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 if sudden flushing occurs with trouble breathing, swelling of the lips, tongue, or throat, faintness, collapse, or widespread raised itchy patches.
These can be signs of a severe allergic reaction called anaphylaxis.
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 same-day medical advice if facial redness is painful, hot, swollen, or spreading, especially if you also have a fever or feel very unwell.
These features may suggest an infection rather than ordinary blushing.
3
Does any of this apply?
Book an appointment
Book a routine appointment if:
episodes are becoming more frequent or have no clear trigger
redness remains between episodes or your skin is painful or irritated
flushing comes with repeated diarrhoea, wheezing, severe headaches, or strong heartbeat changes
symptoms began after starting or changing a medicine or supplement
fear of blushing is affecting work, school, relationships, or social activities
The article also says
Blushing by itself is rarely an emergency.
Every sign above is quoted from the sofidex article on Blushing. If you are not sure, err upward — it is always reasonable to be checked.