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 or go to an emergency department if symptoms spread quickly or there is severe pain, rapidly increasing swelling, blisters, crackling beneath the skin, fever with confusion, faintness, rapid breathing, or a fast heartbeat.
Sudden severe abdominal pain, persistent vomiting, or a swollen abdomen also needs emergency assessment because internal blood flow may be blocked.
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
Suspected gangrene needs urgent medical assessment.
Do not wait for skin to turn black, because blackening can be a late sign.
Seek urgent same-day medical help for:
A new wound with worsening pain, swelling, discharge, smell, or colour change
Skin that becomes cold, pale, blue, purple, brown, or black
Sudden numbness or loss of feeling near a wound
A worsening foot ulcer, especially with diabetes or poor circulation
Contact the treating service sooner if healing slows or new skin damage appears.
3
Does any of this apply?
Book an appointment
After treatment, attend routine wound, vascular, diabetes, and rehabilitation appointments.
Every sign above is quoted from the sofidex article on Gangrene. If you are not sure, err upward — it is always reasonable to be checked.