Concussion is a temporary injury to the brain caused by a bump, blow or jolt to the head.

It usually only lasts up to a few days or weeks, although it sometimes needs emergency treatment and some people can have longer-lasting problems.

Signs and symptoms of concussion

Signs of a concussion usually appear within a few minutes or hours of a head injury.

But occasionally they may not be obvious for a few days, so it's important to look out for any problems in the days following a head injury.

Symptoms include:

• a headache that doesn't go away or isn't relieved with painkillers
• dizziness
• feeling sick or vomiting
• memory loss – you may not remember what happened before or after the injury
• clumsiness or trouble with balance
• unusual behaviour – you may become irritated easily or have sudden mood swings
• feeling stunned, dazed or confused
• changes in your vision – such as blurred vision, double vision or "seeing stars"
• being knocked out or struggling to stay awake

Concussion can be harder to spot in babies and young children.

One of the main things to look for is a change in their normal behaviour after a head injury, such as crying a lot, a change in their feeding or sleeping habits, or a loss of interest in people or objects.

What to do if you think you might have concussion

Treat a minor head injury at home

You don't usually need to get immediate medical advice if you only have mild symptoms that don't last long after a head injury, such as:

• a headache that goes away on its own or is relieved by painkillers
• slight dizziness
• feeling sick
• being a bit dazed

You probably don't have concussion, and can follow the advice about treating a minor head injury at home.

Call NHS 111 for advice if you're not sure if you need medical help.

When to go to hospital

Go to your nearest accident and emergency (A&E) department if you've injured your head and have:

• woken up after being knocked out
• problems with your memory
• a headache that doesn't go away
• been vomiting since the injury
• changes in your behaviour, such as becoming more irritable
• had an operation on your brain in the past or are taking blood-thinning medicine such as warfarin
• been drinking alcohol or taking recreational drugs

In these cases, you should be checked by a health professional trained in assessing head injuries. They'll decide if you need a brain scan to rule out a serious brain injury.

When to call 999

Call 999 for an ambulance if someone has injured their head and has:

• been knocked out and hasn't woken up
• difficulty staying awake
• problems with understanding, speaking, writing, walking or balance
• numbness or weakness in part of their body
• problems with their vision
• clear fluid coming from their ears or nose
• bleeding from their ears or bruising behind one or both ears
• a black eye with no obvious damage around the eyes
• a fit (seizure)
• hit their head in a serious accident, such as a car crash

Also call for an ambulance if someone needs to go to hospital but you can't get them there safely.

Recovering from concussion

If you're diagnosed with concussion in hospital, you'll be able to go home when any serious brain injury has been ruled out and you're starting to feel better.

Most people feel back to normal within a few days or weeks of going home. But some people, especially children, can take longer to recover.

Things you can do to help your recovery include:

• getting plenty of rest and avoiding stressful situations
• asking someone to stay with you for the first 48 hours so they can look out for problems such as changes in your behaviour or difficulty concentrating or understanding
• taking paracetamol or ibuprofen if you have a headache – don't use aspirin because it could cause your injury to bleed
• avoiding alcohol
• when you're feeling better, gradually increasing how much activity you do each day – do as much as you can without your symptoms coming back
• don't return to things like work, college, school, driving or riding a bike until you feel you've recovered
• avoiding sports or strenuous exercise for at least a week, and avoiding contact sports for at least 3 weeks

Speak to your GP if you still have symptoms after 2 weeks or you're unsure about returning to activities such as work or sports.

Get medical help straight away if you develop any symptoms that mean you should go to hospital or call 999.

After effects of concussion

In some people, concussion symptoms can last a few months or more. This is known as post-concussion syndrome.

Possible symptoms include:

• headaches
• dizziness
• problems with memory or concentration
• unsteadiness
• depression, anxiety and changes in behaviour

See your GP if you still have symptoms after 3 months. They may be able to recommend treatments for some of the symptoms, or they may refer you to a specialist.

The charity Headway has a leaflet on minor head injury and concussion (PDF, 303kb) that you might find useful if you're having long-term problems.

Preventing concussion

There's no guaranteed way to prevent concussion, but there are some simple things you can do that may reduce your risk of a head injury.

These include:

• wearing the recommended equipment when taking part in a contact sport, such as rugby or boxing
• making sure any contact sport you or your child are taking part in is supervised by a properly qualified and trained person
• wearing a seatbelt when driving
• wearing a helmet when riding a motorcycle, bicycle or horse

It's important to avoid head injuries as repeated concussions or blows to the head have been linked to serious problems, including a brain condition called chronic traumatic encephalopathy.

Read more about how to prevent head injuries.