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 severe difficulty breathing, chest pain, fainting, or signs of thyroid storm such as high fever, a very fast heartbeat, confusion, severe agitation, repeated vomiting, or collapse.
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:
A neck lump grows quickly or causes new hoarseness
You have trouble swallowing or shortness of breath when lying down
Your heartbeat becomes persistently fast or irregular
You develop fever or a severe sore throat while taking antithyroid medicine
You develop yellow skin, dark urine, or marked itching during treatment
3
Does any of this apply?
Book an appointment
Arrange a routine medical appointment if you develop a persistent fast or irregular heartbeat, unexplained weight loss, shaking, heat intolerance, neck swelling, or symptoms that could suggest an overactive thyroid.
Every sign above is quoted from the sofidex article on Toxic nodular goiter. If you are not sure, err upward — it is always reasonable to be checked.