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
Call emergency services for a headache that:
Reaches maximum intensity within seconds or a minute
Starts with new weakness, facial drooping, confusion, fainting, seizure, or major speech difficulty
Follows a significant head injury, especially with vomiting or increasing drowsiness
Occurs with fever, a stiff neck, a new rash, confusion, or severe illness
Comes with sudden loss of vision or a painful red eye
Begins during pregnancy or soon after childbirth and is sudden, severe, or accompanied by vision changes or high blood pressure
And for anyone, someone who:
has sudden weakness or drooping on one side of the face or body, slurred speech, or sudden confusion
has had a seizure that will not stop, or does not wake up afterwards
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 is unconscious, or cannot be woken
Someone who is bleeding heavily and it will not stop with firm pressure
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
Seek prompt medical assessment for a new headache with cancer, a weakened immune system, unexplained weight loss, or symptoms such as persistent vomiting.
A new headache after age 50, pain triggered by coughing or exertion, or a major change from an established pattern also needs assessment.
And for anyone, someone who:
has a fever with a stiff neck, a rash that does not fade under pressure, or severe headache
is vomiting and cannot keep fluids down
has a new severe headache unlike any they have had before
3
Does any of this apply?
Book an appointment
Arrange routine follow-up if headaches are becoming more frequent, regularly interfere with daily life, wake you repeatedly from sleep, or require increasing amounts of medicine.
New or changing aura symptoms should also be reviewed.
Every sign above is quoted from the sofidex article on Headaches/migraines. If you are not sure, err upward — it is always reasonable to be checked.