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
Get urgent or emergency help if you cannot pass urine despite a painful, full bladder, have heavy urinary bleeding or blood clots, feel faint, or are seriously unwell with possible infection.
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 prompt medical advice if you have:
New or visible blood in your urine
Pain or burning that is different from your usual symptoms
Fever, chills, vomiting, or pain in your side or back
New difficulty emptying your bladder
A major or unexplained change in your urinary pattern
3
Does any of this apply?
Book an appointment
Arrange a routine medical appointment if bladder pain, urgency, or frequent urination lasts several weeks, keeps returning, or affects sleep and daily activities.
These symptoms have several possible causes, so an assessment is needed rather than assuming they are interstitial cystitis.
These are not routine features of an interstitial cystitis flare.
Every sign above is quoted from the sofidex article on Interstitial cystitis. If you are not sure, err upward — it is always reasonable to be checked.