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 care for:
Bleeding that is heavy, will not stop, or makes you faint or weak
Vomiting blood or passing black, tar-like, or visibly bloody stools
A sudden severe headache, confusion, weakness, difficulty speaking, or a seizure
A significant head injury, especially with a very low platelet count
Blood in the urine together with substantial bleeding elsewhere
Breathing difficulty or other signs of a severe reaction during an infusion
And for anyone, someone who:
is bleeding heavily and it will not stop with firm pressure
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 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 prompt medical advice if you develop new or increasing petechiae, unusual bruising, repeated nosebleeds, bleeding gums, or menstrual bleeding that is much heavier than usual.
You should also seek advice if bleeding continues despite firm pressure or if you are pregnant and have ITP symptoms.
If you have had your spleen removed, fever or signs of a serious infection need urgent medical assessment because infection can progress quickly.
3
Does any of this apply?
Book an appointment
Routine follow-up is appropriate when you feel well, symptoms are stable, and testing is occurring as planned.
The article also says
Contact your care team before surgery, dental extraction, or a procedure that could cause bleeding.
Every sign above is quoted from the sofidex article on Purpura hemorrhagica ITP. If you are not sure, err upward — it is always reasonable to be checked.