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 for trouble breathing, fainting, confusion, inability to stay awake, blue or gray lips, or other signs of severe illness.
These symptoms are not typical of uncomplicated mastitis.
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
Seek urgent same-day medical care for rapidly increasing redness or swelling, severe pain, pus, a new soft or fluid-filled lump, persistent fever, or worsening illness.
People with weakened immune defenses, poorly controlled diabetes, a recent breast operation, or an implant should seek advice promptly.
And for anyone, someone who:
has a fever with a stiff neck, a rash that does not fade under pressure, or severe headache
has a wound that is hot, spreading red, or leaking pus
3
Does any of this apply?
Book an appointment
Arrange routine follow-up if:
A lump remains after pain and redness improve
Mastitis keeps returning in the same location
Symptoms occur when you are not breastfeeding
You need help with latch, pumping, oversupply, or weaning
You have ongoing nipple discharge, skin changes, or breast pain
The article also says
Contact the treating clinician if symptoms are not clearly improving within about 24 to 48 hours after starting the recommended plan.
A repeat examination, culture, ultrasound, or change in treatment may be needed.
Every sign above is quoted from the sofidex article on Breast infection. If you are not sure, err upward — it is always reasonable to be checked.