Quick Summary
Seek emergency medical care immediately after a head injury if any of the following occur:
- Loss of consciousness
- Severe or worsening headache that does not go away
- Repeated vomiting or nausea
- Seizures or convulsions
- Increasing confusion, agitation, or unusual behavior
- Slurred speech or difficulty speaking
- Weakness, numbness, or poor coordination
- One pupil larger than the other or vision problems
- Clear fluid or blood draining from the nose or ears
- Inability to wake up or extreme drowsiness
Symptoms may appear right away or hours to days later, so monitoring after a head injury is important.
Introduction
A head injury can affect the brain in ways that are not always immediately obvious. Symptoms may appear right away or develop hours to days later. Because some signs are associated with serious or life-threatening conditions, recognizing when urgent or emergency medical care is needed is essential. This article summarizes verified medical guidance on warning signs, symptoms, evaluation, recovery, and prevention related to head injuries and concussions.
What Is a Head Injury?
A head injury is an injury that damages the head, including the skull or brain. Head injuries vary in severity and may be classified as mild, moderate, or severe. Even mild injuries require attention, as symptoms may not appear immediately and complications can occur.
A traumatic brain injury (TBI) results from trauma such as a blow, jolt, or penetrating injury that affects the brain. TBIs can cause short-term symptoms or long-term physical, cognitive, or emotional changes.
Why Symptoms May Appear Later
Symptoms of head injury or concussion do not always occur at the time of injury. They may develop hours, days, or even weeks later. Because of this delayed presentation, monitoring for new or worsening symptoms after a head injury is important.
Warning Signs That Require Emergency Care
Seek emergency medical care immediately if any of the following occur after a head injury:
- Loss of consciousness
- A headache that is severe or worsening and does not go away
- Repeated vomiting or nausea
- Seizures or convulsions
- Increasing confusion, agitation, restlessness, or unusual behavior
- Slurred speech or difficulty speaking
- Weakness, numbness, or decreased coordination
- One pupil larger than the other or double vision
- Clear fluid or blood draining from the nose or ears
- Inability to wake up or extreme drowsiness
These signs are associated with serious brain injury and may indicate complications such as bleeding inside the skull.
Symptoms That Need Medical Evaluation
Some symptoms may not require emergency services but still warrant prompt medical evaluation:
- Headache that does not improve
- Dizziness or balance problems
- Persistent nausea
- Memory or concentration difficulties
- Sensitivity to light or sound
- Mood, behavior, or personality changes
If symptoms worsen or new symptoms appear, emergency care is recommended.
Warning Signs in Children
Infants and Toddlers
Seek medical care if an infant or toddler has:
- Persistent crying or inability to be consoled
- Refusal to eat or nurse
- Vomiting after the injury
- Unusual sleepiness or difficulty waking
- Seizures or loss of consciousness
School-Aged Children and Teens
Watch for:
- Headache or dizziness
- Trouble concentrating or remembering
- Changes in mood, behavior, or personality
- Balance problems
- Vision changes
Emergency care is required if any danger signs appear at any age.
Common Symptoms of Concussion
Concussion symptoms commonly fall into these groups:
Physical
- Headache
- Nausea or vomiting
- Dizziness or balance problems
- Fatigue
Cognitive
- Feeling slowed down or “foggy”
- Difficulty concentrating or remembering
Emotional
- Irritability
- Anxiety
- Sadness
Sleep-Related
- Sleeping more or less than usual
- Trouble falling asleep
Symptoms may change during recovery and should be monitored.
Types of Head Injuries
Head injuries are commonly classified as:
- Closed head injuries: The skull is not broken
- Open or penetrating head injuries: An object pierces the skull and enters the brain
- Concussion: A mild form of traumatic brain injury caused by a blow or jolt
- More severe injuries: Including injuries associated with brain bleeding or significant trauma
The type and severity of injury influence treatment and risk.
Common Causes and Higher-Risk Groups
Common causes of head injury include:
- Falls
- Motor vehicle crashes
- Sports and recreational activities
- Physical assaults
Higher-risk groups include young children, older adults, and people who participate in contact sports.
What to Expect During Medical Evaluation
Medical evaluation of a head injury may include:
- A physical examination
- A neurological examination
- Questions about symptoms, timing, and how the injury occurred
Some diagnostic tests are used based on clinical judgment and severity.
Home Care for Minor Head Injury (When Medically Approved)
Do
- Rest and avoid stress or intense physical activity
- Follow medical advice for symptom management
- Ensure another adult stays with the injured person for at least the first 24 hours
Don’t
- Return to work, school, or contact sports until symptoms improve
- Resume intense physical activity too soon
- Ignore worsening symptoms
Return for medical care if symptoms persist or worsen.
Recovery and Possible Complications
Recovery varies depending on the person and severity of injury. Some people recover within days, while others experience symptoms for weeks or longer.
Serious head injuries can lead to complications such as:
- Bleeding inside the skull
- Increased pressure on the brain
- Seizures
- Long-term cognitive or emotional changes
Prevention
Steps that reduce the risk of head injury include:
- Wearing seatbelts and using appropriate child restraints
- Wearing helmets during sports and recreational activities
- Preventing falls, especially in older adults
- Creating safe play environments for children
When to See a Doctor
Seek immediate emergency care for any danger signs listed above. Medical evaluation is also recommended if symptoms are persistent, worsening, or concerning, even if they appear mild at first.
Frequently Asked Questions
When should I go to the ER after hitting my head?
Emergency care is recommended for loss of consciousness, worsening headache, repeated vomiting, seizures, confusion, weakness, or difficulty waking.
What are the warning signs of a serious head injury?
Warning signs include severe or worsening headache, repeated vomiting, seizures, confusion, slurred speech, weakness, unequal pupils, or inability to wake.
How long after a head injury can symptoms start?
Symptoms may appear immediately or develop hours, days, or weeks later.
Is it safe to sleep after a concussion?
There is no high-quality evidence supporting or refuting this in the verified sources. Follow clinician-specific instructions if given.
How can I tell if I have brain damage?
There is no high-quality evidence supporting self-diagnosis. Diagnosis requires medical evaluation.
How long after hitting my head could vomiting occur?
Vomiting can occur after a head injury and is considered a warning sign when repeated.
How long should you wait to fall asleep after a concussion?
There is no high-quality evidence supporting a specific waiting period. Follow medical advice provided during evaluation.
APA References List
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Centers for Disease Control and Prevention. (2025, September 15). Returning to sports. https://www.cdc.gov/heads-up/guidelines/returning-to-sports.html
Centers for Disease Control and Prevention. (2025, September 15). Signs and symptoms of concussion. https://www.cdc.gov/heads-up/signs-symptoms/index.html
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Mayo Clinic Staff. (n.d.). Traumatic brain injury: Symptoms & causes. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/traumatic-brain-injury/symptoms-causes/syc-20378557
Mayo Clinic Staff. (2024, January 12). Concussion: Symptoms & causes. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/concussion/symptoms-causes/syc-20355594
National Health Service. (n.d.). Head injury and concussion. NHS. https://www.nhs.uk/conditions/head-injury-and-concussion/
National Institute of Neurological Disorders and Stroke. (2025, July 21). Traumatic brain injury (TBI). https://www.ninds.nih.gov/health-information/disorders/traumatic-brain-injury-tbi
National Institute for Health and Care Excellence. (2023, May 18). Head injury: Assessment and early management (NICE guideline NG232): Recommendations. https://www.nice.org.uk/guidance/ng232/chapter/recommendations