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 now if your child has a rash and:
is struggling to breathe or has swelling of the lips, tongue, or throat
is very difficult to wake, confused, floppy, or having a seizure
has blue, grey, unusually pale, or blotchy skin
has a rapidly spreading red or purple rash that does not fade under pressure
has widespread blistering or peeling with mouth, eye, or genital sores
And for anyone, someone who:
has lips or skin that look pale, blue, grey or blotchy
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 you believe has taken an overdose or swallowed something poisonous
2
Is any of this happening?
Be seen today
Seek urgent same-day medical care for a non-blanching rash, especially with fever or if your child seems unwell.
Do not wait for every possible symptom to appear.
A baby younger than 3 months with a temperature of 38°C or higher needs urgent medical assessment.
Also get same-day advice if the rash is painful, hot, rapidly spreading, near the eye, or accompanied by poor feeding, repeated vomiting, reduced urination, or unusual sleepiness.
Contact a clinician promptly if your child has fever, cough, runny nose, sore red eyes, and a spreading rash, particularly after possible measles exposure.
Call before attending because measles spreads easily.
Arrange review sooner if there are signs of infection, such as increasing pain, warmth, swelling, pus, or crusting.
And for anyone, someone who:
has a fever with a stiff neck, a rash that does not fade under pressure, or severe headache
3
Does any of this apply?
Book an appointment
Book a routine appointment if the rash persists, repeatedly returns, disrupts sleep, or does not improve with suitable skin care.
Every sign above is quoted from the sofidex article on Rashes in babies and children. If you are not sure, err upward — it is always reasonable to be checked.