The symptoms of a concussion can be subtle and may not occur right away. 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 amnesia usually involves forgetting the event that caused the concussion.

Physical symptoms of a concussion may include:

• Headache.
• Ringing in the ears.
• Nausea.
• 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 or "seeing stars."

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.
• Listlessness and tiring easily.
• Irritability and crankiness.
• Loss of balance and unsteady walking.
• Excessive crying.
• 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 nausea.
• 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 eye, known as the pupils, may be bigger than usual or unequal sizes.
• Ringing in the ears that doesn't go away.
• Weakness in the arms or legs.
• 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.
• Changes in physical coordination, such as stumbling or clumsiness.
• Seizures or convulsions.
• Dizziness that doesn't go away or that goes away and comes back.
• Symptoms that worsen over time.
• 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 immediately following a concussion. Experts recommend that adult, child and adolescent athletes with concussions not return to play on the same day as the injury. Even if a concussion is suspected, experts recommend not returning to activities that can put the athlete at risk of another concussion. Gradual return to learning and physical activity is individual and depends on the symptoms. It should always be supervised by a healthcare professional.

During a concussion, the brain slides back and forth against the inner walls of the skull. This forceful movement can be caused by 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 period of time. Sometimes a mild 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.

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 and supervision when playing high-risk sports.
• Auto accidents.
• Pedestrian or bicycle accidents.
• Military combat.
• Physical abuse.

Having had a previous concussion also increases the risk of having another.

Potential complications of concussion include:

• Post-traumatic headaches. Some people experience concussion-related 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 after a brain injury.
• Persistent post-concussive symptoms, also known as post-concussion syndrome. A small number of people may have multiple symptoms that last longer than expected. Longer lasting symptoms may include headaches, dizziness and trouble with thinking. If these symptoms persist beyond three months, they're called persistent post-concussive symptoms.
• Effects of multiple brain injuries. Researchers are studying the effects of repeated head injuries that don't cause symptoms, known as subconcussive injury. At this time, there's no conclusive evidence that these repeated brain injuries affect brain function.
• Second impact syndrome. Rarely, experiencing a second concussion before symptoms of a first concussion go away may result in rapid brain swelling. This can lead to death. It's important that athletes never return to sports while they're still experiencing symptoms of concussion.

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

• Wear protective gear during sports and other recreational activities. Make sure the equipment fits properly, is well maintained and is worn correctly. Follow the rules of the game and practice good sportsmanship.

  Be sure to wear a helmet when bicycling, motorcycling, snowboarding or doing any activity that may result in a head injury.

• Buckle your seat belt. Wearing a seat belt may prevent serious injury, including head injury, during a traffic accident.
• Make your home safe. Keep your home well lit. Keep your floors free of anything that might cause you to trip and fall. Falls around the home are a leading cause of head injury.
• Protect your 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.
• Educate others about concussions. Educate coaches, athletes, parents and others about concussions to help spread awareness. Coaches and parents also can help encourage good sportsmanship.

To diagnose a concussion, your healthcare professional evaluates your symptoms and reviews your medical history. You may need tests that help diagnose a concussion. Tests 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 and 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. Imaging tests may determine whether the injury has caused bleeding or swelling in the skull.

A computerized tomography (CT) scan of the head is the standard test in adults to assess the brain 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 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. An MRI uses powerful magnets and radio waves to produce detailed images of your brain.

Observation

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

Or your healthcare professional may agree that you or your child can be observed at home. Have someone stay with you and check on you for at least 24 hours to ensure that your symptoms aren't getting worse.

There are steps you can take to help your brain heal and speed recovery.

Physical and mental rest

In the first couple of days after a concussion, relative rest allows your brain to recover. Healthcare professionals recommend that you physically and mentally rest during this time. However, complete rest, such as lying in a dark room without any stimuli, does not help recovery and is not recommended.

In the first 48 hours, limit activities that require a lot of concentration if those activities makes your symptoms worse. This includes playing video games, watching TV, doing schoolwork, reading, texting or using a computer.

Don't do physical activities that increase your symptoms. This may include general physical exertion, sports or any vigorous movements. Don't do these activities until they no longer provoke your symptoms.

After a period 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.

Light exercise and physical activity as tolerated starting a couple of days after injury have been shown to speed recovery. Activities might include riding a stationary bike or light jogging. But don't engage in any activities that have a high risk of another head impact until you are fully recovered.

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 different therapies. 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.

Some physical activity can help speed brain recovery. Specific return to physical activity sport protocols 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). Don't take other pain relievers such as ibuprofen (Advil, Motrin IB, others) and aspirin. These medicines may increase the risk of bleeding.

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 right away. 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. The most important thing for you to do while waiting for your appointment is not to do activities that cause or worsen symptoms. Don't play sports or do vigorous physical activities. Minimize stressful or prolonged mental tasks. At the time you make the appointment, ask what steps you or your child need to take to encourage recovery or prevent another injury. Experts recommend that athletes not 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?
• What is the risk of long-term complications?
• When will it be safe to return to competitive sports?
• When will it be safe to resume vigorous exercise?
• Is it safe to return to school or work?
• Is it safe to drive a car or operate power equipment?
• I have other medical conditions. How can they be managed together?
• Should I see a specialist? What will that cost, and will my insurance cover a visit to a specialist? You may need to call your insurance provider for some of these answers.
• Are there any brochures or other printed material that I can take home with me? What websites do you recommend?

In addition to the questions that you've prepared, don't hesitate to ask questions that come up during your appointment.

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 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 since the injury?
• Have you had any issues with memory or concentration since the injury?
• Have you noticed any sensitivity or changes with your vision and hearing?
• Have you had any mood changes, including irritability, anxiety or depression?
• Have you felt sluggish or easily fatigued since the injury?
• Are you having trouble sleeping or waking from sleep?
• Have you noticed changes in your sense of smell or taste?
• Do you have any dizziness?
• What other symptoms are you concerned about?
• Have you had any previous head injuries?

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. 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.