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 immediately if a sudden metallic taste occurs with:
Facial droop, one-sided weakness, or difficulty speaking
Severe confusion, loss of balance, or a sudden severe headache
Swelling of the lips, tongue, mouth, or throat
Trouble breathing or swallowing
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 same-day medical or dental care if you have spreading facial or mouth swelling, fever with severe tooth pain, or difficulty drinking.
Get prompt advice after a suspected poisoning or significant chemical exposure.
In the United States, Poison Control can be reached at 1-800-222-1222.
3
Does any of this apply?
Book an appointment
Book a routine appointment if the taste persists, keeps returning, or makes it difficult to eat.
You should also arrange an assessment if you have unexplained weight loss, ongoing dry mouth, mouth sores, bleeding gums, or a new taste change after starting a medicine.
Every sign above is quoted from the sofidex article on Metallic taste. If you are not sure, err upward — it is always reasonable to be checked.