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 now if numbness begins suddenly, especially on one side, or occurs with:
Facial drooping, arm or leg weakness, confusion, or trouble speaking
Sudden vision loss, severe dizziness, or difficulty walking
A sudden severe headache unlike your usual headaches
Loss of bladder or bowel control, numbness around the genitals or buttocks, or severe back pain
Rapidly increasing weakness, trouble swallowing, or difficulty breathing
Symptoms after a serious head, neck, or back injury
Stroke symptoms need emergency care even if they disappear.
A TIA can cause brief stroke-like symptoms and is also an emergency.
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
Seek same-day medical advice if numbness is new and steadily spreading, affects most of a limb, or appears with new weakness.
You should also seek prompt care for numbness with a painful blistering rash, particularly on the face, or for an unnoticed foot wound if you have diabetes or poor circulation.
3
Does any of this apply?
Book an appointment
Book a routine appointment if symptoms persist, keep returning, disturb sleep, or affect walking, balance, work, or everyday tasks.
Every sign above is quoted from the sofidex article on Numbness and tingling. If you are not sure, err upward — it is always reasonable to be checked.