Concussion is a brain injury, and it can happen without losing consciousness. The guiding rule in international consensus statements is simple: if in doubt, sit them out.
Key points from mainstream guidance:
Any athlete with a suspected concussion should be removed from play and not return the same day
Symptoms include headache, dizziness, confusion, nausea, sensitivity to light or noise, and feeling “not right”
Return should follow a graded, step-by-step programme, usually starting with light activity and progressing only if symptoms do not return
Children and adolescents are generally managed more conservatively, and return to school or study comes before return to sport
Urgent signs that need emergency care: worsening headache, repeated vomiting, seizures, increasing confusion, weakness or numbness, slurred speech, or loss of consciousness.
Anyone with these after a head knock should go to hospital, not wait to see how they feel.