How to Tell If You Have a Concussion

A concussion is a form of traumatic brain injury (TBI) that occurs after a blow or jolt to the head. This sudden movement of the head can cause the brain to bounce around or twist in the skull, creating chemical changes in your brain. A concussion typically involves a short loss of brain function.

It may be difficult to determine whether you have a concussion because the symptoms can vary from person to person. Signs and symptoms generally appear soon after the injury. However, you may not know how serious the injury is at first, and some symptoms may not be noticed for hours or even days.

Symptoms of a Concussion - Illustration by Michela Buttignol

Verywell / Michela Buttignol

Symptoms of a Concussion

Following a bump, jolt, or blow to the head, you may experience a concussion. Signs of a concussion that may be observed in you by others include:

  • Being unable to recall events that occur before or after the injury
  • Appearing to be stunned or dazed
  • Being unable to recall instructions
  • Appearing confused
  • Displaying clumsy movements
  • Being slow to answer questions
  • Losing consciousness
  • Having mood, personality, or behavioral changes

For the person experiencing the concussion, the above signs may not be obvious. But there are symptoms of a concussion you may experience that others may not pick up on, including:

  • A headache or pressure in the head
  • Balance issues
  • Dizziness
  • Double or blurry vision
  • Nausea and vomiting
  • Issues with remembering things or feeling confused
  • Feeling like you can’t concentrate
  • Feeling "off" or "down"
  • Sluggishness, or having a hazy, foggy, or groggy feeling in your head

Post-concussion syndrome describes a set of complex symptoms that includes headache, dizziness, neuropsychiatric symptoms, and cognitive impairment occurring after TBI.

Signs in Young Children

When a concussion happens in children or infants, they may have a difficult time communicating the symptoms they are experiencing. Because of this, parents should be aware of signs that their baby or toddler may have a concussion.

The signs that your child has a concussion can include:

  • Crying
  • Complaining of head pain
  • Being unable to sleep, or waking at night
  • Having mood changes, such as uncontrollable laughter or crying or an increased temper
  • Being irritable
  • Vomiting
  • Having noticeable issues with concentration
  • Having balance problems
  • Being more sensitive to light or sound

If you are present when your child hits their head, you should immediately check for signs of concussion. Symptoms may not appear right away, so you should monitor your child for up to 48 hours afterward. If symptoms come on during that time, the child needs to be evaluated by a physician immediately. Check on your child every one to two hours if they have a concussion.


A complication that could occur following a concussion is second-impact syndrome. It arises if a second concussion occurs before the first one fully heals.

Second-impact syndrome can lead to fatal brain swelling. The risk of this complication is much higher in those who play sports, such as football or boxing. This is why it’s vital to always fully recover from a concussion prior to returning to normal activities.

Other complications that can arise following a concussion include:

  • Headaches
  • Vertigo (a feeling of spinning and dizziness)
  • Post-traumatic epilepsy (a seizure disorder)
  • Depression, anxiety, or behavioral changes
  • A specific type of brain degeneration known as chronic traumatic encephalopathy (CTE)

When to See a Doctor

If you have any of the typical signs and symptoms such as confusion, memory issues, nausea or vomiting, and dizziness after hitting your head, you should go to the hospital immediately.

Other symptoms that should prompt you to seek immediate medical attention include trouble using your arms or legs and excessive and worsening sleepiness.

Concussions Doctor Discussion Guide

Doctor Discussion Guide Man


A concussion can occur after a blow to your head or other trauma. The signs observed by others and the symptoms experienced by the person with the concussion may be different. You may notice symptoms immediately following the injury or a few hours or even days afterward.

If you suspect you or someone you're with, including a child, has a concussion, monitor for any changes in mood, vision, and cognitive function and seek help.

A Word From Verywell

Hitting your head or falling can be scary. Sometimes it causes no injuries other than a bump or bruise. At other times, it can be very serious. It’s always best to get any head injury looked at by a healthcare provider.

A concussion is a serious condition that needs to be addressed as soon as possible. Knowing the signs and symptoms of a concussion in yourself or a loved one will help you seek prompt treatment. Getting adequate treatment soon after a concussion reduces the risk of complications and helps prevent prolonged symptoms.

Yes. Although concussions are typically caused by a blow or bump to the head, they can also be caused by a fall or blow to the body that causes the head to jolt back and forth. If the force of the jolt is powerful enough, it can lead to a concussion.

Frequently Asked Questions

  • Do your pupils dilate if you have a concussion?

    Sometimes. Although pupil dilation isn’t always a reliable sign of a concussion, it can occur in some people. Pupil dilation following a concussion typically only occurs in one pupil, with that pupil appearing larger than the other. It could be a sign that the structure of the brain was damaged, and you should go to the emergency department immediately.

  • Are there tests to tell you if you have a concussion?

    Yes. A concussion will typically be diagnosed using a physical exam, which involves testing vision, hearing, balance, coordination, reflexes, memory, and concentration. Other tests may need to be conducted, including an MRI (magnetic resonance imaging) or a CT scan (computed tomography scan) to check for changes in the brain.

    The Food and Drug Administration (FDA) recently approved a test called the Banyan BTI (Brain Trauma Indicator), a blood test designed for adults to measure levels of two protein biomarkers released from the brain into the bloodstream within 12 hours of the injury.

  • How long after a head injury can concussion symptoms start? 

    Concussion symptoms can begin immediately following a head injury, but they can also develop over the course of a few hours or even a few days.

  • Can you get a concussion without hitting your head?

    Yes. Although concussions are typically caused by a blow or bump to the head, they can also be caused by a fall or blow to the body that causes the head to jolt back and forth. If the force of the jolt is powerful enough, it can lead to a concussion.

11 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Angelica Bottaro
Angelica Bottaro is a professional freelance writer with over 5 years of experience. She has been educated in both psychology and journalism, and her dual education has given her the research and writing skills needed to deliver sound and engaging content in the health space.