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 with:
Severe trouble breathing, blue or grey lips, or swelling of the tongue
Unusual sleepiness, difficulty waking, confusion, or a seizure
A non-blanching rash and they appear seriously unwell
Rapidly spreading purple or bruise-like marks
Widespread blistering, peeling skin, or painful sores around the eyes or mouth
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 medical assessment the same day if your baby is under 3 months old and has a temperature of 38°C or higher.
Also seek prompt care if your child has a rash with breathing changes, poor feeding, repeated vomiting, fewer wet nappies, severe pain, or a fever and is becoming less responsive.
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
Arrange a routine appointment if the rash keeps returning, is worsening, lasts longer than expected, disrupts sleep, or does not improve with simple skin care.
A clinician should also assess yellow crusting, pus, increasing warmth, swelling, or tenderness, which can suggest infection.
Every sign above is quoted from the sofidex article on Rash - child under 2 years. If you are not sure, err upward — it is always reasonable to be checked.