Concussion

Date Updated: 07/18/2026

Overview

A concussion is a mild traumatic brain injury that affects brain function. Effects are often short term and can include headaches and trouble with concentration, memory, balance, mood and sleep.

Concussions usually are caused by an impact to the head or body. However, not everyone who experiences a blow to the body or head has a concussion.

Some concussions cause the person to lose consciousness, but most do not.

Falls are the most common cause of concussions in adults and very young children. In children and teenagers, concussions are common among athletes who play a contact sport, such as American football or soccer. Most people recover fully after a concussion.

Symptoms

The symptoms of a concussion can be subtle. Symptoms may occur right away or in the hours and days after an injury. Symptoms can last for days, weeks or even longer.

Common symptoms after a mild traumatic brain injury are headache, confusion and loss of memory, known as amnesia. The person may forget the event that caused the concussion.

Physical symptoms of a concussion may include:

Headache.
Ringing in the ears.
Upset stomach.
Vomiting.
Fatigue or drowsiness.
Blurry vision.

Other symptoms of a concussion include:

Confusion or feeling as if in a fog.
Amnesia surrounding the event.
Dizziness.

A witness may observe these symptoms in the person with a concussion:

Temporary loss of consciousness, though this doesn't always occur.
Slurred speech.
Delayed response to questions.
Dazed appearance.
Forgetfulness, such as asking the same question over and over.

Some symptoms of a concussion occur right away. But sometimes symptoms may not occur for days after the injury, such as:

Trouble with concentration and memory.
Irritability and other personality changes.
Sensitivity to light and noise.
Trouble with sleep.
Feeling emotional or depressed.
Changes in taste and smell.

Symptoms in children

Concussions can be hard to recognize in infants and toddlers because they can't describe how they feel. Concussion clues may include:

Dazed appearance.
Lack of interest and tiring easily.
Irritability and crankiness.
Loss of balance and unsteady walking.
Crying more than usual.
Change in eating or sleeping patterns.
Lack of interest in favorite toys.
Vomiting.

When to see a doctor

See a healthcare professional within 1 to 2 days if:

You or your child experiences a head injury, even if emergency care isn't required.

Children and adolescents need to see a healthcare professional trained in evaluating and managing pediatric concussions.

Seek emergency care for an adult or child who experiences a head injury and any of these symptoms:

Repeated vomiting or upset stomach.
A loss of consciousness lasting longer than 30 seconds.
A headache that gets worse over time.
Fluid or blood draining from the nose or ears.
Vision or eye changes. For example, the black parts of the eyes, known as the pupils, may be bigger than usual or not equal sizes.
Ringing in the ears that doesn't go away.
Weakness in the arms or legs.

Also seek emergency care for any of these symptoms:

Changes in physical coordination, such as stumbling or clumsiness.
Serious changes in behavior.
Confusion or disorientation. For example, the person may not recognize people or places.
Slurred speech or other changes in speech.
Obvious changes to mental function.
Seizures or convulsions.
Dizziness that doesn't go away or that goes away and comes back.

Also watch for and seek emergency care for symptoms that worsen over time and for large head bumps or bruises, such as bruises around the eyes or behind the ears. It's especially important to seek emergency care if these symptoms appear in infants under 12 months of age.

When symptoms occur in athletes

Never return to play or vigorous activity right after a concussion or on the same day as an injury. This is true even if a concussion is suspected. Also don't do any activities that can put you at risk of another concussion. Depending on your symptoms, you may need to gradually return to learning and physical activity. The steps you take to get back to your typical routine should always be supervised by a healthcare professional.

Causes

A concussion is caused by an event that affects your brain. During a concussion, the brain slides back and forth against the inner walls of the skull. This can be due to a violent blow to the head and neck or upper body. It also may be caused by the sudden acceleration or deceleration of the head. This may happen during a car crash, a fall from a bike or from a collision with another player in sports.

These movements injure the brain and affect brain function, usually for a brief time. Sometimes a traumatic brain injury can lead to bleeding in or around the brain, causing prolonged drowsiness, confusion and, sometimes, death. Anyone who experiences a brain injury needs to be monitored in the hours afterward and seek emergency care if symptoms worsen.

Risk factors

Events and factors that may increase the risk of a concussion include:

Activities that can lead to falls, especially in young children and older adults.
High-risk sports such as American football, hockey, soccer, rugby, boxing or other contact sports.
Not using proper safety equipment or not having supervision when playing high-risk sports.
Auto accidents.
Pedestrian or bicycle accidents.
Military combat.
Physical abuse or assault.

A previous concussion also increases the risk of having another.

Complications

Potential complications of concussion include:

Post-traumatic headaches. Some people have headaches for several days to weeks after a brain injury.
Post-traumatic vertigo. Some people experience a sense of spinning or dizziness for days or weeks.
Persistent postconcussive symptoms, also known as postconcussion syndrome. Some people may have symptoms that last longer than expected. These symptoms may include headaches, dizziness and trouble with thinking. If they last longer than three months, they're called persistent postconcussive symptoms.
Effects of multiple brain injuries. Researchers are studying the effects of repeated head injuries. At this time, the evidence that repeated concussions have long-term effects is mixed. Some studies suggest that former athletes in contact sports are at higher risk of developing trouble with brain function and mental health later in life. However, other studies suggest that the development of trouble with brain function and mental health in athletes in contact sports may be more strongly related to other factors.
Second impact syndrome. This rare but potentially fatal syndrome involves rapid brain swelling that occurs when a person has a second head injury before fully recovering from a first injury. It is important that athletes suspected of having a concussion be removed from play right away and not return until they have recovered.

Prevention

These tips may help you prevent or minimize the risk of a concussion:

Wear protective gear during sports and other activities. This includes a helmet when bicycling, motorcycling, snowboarding or doing any activity that may result in a head injury. Make sure the equipment fits properly, is well maintained and is worn correctly.
Buckle your seat belt. Wearing a seat belt may prevent a head injury during a traffic accident.
Make your home safe. Keep your home well lit and your floors free of items that can lead to trips and falls. Falls around the home are a leading cause of head injury.
Protect young children. To help lessen the risk of head injuries in children, block off stairways and install window guards.
Exercise regularly. Exercise strengthens your leg muscles and improves your balance. This can help prevent falls.
Educate others about concussions. Educate coaches, athletes, parents and others about concussions to help spread awareness. Athletes should not return to play on the same day if a concussion is suspected or confirmed.

Diagnosis

To diagnose a concussion, your healthcare professional evaluates your symptoms and reviews your medical history. You may need tests. They may include a neurological exam, cognitive testing and imaging tests.

Neurological exam

Your healthcare professional asks detailed questions about your injury and then performs a neurological exam. This evaluation includes checking your:

Vision.
Hearing.
Strength.
Sensation.
Balance.
Coordination.
Reflexes.

Cognitive testing

Your healthcare professional may conduct several tests to evaluate your thinking skills, also known as cognitive skills. Testing may evaluate several factors, including your:

Memory.
Concentration.
Ability to recall information.

Imaging tests

Brain imaging may be recommended for some people who have had a concussion. Imaging may be done in people with symptoms such as bad headaches, seizures, repeated vomiting or symptoms that are becoming worse. These tests can tell your healthcare professional if the injury caused bleeding or swelling in or around the brain.

If symptoms are serious enough to require imaging, a computerized tomography (CT) scan of the head is the standard test right after injury. A CT scan uses a series of X-rays to obtain cross-sectional images of the skull and brain.

For children with a suspected concussion, CT scans are used only if specific criteria are met, such as the type of injury or if there are signs of a skull fracture. This is to limit radiation exposure in young children.

Magnetic resonance imaging (MRI) may be used to identify changes in your brain or to diagnose complications that may occur after a concussion. MRI uses a magnetic field and radio waves to produce detailed images of your brain.

Observation

After a diagnosis of a concussion, an adult or child may need to be hospitalized overnight for observation.

Or your healthcare professional might recommend observation at home. Have someone stay with you and check on you for at least 24 hours to make sure your symptoms aren't getting worse.

Treatment

Treatment of a concussion involves taking steps to help your brain heal and speed recovery.

Physical and mental rest

In the first couple of days after a concussion, healthcare professionals recommend relative rest. Don't do activities that increase your symptoms or put you at risk of another head injury. This may include general physical activity, sports or any vigorous movements. Also limit activities that require a lot of concentration if they make your symptoms worse. This includes playing video games, watching TV, doing schoolwork, reading, texting or using a computer.

Don't stop activity completely. Engaging in light physical activity as tolerated after an injury has been shown to speed recovery. Activities might include walking, riding a stationary bike or light jogging. Lying in a dark room doesn't help recovery and isn't recommended. However, don't do any activities that have a high risk of another head impact until you are fully recovered.

After a couple of days of relative rest, gradually increase daily activities if you can tolerate them without triggering symptoms. You can start both physical and mental activities at levels that do not cause a major worsening of symptoms.

Your healthcare professional may recommend that you have shortened school days or workdays. You may need to take breaks during the day or have modified or reduced school workloads or work assignments as you recover.

Your healthcare professional also may recommend therapy. You may need rehabilitation for symptoms related to vision, balance, or thinking and memory.

Returning to routine activity

As your symptoms improve, you may gradually add more activities that involve thinking. You may do more schoolwork or work assignments, or increase your time spent at school or work.

Specific protocols to return to sports or physical activity may be suggested by your healthcare professional. These typically involve specific levels of physical activity to make sure you return to activity safely. Don't resume contact sports until you are symptom-free and cleared by your healthcare professional.

Pain relief

Headaches may occur in the days or weeks after a concussion. To manage pain, ask your healthcare professional if it's safe to take a pain reliever such as acetaminophen (Tylenol, others). For the first one or two days, don't take other pain relievers such as ibuprofen (Advil, Motrin IB, others) and aspirin. These medicines may increase the risk of bleeding.

Preparing for an appointment

It's important for anyone who has a head injury to be evaluated by a healthcare professional, even if emergency care isn't required.

If your child has received a head injury that concerns you, call your child's healthcare professional. Depending on the symptoms, your healthcare professional may recommend that your child get medical care right away.

Here's some information to help you get ready for and make the most of your medical appointment.

What you can do

Be aware of any pre-appointment restrictions or instructions. As you wait for your appointment, it's important that you don't do activities that cause or worsen symptoms. Don't play sports or engage in vigorous physical activities. Limit stressful or prolonged mental tasks. At the time you make the appointment, ask what steps you or your child needs to take to encourage recovery or prevent another injury. Experts recommend that athletes don't return to play until they have been medically evaluated.
List any symptoms you or your child has been experiencing and how long they've been occurring.
List key medical information, such as other medical conditions for which you or your child is being treated. Include any history of head injuries. Also write down the names of any medicines, vitamins, supplements or other natural remedies you or your child is taking.
Take a family member or friend along. Sometimes it can be hard to remember all the information provided to you during an appointment. Someone who comes with you may recall something that you missed or forgot.
Write down questions to ask your healthcare professional.

For a concussion, some basic questions to ask include:

Do I have a concussion?
What kinds of tests are needed?
What treatment approach do you recommend?
How soon will symptoms begin to improve?
What is the risk of future concussions or long-term complications?

What to expect from your doctor

Being ready to answer your healthcare professional's questions may reserve time to go over any points you want to talk about in-depth.

You or your child should be prepared to answer the following questions about the injury and related symptoms:

Do you play contact sports? How did you get this injury?
What symptoms did you experience immediately after the injury?
Do you remember what happened right before and after the injury?
Did you lose consciousness after the injury?
Did you have seizures?
Have you had any previous head injuries?

Your healthcare professional may also ask:

Have you experienced nausea or vomiting since the injury?
Have you had a headache? How soon after the injury did it start?
Have you noticed any trouble with physical coordination, memory or concentration since the injury?
Have you noticed changes with your vision and hearing, or sense of smell or taste?
Have you had any mood changes, including irritability, anxiety or depression?
Have you felt sluggish or easily fatigued since the injury? Do you have any dizziness?
Are you having trouble sleeping or waking from sleep?

You might also be asked if there are other symptoms you're concerned about.

What you can do in the meantime

Before your appointment, don't do activities that increase your symptoms and risk another head injury. This includes not playing sports or activities that require vigorous movements.

Gradually resume your usual daily activities, including screen time, as you're able to tolerate them without worsening symptoms.

If you have a headache, acetaminophen (Tylenol, others) may ease the pain. For the first one or two days, don't take other pain relievers such as aspirin or ibuprofen (Advil, Motrin IB, others) if you suspect you've had a concussion. These may increase the risk of bleeding.