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 the person has:
Difficulty breathing, severe wheezing, or airway swelling
Blue or grey lips, skin, or nails
Confusion, collapse, a seizure, or trouble waking
Severe chest pain or an abnormal heartbeat
Drooling or inability to swallow
A serious eye injury or extensive chemical burn
A deliberate or potentially large ingestion
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
Contact a poison information service promptly after fertilizer is swallowed, even if there are no symptoms.
In the United States, Poison Control is available at 1-800-222-1222 .
Elsewhere, use your local poison centre or urgent medical advice service.
Seek urgent medical assessment for persistent vomiting, worsening stomach pain, ongoing coughing, eye pain after rinsing, a skin burn, unusual weakness, or symptoms that are not settling.
The article also says
Do not give anything by mouth to someone who is drowsy, having a seizure, or unable to swallow safely.
Every sign above is quoted from the sofidex article on Plant fertilizer poisoning. If you are not sure, err upward — it is always reasonable to be checked.