First aid · · 2 min read
Concussion: warning signs after a head injury
After a head injury, assess symptoms rather than the size of a bump. Concussion can happen without loss of consciousness. Seizures, inability to wake, new weakness or speech problems require emergency help.
Symptoms may be delayed
Headache, dizziness, nausea, light sensitivity, slowed thinking and concentration problems may develop after an injury. Behaviour changes also matter in children. Tell the clinician how the injury happened and what changed afterwards.
Changes that need assessment
Worsening consciousness, seizures, weakness, speech problems or repeated vomiting need urgent assessment. Blood-thinning medicines make seeking advice particularly important even after a seemingly minor injury.
Home observation follows risk assessment
If home care is advised, obtain clear instructions and return precautions. NHS advice recommends an adult stay for the first 24 hours. Forced wakefulness is not routinely necessary unless advised, but dangerous drowsiness needs help.
Returning to daily activities
Return to school, work, driving and sport depends on symptoms and repeat-injury risk. Do not return to play immediately after a suspected concussion. Persistent symptoms or disruption to everyday life warrant follow-up.
Your practical checklist
- Record the injury time and medicines taken.
- Arrange observation and a clear emergency care plan.
- Discuss a staged return to activity with a healthcare professional.
Questions and answers
Is loss of consciousness required?
No. Assessment considers symptoms and injury circumstances rather than that single feature.
Can an online test rule out a serious injury?
No. It cannot exclude bleeding or other dangerous head-injury complications. Warning signs need urgent in-person care.
Sources
Sources checked on 26 September 2026.