Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
1
Is any of this happening now?
Call 911
Seek emergency help after a head injury if there is:
Increasing difficulty waking or staying awake
A worsening headache or repeated vomiting
A seizure, collapse, or prolonged loss of consciousness
New weakness, numbness, poor coordination, or slurred speech
Increasing confusion, agitation, or unusual behaviour
One pupil larger than the other or new double vision
Clear fluid or blood coming from the nose or ears
An open wound, dent in the skull, or penetrating injury
Emergency assessment is also important after a significant head injury in someone taking blood-thinning medicine or with a bleeding disorder, even if early symptoms seem mild.
And for anyone, someone who:
is bleeding heavily and it will not stop with firm pressure
Other emergency signs, for anyone
Someone who is struggling to breathe, gasping, choking, or cannot get words out
Someone who has chest pain, tightness or pressure lasting more than a few minutes
Someone who has sudden weakness or drooping on one side of the face or body, slurred speech, or sudden confusion
Someone who is unconscious, or cannot be woken
Someone who has had a seizure that will not stop, or does not wake up afterwards
Someone who has lips or skin that look pale, blue, grey or blotchy
Someone who you believe has taken an overdose or swallowed something poisonous
2
Is any of this happening?
Be seen today
Arrange prompt medical advice for ongoing headache, dizziness, memory problems, mood changes, or sleep disturbance after a head injury.
3
Does any of this apply?
Book an appointment
Routine follow-up is appropriate when symptoms are stable but are not improving, interfere with daily life, or return as activity increases.
Every sign above is quoted from the sofidex article on Traumatic brain injury. If you are not sure, err upward — it is always reasonable to be checked.