Mild traumatic brain injury (MTBI)

Key points about concussion

  • A concussion is a mild brain injury. It happens when a bump, blow or shake to your head or body causes your brain to shake inside your skull.
  • A concussion affects how your brain functions and may occur with or without loss of consciousness.
  • Symptoms include headache getting worse, confusion, slurred speech, double vision, being sleepy and difficult to wake and vomiting (see more below).
  • If you have experienced a concussion, see a doctor as soon as possible.
Woman sits outside with head injury having fallen off bike
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A concussion is a type of mild traumatic brain injury (mTBI). It occurs when a bump, blow or shake to your head or body causes your brain to shake inside your skull, causing your brain to be bruised in a similar way to other parts of the body. 

You don't have to get a blow directly to your head itself – impact anywhere on your body that causes your head to shake violently can lead to a concussion.

You also don't have to be knocked out to get a concussion. In fact, loss of consciousness only happens with 10% of concussions. 

The following video by Dr Mike Evans, on concussion management and return to learn, provides a useful summary of the key points to know.

(Doc Mike Evans, 2015)

If you, or someone else, has had (or may have had) a concussion, it needs to be taken seriously. See your doctor as soon as possible. 

Warning signs to watch for
The first 24 hours after having a brain injury are crucial. You should seek urgent medical help (either go to A&E or call 111 for an ambulance) if you or someone you are caring for:
  • has a headache that gets worse, that is not relieved with simple pain relief like Paracetamol
  • is very sleepy or difficult to wake
  • is confused or doesn’t recognise you
  • has fits or seizures (repeated jerking movements of arms, legs or face)
  • has strange feelings or loss of movement down one side of the body
  • slurs their speech
  • has blurred vision bad enough to stop seeing properly
  • has double vision
  • is increasingly irritable or restless
  • repeatedly vomits (more than 1 vomit for an adult, any vomit for a child)
  • complains of neck pain
  • has behavioural changes
  • passes out.
See symptoms of concussion below.

Call Healthline free on 0800 611 116 if you are unsure what to do.
Anyone who knocks their head (playing a sport or through a fight or accident) and gets up straight away, still needs to be closely watched as they may develop symptoms after the injury, usually within that day. If they show any of the danger signs above, they need to see a doctor as soon as possible. 
Likewise, anyone who is knocked out, ie, is unconsciousness and can't be woken up, even if only for a few seconds, needs to see a doctor urgently. This is to check for a skull fracture or serious brain injury.

A concussion can happen to anyone. Common events causing concussion include the following:

    • Falls. These are the most common cause of concussion overall, particularly in older adults and young children.
    • Vehicle-related collisions. Collisions involving cars, motorcycles or bicycles – and pedestrians involved in such accidents.
    • Domestic violence. This, child abuse and other assaults are common causes.
    • Sports injuries. Concussions are a common type of sports injury. Higher risk sports for concussion include contact activities such as boxing, martial arts, rugby union and rugby league. It can also occur in any sport with fast movement or balls, including cycling, equestrian activities, cricket, hockey, water polo, snow sports but can occur across all sporting activities.

Symptoms of concussion or mild traumatic brain injury (mTBI) may not appear for hours, days or until you are challenged (physically or mentally) following a head injury. 

Warning signs
The first 24 hours after having a brain injury are crucial. You should seek urgent medical help (either go to A&E or call 111 for an ambulance) if you or someone you are caring for shows any of the warning signs in the table above.

If you have had a concussion, or think you have a concussion, it needs to be taken seriously. See your doctor as soon as possible if you notice any of the following signs of concussion.

Some immediate signs of a concussion include someone who:

  • appears dazed
  • is confused
  • has poor balance and lack of coordination
  • answers questions slowly
  • runs in the wrong direction
  • forgets events that occurred before and after impact
  • vomits
  • loses consciousness – but it is important to remember that a person can have a concussion without losing consciousness
  • is seen falling to the ground like a rag doll after a hit, with no signs of trying to protect themselves in the fall
  • displays seizure-like activity.

A person complaining of the following symptoms may also have had a concussion:

  • headache
  • double or blurred vision
  • confusion
  • fatigue (tiredness) – usually more tired than they would be after the event
  • poor concentration
  • difficulty remembering things
  • sleep difficulties, either getting to sleep, waking through the night or longer sleep periods
  • emotional changes including irritability, sadness, tearful sensitivity to noise and light
  • feeling slowed down as if things around you are going faster and you cannot keep up
  • lightheaded and dizziness
  • feeling off balance, like you are on a rocking boat 

Not every sign and symptom will be present in every person and some may not appear for hours or days following a head injury.

Fortunately, these symptoms are usually temporary. But if you don't let your brain fully recover after an injury, a concussion can lead to permanent damage. 

If you get a concussion, you need to be seen by a doctor. The first 24 hours after the bump or blow are critical, as this is when serious complications are more likely to occur. It is really important you are not alone and someone monitors how you are doing.

In the first 24 hours following your concussion:

  • Rest as much as possible, but do not to go to sleep in the first 4 hours. After that, you need a normal night’s sleep at the normal time.
  • If there is any concern about the severity of the injury, it is safest on the first night to gently wake the sleeper every 2 hours and ask them to answer a simple question. If they can’t be woken normally, then get medical help urgently.
  • Avoid alcohol, sleeping pills and illegal drugs – these can hide problems that might be developing.
  • Take paracetamol if needed for headache.
  • Don’t drive a motor vehicle.
  • Avoid physical activity.

After a doctor has seen you, most people with symptoms of concussion recover without treatment, but rest is important. If your doctor has advised you to stay off work or sport, do so until you have no symptoms and your doctor says you are ready to return.

If at any point symptoms get worse, or if more serious symptoms develop (see warning signs above) see a doctor straight away. 

If your symptoms continue for more than 2 weeks, see your doctor again. For people with ongoing symptoms, referral to a Concussion Service may be needed.

If you have had a concussion, see a doctor and do NOT return to sports activities or work (where any further injury is a risk) before you have been cleared as safe to do so.

The effects of repeated concussions build up. If you get a second injury before the first one has healed properly, you can end up with a more serious injury. A second concussion can cause acute brain swelling and bleeding. This can be difficult to treat and can lead to permanent disability, even death. 

Your brain needs rest to recover from a concussion. Ignoring your symptoms and trying to “tough it out” can make symptoms worse. Recovery is faster when you rest immediately following the injury, seek medical advice and go back to your normal daily activities gradually.

Don't increase your activity level until you are cleared by a doctor to do so – it's not worth the risk.

Many adults recover from a concussion within 2 weeks. For children and teenagers (under 18 years old) recovery can take longer, averaging around 4 weeks. 

Some people have symptoms that will last longer. This is now known as persistent concussion syndrome. 

To improve your recovery, follow these rules: 

  • Physical and mental rest is advised for the first 48 hours after the injury. After this, seek advice regarding making a plan for a gradual return to normal activates.
  • Avoid anything that stimulates your brain too much – screens, loud music, noisy environments.
  • Stay off work until you are told by a doctor that you can return. Discuss a gradual return to work (reduced work hours and lighter duties) with your doctor and employer, if necessary.
  • Avoid hard physical activities, especially contact sports, for at least 3 weeks. Do not return until you have no symptoms and have been cleared by your doctor to do so. A second concussion within a short time of the first one can be disastrous.
  • Ask your family/whānau and friends for support. They may also need to get some support to understand and help you with your recovery. 

Stories from people who have had concussions.

Shontayne Hape - concussions in rugby

Shontayne Hape (NZ rugby player) talks about his experience with concussion and how to stay safe on the field.

(Sport360, AE, 2015)

What happened at Rugby?

(NZ Rugby, 2018)

Rugby Concussion 2

(NZ Rugby, 2018)

Symptoms RugbySmart

(NZ Rugby, 2018)

Rugby Concussion Stand downs

(NZ Rugby, 2018)

What is a brain injury?(external link)(external link) Brain Injury NZ
Resources for living with a brain injury(external link)(external link) Brain Injury NZ
Causes and symptoms of concussions(external link)(external link) Ministry of Health, NZ, 2014
National guidelines for sport concussion [PDF, 886 KB] ACC, NZ, 2012
Concussion – not just for adults(external link) ACC, NZ, 2019
Concussions(external link)(external link) Healthline, US, 2012



Recovery advice Whakaora Tohutohu for patients(external link)(external link) Accident Compensation Corporation (ACC), NZ, 2022 English(external link), te reo Māori(external link)
Caring for your child after their head injury(external link)(external link) Accident Compensation Corporation (ACC), NZ, 2022
Concussion – recognising the signs(external link)(external link) Flipcards, ACC, SportsSmart, 2016
Concussion(external link)(external link) Graduated return to play poster by Rugby Smart, NZ, 2019


SCAT3 Sports Concussion Assessment Tool 3rd Ed.(external link)(external link)


  1. Daneshvar DH, Baugh CM, Nowinski CJ, et al. Helmets and mouth guards – the role of personal equipment in preventing sport-related concussions(external link)(external link)Clinics in Sports Medicine, 2011;30(1):145-163.
  2. Gavett BE, Stern RA, McKee AC. Chronic traumatic encephalopathy – a potential late effect of sport-related concussive and subconcussive head trauma(external link)(external link) Clinics in Sports Medicine, 2011;30(1):179-188.(external link)
  3. Treatment and management of prolonged symptoms and post-concussion syndrome(external link)(external link) In sports-related concussions in youth – improving the science, changing the culture. Institute of Medicine National Research Council. National Academies Press, US, 2014 


concussion recognising the signs acc sportsmart

Concussion – recognising the signs(external link)

Flipcards, ACC, SportsSmart, 2016

Recovery advice Whakaora Tohutohu for patients ACC, NZ
English, te reo Māori

caring for your child after their head injury

Caring for your child after their head injury(external link)

Accident Compensation Corporation (ACC), NZ, 2022

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Credits: Healthify editorial team. Healthify is brought to you by Health Navigator Charitable Trust.

Reviewed by: Dr Stephen Kara, MBChB, FRNZCGP, Dip Sports Med, Dip Obs, MPhil (Hons)

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