Concussion

What Is a Concussion? Symptoms, Causes, Diagnosis, and Treatment

Ashley Welch
By Medically Reviewed by 
Reviewed:
Medically Reviewed

A concussion is a mild traumatic brain injury (mTBI) that is caused by a blow to the head or chest, whiplash, or other violent shaking of the head and body. It can occur with or without the loss of consciousness and may lead to temporary cognitive problems.

Concussions are the most common form of TBI.

Most people who get a concussion will recover, but for some people symptoms can last days, weeks, or longer. The recovery period may be longer for older adults, young children, and teens. Recovery may also take longer for people with a personal or family history of migraine, ADHD, or other learning disorders.

Common Questions & Answers

What are the symptoms of a concussion?
Signs of a concussion include headache, blurred vision, dizziness, nausea or vomiting, sensitivity to light or noise, balance problems, and tiredness. Someone with a concussion may also have difficulty thinking clearly, concentrating, and remembering new information, and have erratic emotions such as sadness, irritability, and anxiety.
When should you go to the ER for a concussion?
Contact your doctor if you've experienced a blow to the head and have a headache that won’t go away, weakness or numbness, repeated vomiting or nausea, or slurred speech. A person should go to the ER immediately if they look very drowsy or cannot wake up, have seizures or convulsions, cannot recognize people or places, or lose consciousness.
How long does it take to recover from a concussion?
Symptoms of concussions will typically subside on their own within one to six weeks. For some people, symptoms last longer and can cause complications, including headaches and dizziness that won’t go away. If a second concussion occurs before the first one has had time to completely heal, the brain can severely swell, which can turn fatal.
How do you heal from a concussion?
The most important step in recovery from a concussion is to get plenty of rest. Physically and mentally demanding activities should also be avoided until symptoms subside. Medication may be prescribed to deal with headaches, nausea, or sleep problems. Sometimes, physical therapy, occupational therapy, and vestibular therapy are necessary.

What Are the Symptoms of a Concussion?

Especially early on, symptoms of a concussion may be overlooked or mistaken for less-serious health problems. Sometimes people with a concussion do not recognize the symptoms, confuse them with something else, or don’t want to admit there's something wrong. Others may not understand what is happening to their bodies and how it is affecting their day-to-day lives.

That's why it’s especially important for everyone to know the signs of a concussion and be vigilant in looking out for them, especially when someone has experienced a blow to the head.

Symptoms of a concussion fall into four categories: physical, cognitive, emotional or mood-related, and sleep.

Physical symptoms of a concussion include:

  • Headache
  • Fuzzy or blurred vision
  • Nausea or vomiting
  • Dizziness
  • Sensitivity to noise or light
  • Balance problems
  • Feeling tired or having no energy

Cognitive symptoms of a concussion include:

  • Difficulty thinking clearly
  • Feeling slowed down
  • Difficulty concentrating
  • Difficulty remembering new information
  • Brain fog or grogginess

Emotional symptoms of a concussion include:

  • Irritability
  • Sadness
  • Erratic emotions
  • Nervousness or anxiety

Sleep symptoms of a concussion include:

  • Sleeping more or less than usual
  • Difficulty falling asleep
  • Daytime drowsiness
Typically a person will experience symptoms within minutes of the injury to the head, but sometimes concussion symptoms can take several hours or days to appear. Symptoms can also change after a few days or appear with stress.

Although rare, a person with a concussion can develop a dangerous blood clot or brain bleed that pushes the brain against the skull, which can sometimes be fatal.

Contact your doctor or local emergency department immediately if you experience any of the following danger signs after a blow, bump, or jolt to the body or head:

  • A headache that gets worse and does not go away, perhaps even the worst headache of your life
  • Weakness, numbness, or decreased coordination
  • Repeated vomiting or nausea
  • Slurred speech

If you’re caring for someone who you think might have a concussion, take them to the emergency room immediately if they:

  • Look very drowsy or cannot wake up
  • Have one pupil larger than the other
  • Have seizures or convulsions
  • Cannot recognize people or places
  • Are getting more confused, restless, or agitated
  • Are behaving unusually
  • Lose consciousness

Danger signs in children can include all the above, as well as refusal to nurse or eat and crying that won’t stop.

Learn More About Concussion Symptoms

What Causes a Concussion?

A concussion is caused by a blow, bump, or jolt to the head or chest, a violent shaking of the head or upper body (as in whiplash, for instance), or a penetrating injury, such as a gunshot wound. 

The most common causes of traumatic brain injuries in the United States include falls, firearm-related injuries, motor vehicle crashes, and assault. Falls account for about half of all TBI-related hospitalizations in the United States.

Contact sports are likely the most common cause of concussions. According to the Brain Injury Research Institute, an estimated 1.6 to 3.8 million sports and recreation-related concussions occur every year in the United States.

How a Concussion Is Diagnosed

A concussion is often diagnosed in an emergency room after a fall or accident or after an incident during a sports game. A concussion can also be diagnosed later on, when a person seeks treatment following symptoms that started after the initial blow.

Diagnosis is a several-step process that involves the following:

  • Interview A doctor will document the extent of any loss of consciousness or loss of memory leading up to the event, or loss of memory of the event or after the injury, as well as any other symptoms, such as headache, feeling dazed or confused, dizziness, or fatigue.
  • Examination The doctor will look for any neurological signs and symptoms by testing strength, sensation, reflexes, coordination, balance, vision, hearing, mental status, nerve functions, and other functions to determine the severity of the brain injury.
  • Brain imaging Sometimes brain imaging may be recommended for patients with symptoms of severe headaches, seizures, repeated vomiting, or symptoms that continue to worsen. A cranial computerized tomography (CT) scan can determine whether the injury is severe and has caused bleeding or swelling in the brain. Magnetic resonance imaging (MRI) can determine if the brain has undergone any changes and can help diagnose complications after a concussion. A normal CT or MRI does not rule out a concussion, though.
  • Observation Some patients may need to be hospitalized overnight for observation following a concussion. It may also be possible to be observed at home. A caregiver should observe the affected person closely for at least 24 hours to make sure symptoms aren’t getting worse. 
In recent years, researchers have been working on more effective ways to diagnose concussions. In January 2021, the U.S. Food and Drug Administration (FDA) cleared the first rapid handheld blood test for concussions. The test requires a small blood sample from the arm, from which plasma is extracted and tested. Results are available within 15 minutes. A negative result eliminates the need for a CT scan. Abbott, the maker of the test, expects it to become available for everyday use by clinicians.

How Long Does a Concussion Last?

Most people who get a concussion will recover within a few days. But for some people symptoms can last for weeks or even longer.

How quickly someone improves depends on many factors, including the severity of the concussion, their age, how healthy they were before the injury, and how well they care for themselves after the concussion.

The recovery period may be longer for older adults, young children, and teens.

How a Concussion Is Treated

Most people recover completely from a concussion. The most important step in concussion recovery is getting plenty of rest, which is necessary to help the brain heal. It’s also important to avoid physically and mentally demanding activities until symptoms subside.

Medication may be prescribed to deal with headache pain, nausea, or sleep problems related to the traumatic brain injury.

Learn More About Treatments for a Concussion

Possible Complications From a Concussion

Symptoms of most concussions and other mild TBIs will go away on their own within a couple of weeks. But for some people, symptoms last longer and may cause complications.

These complications can include post-concussion syndrome, which is characterized by headaches and dizziness that will not go away; post-traumatic vertigo, or dizziness that accompanies movement.

Second impact syndrome is a rare but serious potential complication that happens when a second concussion occurs before the first one has had time to completely heal. This can lead to rapid and severe brain swelling, which can turn fatal.

Research has also linked moderate to severe brain trauma with an increased risk of Alzheimer’s disease and other types of dementia. The Alzheimer’s Association has called for more research to better understand the link.

Learn More About the Possible Complications of Concussions

Research and Statistics: How Many People Are Affected by Concussions?

According to the most recent numbers from the CDC, approximately 2.9 million cases of traumatic brain injury were diagnosed in emergency rooms, with 75 percent of those being mild TBIs, or concussions. This is surely an underestimate, though, as many people don’t seek treatment for concussions.

Moderate and severe TBIs, but not concussions, led to 223,050 hospitalizations in 2018 and 60,611 deaths in 2019. This is equivalent to 610 TBI-related hospitalizations and 166 TBI-related deaths each day. But again, the CDC says these numbers are actually much higher, as many TBIs go untreated.

Males are two times more likely to be hospitalized and three times more likely to die from a TBI than females. Older adults age 75 or older have the highest rates of TBI-related hospitalizations and death. This age group accounts for 32 percent of all TBI-related hospitalizations and 28 percent of TBI-related deaths.

In children age 17 and younger, there were 16,480 TBI-related hospitalizations and 2,476 TBI-related deaths in 2019.

Related Conditions: Sleep Disorders and Brain Injury

Sleep disturbance is common following a traumatic brain injury like a concussion and affects 30 to 70 percent of individuals.

Common sleep problems include insomnia, sleep apnea, difficulty staying asleep, daytime sleepiness, and narcolepsy.
One study of U.S. veterans found that those who sustained mild TBIs were 49 percent more likely to develop sleep disorders for up to five years following those injuries.

Sleep disturbances can occur regardless of the severity of a brain injury. Research suggests that sleep disorders affect individuals with a concussion or mild TBI more severely.

This could be because the individual is more aware of their deficits or increased social pressure to reintegrate into their daily life, since a concussion is often viewed as a less-severe form of brain injury.

It's important to talk to your doctor about any sleep problems you're experiencing with a TBI so that proper treatment can be administered. Treatment may include sleep medication, cognitive behavioral therapy, or other behavioral modifications, according to past research.

Learn More About Sleep Disorders and Brain Injury and How One Woman Deals With the Problem

Concussions in Males Versus Females

For many years, doctors treated concussions in men and women the same. But research now shows that a traumatic brain injury has different effects on the two sexes. For example, research shows that female athletes sustain more concussions than males.

Females also take longer to recover and experience more severe symptoms.

Learn More About How Concussions Are Different in Males Versus Females

Sports and Concussions

A common cause of concussion is trauma during a professional or recreational sport, including but not limited to football, soccer, and hockey.

Though football seems to get the most attention when it comes to concussions, the injury is common in many other sports, especially in female sports. Concussion rates are high in ice and field hockey, lacrosse, soccer, basketball, volleyball, cheerleading, gymnastics, wrestling, baseball, and softball.

To treat concussions in sports, most post-concussion rehab protocols use exercise of graded intensity (rather than pure rest) before the person returns to play.

Learn More About Sports and Concussions

Concussions in Children

If you suspect that your child has had a concussion, go to the emergency room if you see any of the following signs:

  • Loss of consciousness
  • Trouble walking
  • Blurred vision
  • Slurred speech
  • Confusion
  • Severe headache, or a headache that gets worse

Call your doctor if your child complains of headache, dizziness, or memory problems after a hit on the head. The doctor will perform a physical exam and will test things like balance, coordination, and nerve function. A brain scan might also be performed to rule out internal bleeding.

Fast action can lead to a proper diagnosis and treatment to help your child recover. Since concussions are unique to each individual, your child’s doctor will prescribe treatment based on specific symptoms. If the concussion is not severe enough to warrant a trip to the hospital, your child’s doctor will provide instructions for home care.

Home care includes the following:

  • Physical rest until symptoms subside
  • Mental rest and avoidance of mentally taxing activities until symptoms subside
  • Eating well and avoiding caffeine
  • Avoiding bright lights or loud noises, which can make symptoms worse

Note that there is no evidence to support waking a child every few hours when they are sleeping to check for symptoms. Also, children can usually return to their normal activities within a few weeks. It’s important to wait until their doctor gives the go ahead to do so, and they and should stop what they are doing if symptoms return.

Learn More About Concussions in Children and How One Mom’s Swift Action Led to Her Daughter’s Speedy Recovery From a Concussion

Concussion Quiz

Headache, dizziness, blurred vision — how well do you know the signs of a concussion? In order to receive prompt treatment and prevent complications, it’s important to be aware of the ways a concussion can occur and the symptoms that may be present.

Learn More About Concussions by Taking Our Quiz

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