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In this series:Head injuries

Concussion is a mild traumatic brain injury that can happen after a blow to the head or a sudden, severe jolt.

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What is concussion?

Concussion is an injury to the brain due to head trauma. It is very common. It has been estimated that there are 1 million attendances at accident and emergency departments in the UK every year due to head injuries and, off these, 9 out of 10 people have a minor head injury or concussion.

Concussion can happen after a blow to the head or a fall on to the head. It can also happen if the head is jolted very suddenly - for example, coming to a sudden halt in a car accident.

The blow or sudden jolt causes the brain to move within the skull. This temporarily interferes with the electrical signals inside the brain and has other effects, including the release of chemicals that interfere with the way the brain normally works. It is thought that in some people with concussion there may also be microscopic damage to the very smallest blood vessels in the brain.

Concussion causes

The most common causes of concussion are falling (especially from a height), road traffic accidents and accidents whilst playing sports such as football, rugby, American football, skiing, boxing and cycling.

Concussion is also known by other terms: minor head injury, minor brain injury and minor traumatic brain injury.

Concussion and sport

Concussion is a particular issue in sport, especially contact sports. Not only is it common but, if the concussion has not completely settled, having another concussion and a serious brain injury is much more likely. This is partly because the brain is more vulnerable after the first concussion, but also because being temporarily slower to react and having reduced co-ordination means a further blow is more likely.

With increased understanding of the nature of concussion, many sports now have a concussion protocol in place to reduce the risk of repeated concussions. Experts also recommend that adult, child and adolescent athletes with concussions not return to play on the same day as the injury.

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Concussion symptoms

IAfter a head injury, any of the following signs and symptoms mean that concussion is possible:

  • Headache - this is very common with concussion.

  • Blurred vision or 'seeing stars'.

  • Feeling sick (nausea).

  • Feeling dizzy.

  • Feeling in a fog.

  • Transient memory loss - not being able to remember what happened in the time (up to 24 hours) before the head injury.

  • Cognitive impairment - this means not thinking straight, so taking longer to make a decision or not being able to concentrate properly.

  • Feeling emotional.

Some symptoms of concussion don't appear immediately - for example:

  • Disturbed sleep - either being extra sleepy or not being able to sleep properly.

  • Feeling tired.

  • Feeling irritable and grumpy.

Concussion symptoms in others

If you are with someone who has hit their head and they are not conscious or responding and are lying motionless call emergency services for an ambulance.

See the separate leaflet called Head Injuries for more information.

The way a person behaves after hitting their head might indicate that they have a concussion. For example, they may:

  • Be slow to get up.

  • Be unsteady on their feet.

  • Fall over.

  • Walk with their legs wide apart or just appear not to be co-ordinated.

  • Appear dazed, with a blank or vacant look.

  • Be confused and not aware of where they are or what they have been doing.

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Concussion symptoms in a toddler or baby

If your child has hit their head and you are worried they might have concussion seek medical advice.

Children often fall and bang their heads, especially toddlers. A baby is less likely to hit their head as they can't walk and therefore don't topple over; if a baby has a minor head injury the possibility of it not being accidental has to be considered.

An infant with concussion will have similar symptoms to an adult but will not be able to tell anyone about them. Instead they may be a bit grumpy and sleepier than normal - it is common for them to want to sleep for a while after a bang to the head. This is quite normal but they should wake up completely after a nap. If they appear drowsy then they should be woken up after an hour or so.

See below for concussion red flag symptoms in children.

Emergency symptoms: when to see a doctor

Anyone who has had a head injury, however minor, does need monitoring for the first couple of days. This is because what might at first have seemed to be just symptoms of concussion could also be symptoms of a more serious problem, such as bleeding into or around the brain.

Red flag symptoms mean there may be something more serious happening. If you or someone you are looking after has had a concussion but then develops any of the following red flag symptoms you should seek immediate medical help.

  • Drowsiness or being unable to wake up.

  • A headache that is getting worse despite painkillers.

  • Confusion, behaving strangely or any having problems speaking or being understood.

  • Weakness or tingling in an arm or leg.

  • Collapse or having a seizure - shaking or twitching.

  • Being sick (vomiting).

  • Amnesia lasting more than a few minutes.

Red flag symptoms in children

The symptoms above are still important in children but may be difficult to spot due to the child's age, so additional red flags in infants and children are that they:

  • Will not stop crying.

  • Will not eat or breastfeed.

  • Are not interested in anything around them.

  • Are irritable and won't settle.

  • Behaviour has changed.

See the separate leaflet called Head Injuries for more information.

Concussion treatment

Most people make a quick recovery from concussion without any specific treatment.

Having lots of rest in the first few days and taking a day or two off work or school may be helpful and might speed up recovery.

Physical rest

  • Rest your body but don't be afraid to do some gentle exercise, building up gradually. If any of your symptoms return, ease back.

  • Have lots of sleep - take naps during the first few days if you feel tired.

  • Do not take part in contact sports, unless advised otherwise by a specific "sports medicine" doctor, until you have felt back to normal for at least three weeks.

Mental rest

Resting your brain can be harder than resting your body. Here are some suggestions:

  • Try to avoid reading or using a computer or other screen.

  • Avoid stressful situations if possible.

  • If what you are doing seems to be making your symptoms worse then stop and try again the next day.

Note: do not drive until you feel you have completely recovered. .

Concussion recovery

How long does it take to recover from concussion?

Most people with concussion recover quickly and completely within a few days or even quicker. However in some people it takes longer for the brain cells to go completely back to normal. Unfortunately it is not possible at the moment to tell who will recover quickly and who won't. If your concussion symptoms are lasting longer than a couple of weeks this is called post-concussion syndrome and you should see your doctor. See the separate leaflet called Post-concussion Syndrome for more information.

Although concussion is not thought to have permanent effects on the brain, having repeated episodes of concussion may cause permanent damage. It has been recognised for many years that repeated minor brain injury from boxing can cause a form of dementia called chronic traumatic encephalopathy. There also appears to be an increased risk of Alzheimer's disease and Parkinson's disease following minor head injury.

Concussion prevention

Anything that reduces the risk of someone hitting their head in the first place can help prevent a concussion. You can reduce the risk of concussion by:

  • Wearing a seatbelt in a car.

  • Wearing a helmet when riding a bike, motorbike or horse, skiing or snowboarding.

  • Using a mouthguard in contact sports to protect the jaw and teeth.

  • Installing safety gates and guards to protect children.

Further reading and references

Article history

The information on this page is written and peer reviewed by qualified clinicians.

  • Next review due: 30 Apr 2028
  • 2 May 2023 | Latest version

    Last updated by

    Dr Pippa Vincent, MRCGP

    Peer reviewed by

    Dr Colin Tidy, MRCGP
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