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 nausea or vomiting occurs with:
Chest pressure or pain, shortness of breath, heavy sweating, or pain spreading to the arm, back, neck, or jaw
Sudden severe abdominal pain or a hard, swollen abdomen
Vomit containing blood, material like coffee grounds, or bright green fluid
A sudden severe headache, confusion, a stiff neck, fainting, or new weakness
Suspected poisoning or a recent serious head injury
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
Get same-day medical advice if you cannot keep fluids down or have signs of dehydration.
These include a very dry mouth, dark urine, urinating much less than usual, unusual tiredness, or dizziness when standing.
Same-day advice is also appropriate if you are pregnant and cannot drink enough, or if you have diabetes and are vomiting or have high glucose or ketone readings.
And for anyone, someone who:
is vomiting and cannot keep fluids down
3
Does any of this apply?
Book an appointment
Book a routine appointment if nausea lasts more than a few days, repeatedly returns, disrupts eating, or causes unplanned weight loss.
You should also arrange follow-up if it began after starting or changing a medicine.
Do not stop a prescribed medicine without advice.
Every sign above is quoted from the sofidex article on Feeling sick. If you are not sure, err upward — it is always reasonable to be checked.