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, collapse, reduced consciousness, chest pain, or severe confusion.
Fever with marked agitation and a very fast heartbeat also needs emergency assessment, as do profound drowsiness, unusually low body temperature, and slow breathing.
Emergency care is not usually needed for an unchanged neck lump or mild, long-standing symptoms.
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:
A thyroid lump that is enlarging or feels firm
Persistent hoarseness, swallowing difficulty, or neck pressure
A sustained fast or irregular heartbeat
New or worsening eye pain, double vision, or vision changes
Significant symptoms during pregnancy or after giving birth
Fever or a severe sore throat while taking an antithyroid medicine
3
Does any of this apply?
Book an appointment
Arrange a routine appointment if you have persistent symptoms of an underactive or overactive thyroid, a new neck swelling, or a change in an existing thyroid lump.
Symptoms alone cannot confirm the cause, but blood tests and an examination can guide the next steps.
Routine follow-up is appropriate for stable symptoms, planned blood tests, medication reviews, and monitoring of a known benign nodule.
Every sign above is quoted from the sofidex article on Thyroid disorders. If you are not sure, err upward — it is always reasonable to be checked.