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 or go to an emergency department now if your baby:
Is difficult to wake, unusually floppy, or not responding normally
Has a seizure
Has trouble breathing or develops blue, grey, or very pale skin
Has a stiff body or neck with fever
Develops a red or purple rash that does not fade under pressure
Has a bulging fontanelle after a significant head injury
Has sudden weakness, unusual eye movements, or repeated forceful vomiting
If the fontanelle only becomes full during crying or while lying down, then returns to normal when your baby settles, an emergency assessment may not be needed.
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
Arrange same-day urgent medical assessment if the fontanelle stays bulging while your baby is calm and upright.
This is especially important if there is fever, repeated vomiting, poor feeding, unusual irritability, or your baby seems less alert than normal.
A baby younger than 3 months with a temperature of 38°C or higher needs urgent medical assessment, whether or not the fontanelle is bulging.
3
Does any of this apply?
Book an appointment
Book a routine appointment if it keeps happening, the shape of the head is changing, or you are unsure what you are seeing.
Every sign above is quoted from the sofidex article on Fontanelles - bulging. If you are not sure, err upward — it is always reasonable to be checked.