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
Elsewhere, contact your local poison centre or emergency advice service.
Call emergency services immediately if the person:
Has a seizure, collapses, or faints
Is difficult to wake or cannot respond normally
Has trouble breathing or develops blue or grey lips
Has severe confusion, hallucinations, or uncontrollable agitation
Has a very fast or irregular heartbeat
Develops a high temperature with hot, dry skin
May have taken dimenhydrinate intentionally
May have taken several medicines or an unknown amount
And for anyone, someone who:
is unconscious, or cannot be woken
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 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 any suspected dimenhydrinate overdose as urgent, even if the person currently feels well.
In the United States, call Poison Control at 1-800-222-1222 .
New fainting, worsening confusion, reduced urination, severe muscle pain, or breathing difficulty after discharge requires urgent reassessment.
3
Does any of this apply?
Book an appointment
Routine follow-up may be recommended after recovery to review kidney or muscle test results, ongoing symptoms, medication safety, or mental health needs.
And for anyone, someone who:
is having side effects from a medicine, or is struggling to take it as prescribed
The article also says
Do not leave a severely confused or sleepy person alone.
If they are unconscious but breathing, place them on their side if you can do so safely.
Do not put anything in their mouth during a seizure.
Every sign above is quoted from the sofidex article on Dimenhydrinate overdose. If you are not sure, err upward — it is always reasonable to be checked.