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

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) 1Ref 1Centers for Disease Control and Prevention (2025).Signs and Symptoms of Concussion.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)2Ref 2American Academy of Pediatrics (2024).Head Injury in Children: How to Know If It's Minor or Serious.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

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 1Ref 1Centers for Disease Control and Prevention (2025).Signs and Symptoms of Concussion.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) 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 2Ref 2American Academy of Pediatrics (2024).Head Injury in Children: How to Know If It's Minor or Serious.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.

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 2Ref 2American Academy of Pediatrics (2024).Head Injury in Children: How to Know If It's Minor or Serious.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 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 3Ref 3Expert Panel on Neurological Imaging; Shih RY, Burns J, et al. (2021).ACR Appropriateness Criteria® Head Trauma: 2021 Update.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. 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.