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
Pigmented birthmarks rarely cause an emergency.
Seek emergency care for a seizure, sudden weakness, confusion, loss of consciousness, sudden loss of vision, or a severe headache with repeated vomiting.
These symptoms do not necessarily come from a birthmark, but they need immediate evaluation.
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 a routine or prompt medical appointment if a birthmark develops:
Growth that is much faster than the person’s overall growth
A new firm or rapidly enlarging lump
A lasting change in color, shape, or surface
Persistent pain, itching, crusting, or tenderness
A sore that does not heal
Bleeding without a clear injury
New vision symptoms in someone with pigment around or in an eye
3
Does any of this apply?
Book an appointment
Follow-up should match the birthmark type and the person’s level of risk.
A small, stable mark may only need checks during routine health visits.
Larger congenital nevi, marks that are difficult to examine, or birthmarks linked to an eye or genetic condition may need specialist follow-up.
The article also says
At home, it can help to become familiar with the mark’s usual appearance.
Take occasional photographs in similar lighting, with a ruler for scale.
Avoid checking so often that normal variation causes unnecessary worry.
Every sign above is quoted from the sofidex article on Birthmarks - pigmented. If you are not sure, err upward — it is always reasonable to be checked.