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 now if facial swelling comes with:
Trouble breathing, swallowing, or speaking
Swelling of the tongue, mouth, or throat
Wheezing, faintness, confusion, or blue-grey lips
Rapidly worsening swelling after food, medicine, or an insect sting
These can be signs of anaphylaxis, a severe allergic reaction.
It can happen without a rash.
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 care for swelling around an eye with redness, fever, severe pain, pain when moving the eye, reduced vision, or an eye that appears pushed forward.
Infection around the eye can threaten vision and needs prompt treatment.
You also need same-day assessment if swelling is rapidly spreading, follows a serious injury, or occurs with fever and severe dental pain.
Difficulty opening your mouth, swallowing saliva, or swelling under the jaw requires urgent care.
Arrange an appointment sooner if you also develop ankle swelling, unusual urine changes, unexplained weight change, or ongoing fatigue.
And for anyone, someone who:
is getting rapidly more short of breath, or has gained several pounds in a few days with swelling
3
Does any of this apply?
Book an appointment
Book a routine appointment if swelling has no clear cause, keeps returning, or does not begin to improve within a few days.
And for anyone, someone who:
has noticed a lump, a mole that has changed, or unexplained weight loss
Every sign above is quoted from the sofidex article on Facial swelling. If you are not sure, err upward — it is always reasonable to be checked.