Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Follow the discharge instructions provided by the emergency department, poison center, or treating clinician.
These instructions may include temporarily avoiding caffeine and other stimulants, staying hydrated, or arranging repeat testing.
The appropriate plan depends on the severity of the exposure and any abnormal findings.
Call emergency services for fainting, chest pain, severe breathing difficulty, a seizure, inability to wake, or signs of a dangerous heart rhythm.
These are emergency symptoms rather than issues to wait for at a routine appointment.
And for anyone, someone who:
Seek urgent medical review if symptoms return or worsen after discharge, especially persistent vomiting, increasing tremor, marked agitation, or a continuing rapid heartbeat.
Routine follow-up may be useful after a significant overdose, particularly if there were heart rhythm changes, abnormal blood tests, kidney problems, or ongoing palpitations.
A clinician can also review all sources of caffeine and check for medication or supplement interactions.
And for anyone, someone who:
The article also says
To reduce future risk, read labels and count caffeine from every source.
Avoid combining energy products, caffeine tablets, and workout supplements.
Keep caffeine-containing medicines and supplements away from children.
The FDA advises consumers to avoid pure or highly concentrated caffeine products because small measurement errors can have serious consequences.
Every sign above is quoted from the sofidex article on Caffeine overdose. If you are not sure, err upward — it is always reasonable to be checked.