Mild traumatic brain injury (MTBI)

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. If you have experienced a concussion, see a doctor as soon as possible.

On this page, you can find the following information:

Key points 

  1. Most people with a concussion recover fully. Specific treatment is not often needed but you need advice around what you can do, both physically and mentally. 
  2. To help your recovery, you need rest (physical and mental) for at least 48 hours post-injury.
  3. It may take several hours (or even days) after an injury for some or all of the symptoms to appear. 
  4. Symptoms of a concussion generally improve within 2 weeks post-injury; however, this may be longer in children and adolescents (under 18 years old).
  5. It takes time for your brain to heal. Do not to return to work or sports activities until you have been cleared as safe to do so.
  6. If you return to activity before you have completely recovered, you are at greater risk of having a second concussion. Second or later concussions can be very serious.
  7. If your symptoms get worse, or you notice new symptoms, see a doctor as soon as possible.

What should I do if I think I’ve had a concussion?

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 other symptoms of concussion.

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.

What is concussion?

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 provides a useful summary of the key points to know. 

(Dr Mike Evans, 2014)

Who is at risk of concussion?

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.

What are the symptoms of a concussion?

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. 

What is the treatment for concussion?

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 through ACC to a Concussion Service may be needed.

  • ACC’s Concussion Service provides early intervention rehabilitation services for ACC clients with a mild to moderate traumatic brain injury.
  • The referral form (ACC883) can be downloaded from the ACC website.
  • Referrers are recommended to send the referral directly to the client’s nearest ACC Short Term Claims Centre.

Avoiding a second concussion

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. 

How long does concussion last for?

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. 

Self-care ­– recovery from concussion

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. 

Learn more

What is a brain injury? Brain Injury NZ
Resources for living with a brain injury Brain Injury NZ
Causes and symptoms of concussions Ministry of Health, NZ, 2014
National guidelines for sport concussion ACC, NZ, 2012
Concussions Healthline, US, 2012


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

Dr Stephen Kara

Stephen works with Axis Sports Medicine Specialists in their dedicated sports concussion clinic. His interest in concussion was generated from 15 years involvement in provincial and national rugby and has led to an education role with NZ rugby for community-based rugby and referees. 

Stephen is a subject matter expert in concussion and head injury.
Credits: Health Navigator Editorial Team. Reviewed By: Dr Stephen Kara, MBChB, FRNZCGP, Dip Sports Med, Dip Obs, MPhil (Hons) Last reviewed: 27 May 2019