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
Get emergency medical help now if the foreskin is trapped behind the penis head and will not move forward.
Call emergency services or go to an emergency department immediately if there is:
Blue, black, very pale, or rapidly darkening skin
Severe or increasing pain
Numbness or loss of sensation
Inability to pass urine
Rapidly increasing swelling
A significant injury or heavy bleeding
These signs may mean that blood flow or urinary function is affected.
However, their absence does not make a trapped foreskin safe to monitor at home.
Routine follow-up is appropriate after the foreskin has been successfully returned and the emergency has passed.
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
Do not wait to see whether the swelling goes down on its own.
3
Does any of this apply?
Book an appointment
Arrange a non-emergency appointment if swelling does not continue to improve, there are sores or discharge, the foreskin remains unusually tight, or paraphimosis happens again.
Every sign above is quoted from the sofidex article on Paraphimosis. If you are not sure, err upward — it is always reasonable to be checked.