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 now if chills occur with:
Severe difficulty breathing, blue or gray lips, or chest pressure
New confusion, fainting, a seizure, or difficulty waking
A stiff neck with a severe headache or a rapidly spreading rash
Signs of severe cold exposure, such as slurred speech or poor coordination
A temperature below 35°C or 95°F after cold exposure
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 same-day medical care if you have chills with a fever and painful urination, side or back pain, a worsening cough, repeated vomiting, severe weakness, or a painful spreading skin infection.
Also seek prompt advice if you are pregnant or have a weakened immune system because of chemotherapy, a transplant, certain medicines, or an immune condition.
Tell clinical staff immediately if chills begin during a transfusion or intravenous treatment.
For a baby younger than 3 months, a temperature of 38°C or 100.4°F or higher needs urgent medical assessment.
3
Does any of this apply?
Book an appointment
Book a routine appointment if chills continue for several days, keep returning without an obvious reason, or occur with ongoing night sweats, unexplained weight loss, or persistent tiredness.
Every sign above is quoted from the sofidex article on Chills. If you are not sure, err upward — it is always reasonable to be checked.