Concussion

A concussion, also known as a mild traumatic brain injury (mTBI), is a head injury that temporarily affects brain functioning. Symptoms may include headache, dizziness, difficulty with thinking and concentration, sleep disturbances, a brief period of memory loss, brief loss of consciousness, problems with balance, nausea, blurred vision, and mood changes. Concussion should be suspected if a person hits their head and experiences any of the symptoms of concussion. Signs and symptoms of a concussion usually occur within minutes to hours of the injury, usually within 72 hours. However, symptoms may be delayed by 1–2 days after the accident. It is not unusual for symptoms to last 2 weeks in adults and 4 weeks in children. Symptoms of a concussion may make it difficult to return to work, school, sports or prior level of functioning, with disability usually lasting days to weeks. Fewer than 10% of sports-related concussions among children are associated with loss of consciousness.

Wikipedia. CC BY-SA 4.0. Updated Jun 5, 2026.