Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Call emergency services for trouble breathing, fainting, severe weakness, confusion, a seizure, chest pain, or a fast or irregular heartbeat.
And for anyone, someone who:
Return for urgent medical assessment if pain is increasing, a wound is becoming more swollen or discolored, vision changes, vomiting continues, or swallowing becomes painful or difficult.
Follow-up may involve a primary care clinician, burn specialist, eye specialist, hand surgeon, kidney specialist, or gastroenterologist, depending on the injury.
Routine follow-up is important when there is a healing skin burn, ongoing pain, reduced movement, an eye injury, abnormal laboratory testing, or a swallowing injury.
Wounds should be checked for healing and infection.
People with an esophageal injury may need assessment for later narrowing if swallowing becomes difficult.
The article also says
Follow the discharge plan provided by the poison center or treatment team.
To reduce future risk, keep anti-rust products in their original labeled containers.
Store them away from food and out of reach of children.
Follow the label’s ventilation and protective-equipment instructions, and never mix the product with another cleaner.
Every sign above is quoted from the sofidex article on Anti-rust product poisoning. If you are not sure, err upward — it is always reasonable to be checked.