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 palpitations occur with:
Chest pain, pressure, or tightness
Severe trouble breathing
Fainting, collapse, or difficulty waking
New confusion, weakness, or signs of a stroke
Severe dizziness or a feeling that you may pass out
And for anyone, someone who:
has chest pain, tightness or pressure lasting more than a few minutes
Other emergency signs, for anyone
Someone who is struggling to breathe, gasping, choking, or cannot get words out
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 if a new episode does not settle, repeatedly returns during the day, or your heartbeat remains unusually fast or irregular.
You should also seek prompt advice if you have known heart disease or are pregnant and develop persistent palpitations.
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 episodes keep returning, are becoming more frequent, last more than a few minutes, or interfere with sleep or activity.
Arrange an assessment if they happen during exercise or if close relatives have had serious inherited heart problems or an unexplained sudden death.
The article also says
Do not drive yourself if you feel faint or seriously unwell.
Every sign above is quoted from the sofidex article on Heart palpitations. If you are not sure, err upward — it is always reasonable to be checked.