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
Seek urgent or emergency help for:
Severe difficulty breathing, gasping, or blue or grey lips
New confusion, collapse, or difficulty waking
A seizure or a stiff neck with severe illness
Very little or no urine, severe weakness, or cold, blotchy skin
Rapidly spreading skin discoloration or severe pain out of proportion
Signs of a severe allergic reaction after medicine, such as facial swelling or breathing difficulty
These symptoms can occur with sepsis or another serious problem.
Use your local emergency number rather than waiting for a routine appointment.
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 prompt medical assessment if symptoms improve and then clearly worsen, or if you develop a new fever, increasing pain, spreading redness, pus, breathing symptoms, or signs of dehydration.
Contact a healthcare service promptly if you have possible infection symptoms and a weakened immune system, are receiving cancer treatment, have recently had surgery, or have an implanted medical device.
Fever in a baby younger than 3 months also needs urgent medical assessment.
And for anyone, someone who:
has a fever with a stiff neck, a rash that does not fade under pressure, or severe headache
has a wound that is hot, spreading red, or leaking pus
Every sign above is quoted from the sofidex article on Secondary infections. If you are not sure, err upward — it is always reasonable to be checked.