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 for sudden or severe breathlessness, especially if you cannot speak in full sentences or breathe comfortably at rest.
Do not drive yourself.
Other emergency warning signs include:
Pink, blood-tinged or very frothy sputum
Blue or grey lips or skin
New confusion, severe drowsiness, collapse or fainting
Chest pain, heavy pressure or symptoms suggesting a heart attack
Severe breathing difficulty with sweating or clammy skin
Follow an existing emergency plan if you have one.
Routine appointments are not a substitute for emergency care when severe symptoms appear.
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 urgent same-day medical advice for new or steadily worsening breathlessness, increasing leg swelling, waking repeatedly because you cannot breathe, or a rapid weight increase beyond the limit in your care plan.
A lower-than-usual oxygen reading also needs prompt advice if you have been told to monitor it.
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
Routine follow-up is appropriate when you are stable after treatment or need to review gradual changes in exercise tolerance, medicines or home monitoring.
The article also says
While waiting for help, sit upright if that makes breathing easier.
Every sign above is quoted from the sofidex article on Pulmonary edema. If you are not sure, err upward — it is always reasonable to be checked.