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
Seek emergency help for:
Green vomit, which may contain bile
Blood or material resembling coffee grounds in vomit
Severe or localised abdominal pain, a swollen abdomen, or severe chest pain
Confusion, a seizure, fainting, unusual weakness, or difficulty waking
A severe headache with a stiff neck, weakness, or other new neurological symptoms
Serious dehydration, breathing difficulty, suspected poisoning, or recent 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
Seek same-day medical advice if the child cannot keep fluids down, is passing much less urine, has worsening pain, or has an episode that is longer or different from usual.
Infants and children with diabetes, metabolic conditions, or other significant health problems may need earlier assessment.
These signs can have causes other than CVS and need prompt assessment.
And for anyone, someone who:
has abdominal pain that is severe, constant, or getting worse
is vomiting and cannot keep fluids down
3
Does any of this apply?
Book an appointment
Arrange a routine appointment if a child has repeated vomiting episodes, even if they recover fully between them.
Follow-up is also appropriate when episodes become more frequent, interfere with school, affect eating or growth, or are not responding to the existing plan.
Every sign above is quoted from the sofidex article on Childhood cyclic vomiting. If you are not sure, err upward — it is always reasonable to be checked.