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 confusion, inability to stay awake, a seizure, trouble breathing, collapse, or significant bleeding.
If there is an immediate risk of self-harm, call emergency services or a local crisis service rather than leaving the person alone.
And for anyone, someone who:
Contact the treating clinician promptly if nausea, abdominal pain, poor appetite, or unusual tiredness returns.
Seek urgent medical assessment for yellow skin or eyes, reduced urination, worsening vomiting, or new bruising.
Follow-up depends on the severity of the exposure.
Some people can leave care after acetaminophen is no longer detectable, relevant laboratory results are reassuring, and the treating team determines that antidote therapy is no longer needed.
Others require repeated blood tests or hospital monitoring until liver function is clearly improving.
Follow-up may include counseling, crisis support, medication review, and a plan for safer medicine storage.
And for anyone, someone who:
The article also says
After discharge, follow the care team’s instructions about repeat liver tests and the use of acetaminophen, alcohol, supplements, and other medicines.
Do not restart acetaminophen after an overdose unless a clinician says it is safe.
If the overdose was intentional or occurred during a period of emotional distress, a mental health and safety assessment is an important part of care.
Every sign above is quoted from the sofidex article on Acetaminophen overdose. If you are not sure, err upward — it is always reasonable to be checked.