Written by Rose Kivi and Elea Carey | Published on September 26, 2015
Medically Reviewed by George Krucik, MD, MBA on September 26, 2015

What Is a Concussion?

A concussion is a mild traumatic brain injury (TBI). It can occur after an impact to the head or after a whiplash-type injury that causes the head and brain to shake quickly back and forth. Concussions are usually not life-threatening, but they can cause serious symptoms that require medical treatment. A concussion is a traumatic injury that results in an altered mental state that may include becoming unconscious.

Anyone can become injured during a fall, car accident, or any other daily activity. If you participate in impact sports such as football or boxing, you have an increased risk of getting a concussion.

The Centers for Disease Control and Prevention (CDC) estimate that in 2010 approximately 2.5 million people in the United States visited the hospital with TBIs.

Recognizing the Signs and Symptoms of a Concussion

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Symptoms of a concussion vary depending on both the severity of the injury and the person injured. It’s not true that a loss of consciousness always occurs with a concussion. Some people do experience a loss of consciousness, but others do not.

The symptoms may begin immediately, or they may not develop for hours, days, weeks, or even months following the injury. The signs of a concussion may include:

  • brief loss of consciousness after the injury
  • memory problems
  • confusion
  • drowsiness or feeling sluggish
  • dizziness
  • double vision or blurred vision
  • headache
  • nausea or vomiting
  • sensitivity to light or noise
  • balance problems
  • slowed reaction to stimuli

During the recovery period after a concussion, you may experience the following symptoms:

  • irritability
  • sensitivity to light or noise
  • difficulty concentrating
  • mild headaches

You Asked, We Answered

  • I've always heard that you should keep someone awake for 24 hours if they've suffered a significant head injury, but is that true? Why is it so important?- Anonymous
  • The traditional teaching is that it is important to awaken someone periodically after a traumatic brain injury (e.g., if they have suffered loss of consciousness or a severe concussion) in order to be certain that they are not deteriorating. Being unable to arouse someone would be indicative of an extreme situation. But the act of sleeping itself would not be harmful. In the hospital, if someone has suffered a sufficiently bad injury, it is likely that they would have had a CT scan or MRI to directly identify an area of bleeding, fractured skull, or other injury. In the wilderness, away from testing, it is reasonable to awaken someone every few hours to be certain that they are not getting worse. There is no absolute interval for or duration of such evaluation, but remember that at some point, people need to sleep because they are tired, and rest is important for recovery.

    - Paul Auerbach, MD, MS, FACEP, FAWM

Emergency Symptoms: When to See a Doctor

when to see a doctor

See a doctor if you suspect that you or someone else has a concussion. If a concussion occurs during sports practice or a game, tell the athletic coach and go to a doctor. If you, or someone you know, experiences any of the following severe symptoms after an injury, seek immediate emergency medical treatment or call 911:

  • an inability to wake up (also called a coma)
  • seizures
  • draining of blood or clear fluid from the ears or nose
  • unequal pupil size (one pupil is larger than the other)
  • abnormal eye movement
  • lasting confusion
  • slurred speech
  • repeated vomiting
  • weak muscles
  • problems walking

Concussions may be accompanied by injuries to the spine. If you suspect that the person has a neck or back injury, avoid moving them and call an ambulance for help. If you absolutely must move the person, do so very carefully. You should try to move the person’s neck and back as little as possible. This will avoid causing further damage to the spine.

How Is a Concussion Diagnosed?

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If a doctor or emergency room visit is necessary, your doctor will begin with questions about how the injury happened and its symptoms. Your doctor might then perform a physical examination to determine what symptoms there are.

In the case of serious symptoms, your doctor may request a magnetic resonance imaging (MRI) scan or a computerized tomography (CT) scan of the brain to check for serious injuries. In the case of seizures, your doctor may also perform an electroencephalogram (EEG) test, which monitors brain waves.

How Is a Concussion Treated?

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Treatment for a concussion depends on the severity of your symptoms. You might need surgery or other medical procedures if you have bleeding in the brain, swelling of the brain, or a serious injury to the brain. However, most concussions do not require surgery or any major medical treatment.

During the first 24 hours after the injury, your doctor may ask that someone wake you every two to three hours. This ensures that you haven’t gone into a coma and also allows someone to check for signs of severe confusion or abnormal behavior.

If the concussion is causing headaches, your doctor may recommend over-the-counter pain relievers such as ibuprofen (Advil) or acetaminophen (Tylenol). Your doctor will also probably ask you to get plenty of rest, avoid sports and other strenuous activities, and avoid driving a vehicle or riding a bike for 24 hours or even few months, depending on the severity of your injury. Alcohol might slow recovery, so ask your doctor if you should avoid drinking it. If you should avoid alcohol, ask your doctor for how long.

A Warning Regarding the Long-Term Effects of Multiple Concussions


Anyone who has had a concussion should not return to sports or strenuous activities without a doctor’s permission. Getting a second concussion before the first concussion is healed can cause a condition known as second impact syndrome (SIS), which can increase the chances of severe brain swelling and may be fatal.

Remember, it’s important to take time to rest after any concussion. This allows the brain to heal. Even once your doctor has granted permission to return to sports or exercise, that return should be gradual.

How to Prevent Concussions

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You can reduce your risk of getting a concussion by wearing the correct helmet and other athletic safety gear during sports activities. Always make sure the helmet and other gear fit properly and are worn appropriately. Ask a coach or other sports professional about safe playing techniques, and make sure to follow their advice. The CDC provides an extensive overview of concussion information.

Long-Term Outlook After a Concussion

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Most people completely recover from their concussions, but it may take months for the symptoms to disappear. In rare instances, people experience emotional, mental or physical changes that are more lasting. Repeat concussions should be avoided because even though they are rarely fatal, they can increase the chances of getting permanent brain damage.

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