Concussion is a mild traumatic brain injury caused by a blow or sudden movement of the head. A person does not need to lose consciousness to have a concussion. Symptoms can begin immediately or develop over the following hours.
Possible symptoms
- Headache or pressure in the head
- Dizziness, balance problems or nausea
- Confusion, memory gaps or slowed thinking
- Blurred vision or sensitivity to light and noise
- Tiredness, irritability or emotional changes
- Sleep disturbance
Emergency warning signs
Call emergency services after a head injury if the person cannot stay awake, has a seizure, develops weakness or numbness, has difficulty speaking or walking, has clear fluid or blood from the ears or nose, or has a worsening severe headache. Repeated vomiting, increasing confusion, unusual behaviour or unequal pupils also require emergency assessment.
Medical advice is especially important after significant trauma, for babies and older adults, and for anyone taking an anticoagulant or living with a bleeding disorder.
Recovery
An adult should stay with the injured person for the first 24 hours when home observation is considered safe. Sleep is allowed; there is no need to force the person to remain awake. Use only recommended pain relief and avoid alcohol, recreational drugs, driving and activities that risk another head injury.
After a short period of relative rest, gradually resume normal mental and physical activity as symptoms allow. Reduce activity if symptoms clearly worsen, then progress more slowly. Do not return to contact sport on the same day and follow a supervised graduated return-to-sport process.
Persistent symptoms
Most people improve, but headache, fatigue, dizziness or concentration problems can last longer. Seek medical review if symptoms persist beyond two to three weeks, worsen after initial improvement or interfere with school, work or daily life.
Sources
Reviewed: 28 August 2026