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
Contact emergency services or a poison centre immediately.
Call emergency services now for:
Trouble breathing, severe coughing, wheezing, or chest tightness
Blue-grey lips or skin, confusion, fainting, or collapse
Severe throat swelling, drooling, or inability to swallow
Vomiting blood or severe chest or abdominal pain
Any nitric acid swallowed
Any splash into the eye
A large, deep, or very painful skin burn
Routine follow-up is different from emergency care.
And for anyone, someone who:
you believe has taken an overdose or swallowed something poisonous
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
2
Is any of this happening?
Be seen today
Treat suspected swallowing, eye exposure, or significant inhalation as urgent.
Do not wait for symptoms to develop after a substantial fume exposure.
Begin water rinsing immediately after skin or eye contact while help is being arranged.
Do not delay rinsing to make a phone call.
3
Does any of this apply?
Book an appointment
Arrange follow-up if a treated burn is not healing, redness or swelling is increasing, or you develop a continuing cough, breathlessness with activity, painful swallowing, food sticking, repeated vomiting, or unintended weight loss.
Every sign above is quoted from the sofidex article on Nitric acid poisoning. If you are not sure, err upward — it is always reasonable to be checked.