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:
Fainting, severe breathlessness, confusion, or difficulty waking
Rapidly worsening pallor with extreme weakness
Severe abdominal pain with fever, repeated vomiting, or worsening jaundice
A significant blow to the abdomen followed by pain, dizziness, or faintness
Follow your emergency infection plan and seek urgent medical assessment rather than waiting for symptoms to settle.
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
A baby with worsening jaundice, poor feeding, unusual sleepiness, or breathing difficulty needs prompt assessment.
Arrange urgent or same-day advice for a sudden change in tiredness or pallor, especially during an infection or after known exposure to parvovirus B19.
These symptoms may indicate a rapid fall in hemoglobin.
And for anyone, someone who:
has a wound that is hot, spreading red, or leaking pus
3
Does any of this apply?
Book an appointment
Routine follow-up is appropriate for stable tiredness, recurring mild jaundice, abdominal fullness, or questions about exercise, pregnancy, vaccination, or family testing.
The article also says
If you have had your spleen removed, fever can be an early sign of a serious infection.
Every sign above is quoted from the sofidex article on Hereditary spherocytic anemia. If you are not sure, err upward — it is always reasonable to be checked.