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 if twitching occurs with:
Sudden facial drooping, one-sided weakness, or trouble speaking
Difficulty breathing or swallowing
Loss of consciousness or repeated whole-body jerking without recovery
A severe, sudden headache with weakness, confusion, or vision loss
These symptoms need emergency assessment and should not be watched at home.
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 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 urgent, same-day medical advice if twitching is accompanied by new muscle weakness, numbness, difficulty walking, or marked stiffness.
You should also seek urgent advice if widespread twitching begins with fever, agitation, or confusion after starting or changing a medicine.
3
Does any of this apply?
Book an appointment
Book a routine appointment if the twitching lasts longer than about two weeks, keeps returning, spreads to several areas, or interferes with sleep or daily activities.
An eyelid twitch should also be checked if the eye closes completely, the eyelid droops, or the eye becomes red, swollen, painful, or produces discharge.
Every sign above is quoted from the sofidex article on Twitching eyes and muscles. If you are not sure, err upward — it is always reasonable to be checked.