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Signs of a Concussion

Written by Ada’s Medical Knowledge Team

Updated on

What is concussion?

Concussion is a condition that occurs as a result of a mild traumatic brain injury (mTBI). It involves the short suspension of the brain’s normal function as it responds to the impact of an injury to the head – such as a knock or fall.

Concussion can result from any injury in which the brain is jolted from its usual position to the extent that it hits the inner wall of the skull. This trauma can stretch or damage brain cells. 1 This means that, after trauma, it becomes increasingly likely that the normal movements of the brain inside the skull, which would normally not cause any damage to the brain, could go on to result in bruising and bleeding.

It is sometimes possible to see the outward signs of concussion, such as dizziness, nausea or confusion. In the immediate aftermath of the causal injury, concussion itself is initially a microscopic injury to the brain which will not be visually evident if the brain is scanned, e.g. by doing a CT scan. For this reason, many cases of concussion go unnoticed or undiagnosed.

People do not always exhibit or notice the physical or behavioral symptoms of concussion, so it is important to look out for signs of concussion in all cases where a person has sustained an injury to the head. Although people experiencing concussion may display perceptible symptoms such as nausea, headaches and slurred speech, these may only begin to occur several hours or days after the injury itself.

It is important to see a doctor following any injury to the head in order to assess the likelihood of concussion and devise a recovery plan. 2 Recovery techniques will focus on resting sufficiently and avoiding strenuous physical and mental activity, so as to allow the brain to recuperate, thereby limiting the likelihood of any possible concussion developing into a long-term condition.

If you’re unsure whether you, or somebody else, is showing signs of concussion after a recent head injury, try downloading the Ada app for a free symptom assessment.

Signs of concussion in adults and teenagers

Concussion can cause a person to experience a temporary loss of consciousness, lasting for seconds, or minutes. Not everybody who experiences concussion loses consciousness, but, in cases where loss of consciousness does occur, the longer a person who has sustained a head injury remains unconscious, the more severe their concussion is likely to be. 3 Medical attention should be sought in all cases where an injury to the head has resulted in loss of consciousness.

In addition to a possible loss of consciousness, a person with concussion may experience one or more of the symptoms from this checklist: 4

  • Feeling confused
  • Feeling as though one is in a blur or fog
  • Forgetfulness, often extending to the circumstances which caused the concussion
  • Headache
  • Feeling pressure in the head
  • Ringing in the ears
  • Seeing stars
  • Slurred speech
  • Nausea
  • Dizziness

Many people recover from concussion unaided, without necessarily noticing that they have experienced the condition. However, it is possible to develop post-concussion syndrome, where the symptoms of concussion persist for weeks, months or years after the injury took place. To ensure a full recovery from concussion and prevent this outcome with appropriate aftercare, it is important to look out for signs of concussion in anybody who has experienced a head injury.

Read more about concussion »

How long after a head injury do signs of concussion appear?

It is very common for additional symptoms of concussion to appear in the hours or days after the causal injury. The time it takes for the signs of concussion to be present after a head injury varies considerably between people. One may be able to see some symptoms, such as a temporary loss of consciousness, in the immediate time period after the primary injury. Further signs of concussion, such as nausea or dizziness, can begin to appear within minutes, or can be delayed, or go unnoticed, for hours or days after the causal injury.

Symptoms of concussion which may appear later on include: 5

  • Irritable mood and changes in personality
  • Sensitivity to light, noise and other external stimuli
  • Reduced ability to concentrate
  • Poor memory
  • Difficulty sleeping
  • Changes to the senses of taste and smell
  • Depression

If you’re unsure whether you, or somebody else, is showing signs of concussion after a recent head injury, try downloading the Ada app for a free symptom assessment.

Signs of concussion in children

While adults and teenagers tend to experience some or all of the symptoms of concussion listed above, it can be difficult to spot the signs of concussion in children, toddlers and babies, especially as they may not be able to verbalize how they are feeling.

It is therefore vital that caregivers remain alert to the possibility that any children or infants who have experienced an injury to the head could be at risk of concussion. Monitor kids who have sustained a head injury for the signs of concussion associated with their age group and seek medical attention in all cases of suspected concussion. 6

Signs of concussion in babies

Signs of concussion in babies may include:

  • A bump or bruise to the head
  • Changed sleeping habits; sleeping more or less can both be indicators of concussion
  • Crying when the head is moved
  • Vomiting
  • Changes in mood, especially increased irritability
  • Difficulty feeding

Signs of concussion in toddlers

Toddlers who are able to talk will generally be able to indicate whether they are feeling different from normal. This can be helpful in establishing whether a toddler may have concussion.

Signs of concussion in toddlers may include:

  • Nausea and/or vomiting
  • Behavioral changes
  • Loss of interest in their usual activities
  • Sleeping more or less
  • Excessive crying
  • Headache

Signs of concussion in children (aged two and above)

Children aged two and above tend to display more behavioral changes related to concussion, similar to those experienced by adults.

Signs of concussion in children may include:

  • Sensitivity to light and noise
  • Double vision
  • Dizziness, nausea and/or vomiting
  • Drowsiness
  • Irritability
  • Difficulty balancing
  • Sleeping more or less
  • Difficulty concentrating
  • Poor memory
  • Confusion about recent events
  • Changes in mood, especially sadness or nervousness

Causes of concussion

Concussion is the most common kind of mild traumatic brain injury. It occurs as the result of a knock or jolt to the head, which causes the brain to move from its normal position inside the skull, damaging the cells in the affected area. Activities which may result in head injuries, such as driving motor vehicles and playing sports, increase one’s chances of experiencing concussion. Knocking one’s head as a result of falling over can also result in concussion and is a principal cause of concussion in infants and the elderly.

The leading causes of concussion recorded by emergency departments are: 2

  • Falling
  • Injuries related to motor vehicles
  • Accidentally being struck by or against an object
  • Assaults
  • Playing sports

According to the <i>Journal of Athletic Training</i>, approximately 300, 000 sport-related traumatic brain injuries occur in the United States annually, of which the majority are concussions. Motor vehicle crashes are the second most common cause of traumatic brain injury among people aged 15 to 24 years, and the most common cause of concussion across all age groups. 3

When to seek medical attention after a head injury

Many people make a rapid and full recovery from concussion. Nevertheless, it is important to consult a doctor in all cases where the condition is suspected. Failing to rest and recuperate adequately when one has concussion can lead to the development of post-concussion syndrome, where the signs of concussion persist for weeks or months after the initial injury.

Seek immediate medical attention in all cases where:

  • A person of any age is feeling or behaving differently after sustaining an injury to the head, even if only one or two of the signs of concussion are apparent
  • A child has experienced any kind of head injury that is more significant than a slight bump to the head, 7 i.e. any injury which causes bruising or bleeding or causes the child to indicate that they are experiencing pain

There is usually no need to seek medical attention for suspected concussion after a minor head injury if a person of any age:

  • Remains alert
  • Has not been unconscious for any amount of time
  • Responds normally to speech
  • Is not dizzy, nauseous, or displaying any other age-appropriate indicators of concussion

Concussion danger signs

A person affected by concussion involving a temporary loss of consciousness and/or a period of post-traumatic amnesia will need immediate medical attention in order to establish the impact of their traumatic brain injury (TBI) on their brain, and to devise a recovery plan.

Returning to day-to-day activities, especially playing sports, while suffering from an initial concussion can worsen its physiological and psychological impact, and can also increase the risk of incurring a second concussion or developing post-concussion syndrome. 8

Emergency care should be sought after a head injury if a person of any age presents with any of the concussion danger signs, which include: 9 10

  • Losing consciousness for more than 30 seconds 11
  • Having headaches repeatedly, or which worsen over time
  • Visible and persistent bumps, bruising or swelling anywhere on the head, particularly in children and infants
  • Nausea and vomiting getting worse instead of better
  • Becoming increasingly irritable over a number of days following the injury
  • Stumbling or being clumsy
  • Feeling disorientated, confused or experiencing difficulty recognizing familiar concepts
  • Slurred or altered speech
  • Seizures
  • Distorted vision and blurriness
  • Dilated pupils or pupils of different sizes

Additional concussion danger signs in babies and toddlers may include: 10

  • Refusing to nurse or eat
  • Inconsolable crying

If any of the concussion danger signs are present, seek immediate medical attention. Any of these symptoms may indicate that the kind of head injury sustained is more serious than a concussion. For example, in rare cases, a collection of blood, called a hermatota, can form inside the head following a blow or bump, squeezing the brain against the skull. 10

Concussion FAQs

Q: Is it safe for someone to fall asleep if they have signs of concussion?
A: Yes. It is a myth that it is dangerous to fall asleep following a concussion. It was once believed that falling asleep after becoming concussed could result in slipping into a coma, but this idea has been discredited by medical research. 12

In fact, getting plenty of rest is of principal importance in recovering from concussion and allowing the trauma to the brain to heal. Consulting a doctor, followed by sleeping and/or resting is the best course of action for anyone affected by concussion, unless the doctor has advised that the concussed person needs to undergo further treatment related to the TBI.

Q: Is it possible to tell whether a person has a mild or a severe concussion?
A: Symptoms such as loss of consciousness, slurred or altered speech, or confusion, persistent nausea and vomiting in the immediate aftermath of a concussion, may be signs that a person has been severely concussed, or has another, more serious form of head injury.

In diagnosing concussion, doctors once used grading systems to establish whether a person’s condition was slight or severe, particularly in sports medicine. The grading system would typically be used with the end goal of determining how much recovery time an injured player would need before returning to play.

The use of grading systems is now less common, but a popular and scientifically proven means of assessing concussion is the Glasgow Coma Scale (GCS). The GCS is a practical test for assessing how greatly a person’s consciousness is impaired. It can be used for all patients that have any kind of impairment of consciousness, including concussion. It is routinely used to screen a person’s neurological state if any kind of trauma to the head is suspected, for example, after an accident.

The GCS can help monitor the course of a person’s symptoms over time and can help doctors in selecting appropriate treatment for a person to make a full recovery, for example, whether they will need emergency care or a breathing tube (intubation). As standard practice, doctors will evaluate concussion and advise on a recovery program on a case-by-case basis, taking all of a person’s symptoms and case-history into account.

Q: What changes to the pupils in the eyes could be signs of a concussion?
A: Dilated pupils or pupils of unequal sizes could indicate that a person is affected by a severe concussion or a more serious form of TBI than concussion. However, this only applies if the difference in size between the pupils is greater than one millimeter. Differences in size between pupils of between half a millimeter and one millimeter are completely normal and quite common.

Concussion and other forms of TBI can prevent the eyes from focussing easily on relevant objects, and/or working as a pair. To identify this, eye movement tracking tests are sometimes performed in the diagnosis of a concussion. These are activities, such as watching moving objects on a screen, which test the reflexes of the pupils. 13

Q: How long do the signs of concussion last?
A: In most people, perceptible symptoms of concussion resolve within around two weeks. A recent study on the effect of cognitive activity level on the duration of post-concussion symptoms has revealed that the more one rests one’s brain ‒ including refraining from activities such as using computers and smartphones ‒ during the period after concussion, the more quickly normal brain function will be restored.

When post-concussion syndrome is not present, full recovery from concussion ‒ including the physical recovery of the brain from the injury, which will be imperceptible to the affected person ‒ can take as long as up to 100 days. The time it takes to recover from concussion can be significantly reduced, to around 20 or 30 days, by ensuring that one refrains from returning to one’s normal day-to-day activities and rests appropriately. 14

How long should I look out for the signs of concussion after a head injury?
A: In some, cases, signs of concussion may appear in the immediate aftermath of a concussion. For other people, signs of concussion may not appear straight away, and may develop in the days or weeks following the primary injury. It is therefore important to be aware that any symptoms experienced later on may be signs of concussion, and to have them investigated by a doctor.

Q: What is post-concussion syndrome (PCS)?
A: Post-concussion syndrome (PCS) is a rare condition in which people continue to experience symptoms related to their concussion for weeks, months or even years, if left untreated after the injury that led to their concussion. These may include sleeping problems, difficulty remembering things, fatigue, dizziness, headaches, depression and sensitivity to noise and light. Treatment will involve addressing the specific symptoms that each person with PCS experiences. With appropriate medical supervision, PCS relieves over time in most cases.

Read more about Post-concussion Syndrome »

Q: What can a person do to facilitate effective recovery from concussion?
A: The most important element of recovering from concussion is allowing the brain to rest, both through getting sufficient sleep and ensuring that one takes a break from one’s normal working or school hours and from sporting activities.

Returning to work or school before the brain has recovered to the point where symptoms are no longer present can increase the chances of prolonging the concussion. If the symptoms of concussion return, this may be an indicator that one has rushed the recovery process and returned to one’s usual routine too soon. Medical attention should then be sought and a revised recovery plan devised.