Concussion is a temporary disturbance of brain function caused by a blow to the head or jaw, or by a fall or sudden shaking of the head. It may cause a brief loss of consciousness, but most people with concussion never black out. Because the brain can swell or bleed after an injury that initially looks mild, anyone with suspected concussion should be watched carefully and assessed by a medical professional.
Symptoms of Concussion
- Loss of consciousness, even briefly
- Memory loss around the event
- Headache or dizziness
- Blurred vision or sensitivity to light
- Nausea or vomiting
- Irrational or unusual behaviour, or being easily upset
- Poor balance or coordination
Symptoms may appear over hours rather than immediately.
Concussion First Aid Steps
- Stop activity at once. Anyone with suspected concussion in sport or at work must stop and not return to that day’s activity.
- Support the head and neck if there was a significant impact, and check for spinal injury before moving them.
- Rest in a quiet place. Sit or lie with the head and shoulders slightly raised, and reassure them.
- Check DRABC and monitor. Note alertness, speech and vomiting. See vital signs observations.
- Arrange medical assessment and transport to hospital if there is any loss of consciousness, worsening symptoms or doubt.
- Do not leave the person alone and do not let them drive.
When Concussion Becomes an Emergency
Call the ambulance if the person has a worsening headache, repeated vomiting, a seizure, increasing drowsiness, slurred speech, weakness or paralysis, unequal pupils, clear fluid or blood from the nose or ears or a decreasing level of alertness. These signs may indicate bleeding or swelling inside the skull, as described in our cerebral compression guide.
Medicines and Recovery
Avoid alcohol and aspirin. Do not give pain relief for a headache in a person who has been unconscious in the last week unless a doctor has assessed them. Recovery usually takes days to a few weeks. Rest, gradual return to normal activity and sleep are important, and return to sport and work should follow medical clearance and a stepwise plan.
Concussion in Children and Workers
Children may be irritable, tearful or unusually quiet rather than complaining of a headache. Workplaces where falls, struck-by hazards or vehicle incidents occur should have a head injury response plan, and supervisors should know that anyone with possible concussion needs assessment before going back to safety-critical tasks such as driving or working at height.
Why Concussion Needs Careful Monitoring
Concussion is usually mild, but it sits on a spectrum with more serious brain injury. In the hours after the incident a small bleed can expand slowly, which is why a person who seems fine at first can become drowsy later. Writing down what happened, the time, the symptoms and any changes gives doctors valuable information, and a responsible adult should stay with the person overnight. Never let someone with suspected concussion return to play, drive or operate machinery until they have been medically cleared.
Frequently Asked Questions
Can you have concussion without being knocked out?
Yes. Most people with concussion remain conscious.
Is it safe to sleep after concussion?
Sleep is part of recovery, but follow medical advice on monitoring, especially in the first hours.
References and Further Reading
- NHS, Head injury and concussion
- American Heart Association and American Red Cross, Guidelines for First Aid
Last updated: October 2026
Prepared by: EHS Guidelines Editorial Team
This article is general educational information and is not a substitute for accredited first aid training or professional medical care. In an emergency, call your local emergency number immediately. Emergency numbers, medicines and protocols differ between countries, so follow local guidance.
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