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 care if double vision begins with:
Sudden severe headache
New weakness, numbness, facial drooping, or trouble speaking
Confusion, fainting, severe dizziness, or difficulty walking
Sudden loss or major reduction of vision
Fever, stiff neck, or repeated vomiting
A significant head injury
Rapidly worsening symptoms or several new neurological symptoms
And for anyone, someone who:
has sudden weakness or drooping on one side of the face or body, slurred speech, or sudden confusion
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 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 a prompt medical assessment for new double vision, a new inward eye turn, or difficulty moving an eye outward.
This applies even if covering either eye removes the second image and you have no other symptoms.
If you are over 50, new double vision with a new headache, scalp tenderness, jaw pain while chewing, or loss of vision needs urgent same-day assessment.
These symptoms can occur with inflammation of the arteries supplying the head and eyes.
Contact the treating service sooner if double vision worsens, pain develops, another eye movement becomes limited, or there is no improvement within the expected follow-up period.
A new eye turn, unusual head posture, or possible double vision in a child should be assessed promptly.
And for anyone, someone who:
has a new severe headache unlike any they have had before
3
Does any of this apply?
Book an appointment
For an established palsy, routine follow-up remains important.
Every sign above is quoted from the sofidex article on Cranial mononeuropathy VI. If you are not sure, err upward — it is always reasonable to be checked.