Signs and symptoms of concussion in adults, and when to get help

Concussion is a type of brain injury, usually caused by a knock to the head or a forceful jolt to the body. Most concussions are not serious. The difficulty is that the early signs can look very similar to a more serious injury, and nobody can tell the difference just by looking. That is why the warning signs come first on this page.

When should you call 999 or go to A&E after a head injury?

The NHS advises calling 999 if someone has hit their head and:

• has been knocked out and has not woken up
• cannot stay awake or keep their eyes open
• has a fit (seizure)
• has fallen from a height of more than 1 metre or 5 stairs
• has problems with their vision or hearing
• has a black eye, but did not hit their eye
• has clear fluid coming from their ears or nose
• is bleeding from their ears or has bruising behind their ears
• has new numbness or weakness in any part of their body
• has problems with walking, balance, understanding, speaking or writing
• hit their head at high speed, such as in a road accident
• has a head wound with something inside it, or a dent in their head
• has changed behaviour, such as being more irritable or distracted, or losing interest in things around them

NHS inform adds more reasons to go straight to A&E, including getting more drowsy, a severe headache or one that is getting worse, repeated vomiting, severe neck pain, and taking blood-thinning medicine such as warfarin.

Use NHS 111 if the person is being sick, feels dizzy, takes medicine that thins the blood, was drinking alcohol or taking drugs when they were hurt, or has any other symptom you are worried about. If you are told to go to A&E, do not drive yourself.

What are the common signs and symptoms of concussion?

Concussion shows up in two ways: what other people notice, and what the injured person feels.

Signs other people may notice. NHS inform says someone with concussion may:

• be confused or have a blank expression
• take an unusually long time to answer questions
• struggle to balance
• laugh or cry without explanation
• act out of character, such as being unusually irritable
• struggle to remember events before or after the injury

Symptoms the person may feel.

• a headache
• dizziness
• feeling sick
• feeling stunned or dazed
• problems with their sight, such as blurred vision or "seeing stars"

Over the following days, other symptoms can appear. NICE's written advice for adults lists problems concentrating, problems with memory, tiredness, irritability, lack of appetite and problems sleeping, which should disappear within 2 weeks.

Two points catch people out. First, most people with concussion are not knocked out: NHS inform says only 10% of concussions involve someone losing consciousness. Second, symptoms can be delayed. It can take up to 48 hours for them to appear, and Headway notes they may not show for several hours or even days.

How do you know if you have a concussion?

This is the question most people want answered, and the honest answer is uncomfortable: there is no quick test that settles it. NHS inform states that there is no test that can rule out concussion, and advises against diagnosing it without speaking to a healthcare professional.

Online checklists and pitch-side tools can prompt you to take symptoms seriously. They cannot rule out bleeding or a fracture. In hospital, the first job is to look for a more serious injury. NICE guidance says anyone attending an emergency department with a head injury should be assessed by a trained member of staff within 15 minutes of arrival, including whether they are at high or low risk of a significant brain injury. NHS inform says concussion is only diagnosed once other injuries have been ruled out.

If you did not need hospital, NHS inform's advice is to assume a concussion, follow a graduated recovery plan and call 111 for advice. Treating a suspected concussion as a definite one is the safer mistake.

Is a mild concussion still a brain injury?

Yes. The terms minor head injury, mild traumatic brain injury and concussion are often used interchangeably. Headway points out that the effects of a concussion can be anything but mild for the person living with them.

The reassuring part is also true. Headway says most concussions result in no long-term damage to the brain, and most people recover within days or weeks. "Mild" describes the category of injury, not how you might feel for the next fortnight.

What should you do in the first 24 hours?

For a minor head injury being looked after at home, the NHS suggests you:

• hold an ice pack wrapped in a tea towel to any swelling, for short periods
• rest and avoid stress; you do not need to stay awake if you are tired
• take paracetamol for a headache
• make sure an adult stays with you for at least the first 24 hours

And that you do not:

• go back to work until you are feeling better
• drive until you feel you have fully recovered
• play contact sports for at least 3 weeks
• drink alcohol until you are feeling better
• take sleeping pills while recovering unless a doctor advises you to

NHS inform goes further on supervision, suggesting a responsible adult monitors someone with a suspected concussion for 72 hours. If a hospital gave you written advice, follow that.

What if the symptoms do not settle?

See a GP if symptoms last more than 2 weeks, or if you are not sure whether it is safe to drive or return to work or sport. NHS inform describes symptoms lasting more than 28 days as post-concussion syndrome.

For people whose symptoms have lasted many months, hyperbaric oxygen therapy is an area of active research, not an emergency or first-line treatment. A 2025 sham-controlled trial of 47 adults, injured between 6 months and 10 years earlier, reported greater symptom improvement after 40 sessions at 1.5 ATA than after 40 sham sessions. It was small and stopped early, both groups improved, and an earlier military trial found no benefit over sham. Our head injury evidence page sets out both studies and their limits.

If that is where you are, what happens during treatment explains the hour itself, and you can see available times when you are ready.