What is mild TBI or Concussion?

The least severe form of traumatic brain injury (TBI) is mild TBI (mTBI), also known as concussion. Anyone from infants to the elderly can get a concussion. Concussion can result in a range of signs and symptoms; no two concussions are alike. People can experience different concussion signs and symptoms, even if they have had a concussion before. Most people make a full recovery following a concussion, though the speed of recovery can differ from person to person. It’s important to seek medical attention following a witnessed or suspected concussion to rule out other forms of severe injury and assist with the recovery process.

What is a concussion?

A concussion is a short-term disturbance to normal brain function due to an external force impacting the head, neck, or body. The forces that occur during a concussion-causing event cause the brain to move within the skull, which in turn can cause the nerve cells and blood vessels in the brain to stretch and rebound. In some cases, concussion may also result in changes or damage to the ocular (eye) and vestibular (balance) systems.

Does a person need to be knocked out (lose consciousness) to have a concussion?

While many people believe that you need to be knocked out to be concussed, this is not actually the case. In fact, many concussions do not result in losing consciousness.

What are the leading causes of concussions?

Concussions are often associated with sporting activities, but these injuries more commonly occur in the course of everyday life.

Common causes of concussion include:

  • Falls
  • Motor vehicle crashes
  • Sporting activities
  • Workplace accidents
  • Assault

What are the signs and symptoms of a concussion?

Concussion can result in a range of signs (things you can see) and symptoms (things people say they are experiencing). No two concussions are alike. It is possible for people to experience different concussion signs and symptoms after their injury, even if they have had a concussion before.

Concussion signs and symptoms may appear at the time of injury or can develop and/or get worse over the following hours or days.

Because there are many different signs and symptoms that can be experienced after a concussion, it can be helpful to group them into the following categories: physical (somatic), cognitive, emotional, and sleep. A person may experience concussion signs and/or symptoms from any or just one category.

Physical Cognitive
  • Headache/Migraine
  • Dizziness
  • Nausea/vomiting
  • Balance problems
  • Changes in vision (e.g. blurry or double vision)
  • Sensitivity to light or noise
  • Difficulty thinking clearly
  • Difficulty concentrating
  • Difficulty paying attention
  • Poor memory
  • Feeling “not right”
Emotional Sleep
  • Anxiety
  • Feeling sad
  • More emotional
  • Irritability
  • Sleeping more than usual
  • Sleeping less than usual
  • Trouble falling or staying asleep
  • Fatigue

Red Flags: Emergency signs and symptoms

Red flags are signs and symptoms that may indicate more severe injury. Seek immediate medical attention if you or your loved one show any of the following:

  • Severe of increasing headache
  • Loss of consciousness or deteriorating conscious state
  • Seizure or convulsion
  • Repeated vomiting
  • Blurred, double or changes in vision
  • Neck pain or tenderness
  • Weakness or inability to move the body as usual
  • Sensations of numbness, tingling or burning in arms or legs
  • Increased confusion, agitation, or restlessness
  • Continual bleeding or fluid discharge from ear or nose

How long does it take for a person to recover from a concussion?

Most individuals recover fully from a concussion within a few days to weeks after their injury. However, for some individuals, the recovery process may be longer. Children, adolescents, and adults who experience concussion symptoms for more than 4 weeks after their concussion are said to be experiencing persistent post-concussion symptoms (PPCS). To learn more about PPCS, click here.

It’s important to note that individual recovery times are different for each person and the degree and speed of return to normal activities should be managed by a clinician to ensure symptoms are not made worse.

What are the long-term impacts of concussion?

Current knowledge about the long-term impacts of concussion is limited. However, this topic continues to be investigated by many researchers around the world and our understanding will improve over time.

It is unlikely that a single concussion will cause significant problems for an individual many years down the track, though return to activities of daily living, school, work, and sport/recreational activities can certainly be challenging for children and adults that are experiencing PPCS.

A growing body of scientific and media reports appear to suggest a link between repeated head injury and long-term impacts to a person’s mental, physical, and social wellbeing. While there have been calls for more high-level research into the long-term effects of concussion and repeated head injury, it is reasonable to consider that extensive exposure to repeated head impacts (such as those experienced by some professional athletes) is potentially associated with conditions such as chronic traumatic encephalopathy (CTE). To learn more about CTE click here.

How can I prevent a concussion?

You can reduce your risk of getting a concussion by taking some basic safety precautions. This includes:

  • Fastening your seat belt whenever you’re travelling in a car.
  • Making sure children are secured in age-appropriate safety seats. Children aged under 7 years are generally not permitted to sit in the front seat. Check with your State Government for more information.
  • Taking action to prevent falls such as avoiding standing on unstable surfaces, removing or securing small area rugs, improving lighting, and installing handrails.
  • Enforcing rules and policies that penalise head contact, rough play, or impact with the ground in contact sports at all levels of play.
  • Taking time to recover from injuries.


Learn more about concussion.

Connectivity offers a range of free short online courses on concussion.

click here to enrol in one of our FREE online courses

Disclaimer: This website does not offer medical advice for individuals. Always be guided by your medical practitioner.


What is Persistent-Post Concussion Symptoms (PPCS)?

Persistent Post-Concussion Symptoms is when the symptoms of concussion continue to affect the patient for months or even years following their injury. It is thought that PPCS is more likely to occur in those who have suffered from multiple concussions and there are a range of other risk factors that may increase the likelihood of PPCS.1

For more information on Persistent Post-Concussion Symptoms download our Fact Sheet here.


Committee on Sports-Related Concussions in Youth; Board on Children, Youth, and Families; Institute of Medicine; National Research Council; Graham R, Rivara FP, Ford MA, et al., editors. Sports-Related Concussions in Youth: Improving the Science, Changing the Culture. Washington (DC): National Academies Press (US); 2014 Feb 4. 4, Treatment and Management of Prolonged Symptoms and Post-Concussion Syndrome. Available from: https://www.ncbi.nlm.nih.gov/books/NBK185342/

What is Chronic Traumatic Encephalopathy?

Chronic Traumatic Encephalopathy is a neurodegenerative disease that is observed in people who have suffered one or usually multiple TBI, including mild TBI or concussion. Symptoms may not show for years after the injury and the disease can only be conclusively diagnosed post-mortem. In CTE a protein called hyper-phosphorylated tau forms in specific structures in certain regions of the brain. Symptoms include altered mood and behaviours, aggression, depression and control problems. These symptoms may develop into progressive dementia.



  1. Patricios JSSchneider KJDvorak J, et al Consensus statement on concussion in sport: the 6th International Conference on Concussion in Sport–Amsterdam, October 2022
  2. Scopaz KA, Hatzenbuehler JR. Risk modifiers for concussion and prolonged recovery. Sports Health. 2013;5(6):537-541. doi:10.1177/1941738112473059
  1. Health Direct, https://www.healthdirect.gov.au/concussion

Updated July 2023