaluation — do not wait for obvious symptoms to appear 2.

Anyone with prior concussions: A history of head injuries can increase recovery time and, in some situations, raise the risk of complications with subsequent impacts.

After a minor bump: what to watch for at home

If none of the emergency signs above are present after a minor bump to the head, careful home observation for 24 hours is appropriate. The American Academy of Pediatrics 2 recommends checking the child every 2–3 hours to confirm normal movement, responsiveness, and recognition. Watch for:

  • Worsening headache
  • New vomiting
  • Increasing confusion or unusual behavior
  • Difficulty waking up or staying awake
  • New weakness, numbness, or coordination problems
  • A seizure

If any of these develop, go to the ER immediately — do not wait until morning.

What a clinician will do

A clinician will ask how the injury happened, whether consciousness was lost and for how long, what symptoms have appeared, and whether blood thinners are involved. CT scan is the first-line imaging modality in the ER for suspected intracranial injury — it can rapidly detect bleeding, fractures, and swelling 3. Clinical decision rules (such as the NEXUS Head criteria or Canadian CT Head Rule) help guide selective CT use in mild head trauma, avoiding unnecessary radiation while ensuring serious injuries are not missed. For concussion without red flags, standardized assessment tools help grade symptom severity and guide return-to-activity decisions.

Common questions

Yes. A concussion does not require loss of consciousness. Someone can feel fine immediately after a head impact and develop symptoms — headache, fogginess, nausea — minutes to hours later. If any of the red flag symptoms appear after a head injury, go to the ER regardless of whether consciousness was lost.

For most minor bumps with no red flag symptoms, sleep is safe. The old advice to keep someone awake all night is not current guidance. However, it is reasonable to check on the person periodically to make sure they can be roused and are not confused. If they become very difficult to wake or develop new symptoms, go to the ER immediately.

Blood thinners reduce the blood's ability to clot. After a head injury, a small bleed that a healthy person's body would stop can continue to expand in someone on anticoagulants. This can cause pressure on the brain even from an injury that seemed minor. Any head injury in someone on warfarin, apixaban, rivaroxaban, dabigatran, or higher-dose aspirin warrants emergency evaluation.

Return to sport or strenuous activity after a concussion should follow a stepwise protocol guided by a clinician, with each stage completed symptom-free before advancing. Returning too quickly — while still having any symptoms — raises the risk of a second injury before the brain has healed. A sports medicine or primary care clinician can help build this plan.

Related

Call 911 or go to the ER now for any of these

  • —Loss of consciousness, even briefly
  • —Cannot be woken up or is very difficult to rouse
  • —Repeated vomiting after the injury
  • —Seizure
  • —Unequal pupils
  • —Severe headache or headache that is rapidly worsening
  • —Slurred speech, confusion, or inability to recognize people or places
  • —Weakness, numbness, or trouble walking
  • —Clear fluid draining from the nose or ears
  • —Visible skull deformity
  • —Infant who will not stop crying or has a bulging soft spot
  • —Person on blood thinners — any head injury

Call 911 if the person is unconscious, seizing, or cannot be woken. Go to the ER immediately for any red flag above. For mild symptoms with no red flags, urgent care or a primary care visit within 24 hours is appropriate — but monitor closely at home and go to the ER if any new symptoms develop.

This article is general health information and not a diagnosis. If you or someone with you has any of the signs above after a head injury, call 911 or go to the emergency room immediately.

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References

  1. 1.Centers for Disease Control and Prevention (2025). Signs and Symptoms of Concussion. CDC HEADS UP Program. link ✓Concussion symptom clusters including headache, fogginess, sensitivity to light, nausea, dizziness, and the danger signs that require emergency care (seizure, unequal pupils, repeated vomiting, loss of consciousness)
  2. 2.American Academy of Pediatrics (2024). Head Injury in Children: How to Know If It's Minor or Serious. HealthyChildren.org. link ✓Pediatric head-injury red flags warranting ER evaluation: loss of consciousness, persistent headache, vomiting more than 2–3 times, difficulty waking, unequal pupils, seizures, and limb weakness; guidance on home observation after minor bump
  3. 3.Expert Panel on Neurological Imaging; Shih RY, Burns J, et al. (2021). ACR Appropriateness Criteria® Head Trauma: 2021 Update. Journal of the American College of Radiology. doi:10.1016/j.jacr.2021.01.006 ✓CT as the first-line imaging modality for suspected intracranial injury; selective CT use in mild head trauma based on clinical decision rules; role of CT in detecting bleeding, fractures, and swelling

3 sources, numbered by first appearance. General health information, not medical advice. AI-assisted editorial content — every citation independently verified. Editorial policy

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