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 sudden arm or hand weakness accompanied by facial drooping, speech difficulty, severe dizziness, or weakness elsewhere on one side of the body.
These may be signs of a stroke rather than an isolated ulnar nerve problem.
Emergency care is also appropriate after a major injury if the arm is badly deformed, there is an open wound, or the hand becomes cold, pale, blue, or severely swollen.
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
Seek prompt medical assessment if you develop:
Increasing hand weakness or loss of coordination
Constant numbness rather than occasional tingling
Visible shrinking of hand muscles
Fingers beginning to curl or becoming difficult to straighten
Symptoms following an elbow, wrist, or hand injury
A new lump near the wrist or elbow with nerve symptoms
3
Does any of this apply?
Book an appointment
Arrange a routine medical appointment if tingling or numbness keeps returning, lasts more than a short period, disturbs sleep, or interferes with daily activities.
Assessment is also appropriate if symptoms began after changing work, sport, equipment, or posture and do not settle after reducing pressure.
Every sign above is quoted from the sofidex article on Ulnar nerve dysfunction. If you are not sure, err upward — it is always reasonable to be checked.