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 rapid or difficult breathing accompanied by:
Blue or grey lips, face, or skin
Severe chest pain, pressure, or heaviness
Fainting, marked confusion, or difficulty waking
New weakness on one side, facial drooping, or trouble speaking
Coughing up blood
Severe breathlessness that is worsening or prevents speaking
A suspected overdose, poisoning, or serious allergic reaction
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 prompt medical assessment for a first severe episode, new breathlessness during pregnancy, breathing trouble after surgery or prolonged immobility, or symptoms accompanied by fever, wheezing, leg swelling, or an irregular heartbeat.
3
Does any of this apply?
Book an appointment
Arrange routine care if episodes recur, the cause is uncertain, or breathing symptoms are affecting sleep, work, exercise, or emotional well-being.
A previous history of panic does not mean every new breathing problem is caused by panic.
Every sign above is quoted from the sofidex article on Hyperventilation. If you are not sure, err upward — it is always reasonable to be checked.