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 information service or emergency service.
Call emergency services now if the person:
Cannot be awakened, collapses, or has a seizure
Has slow, difficult, or irregular breathing
Has blue, gray, or unusually pale lips or skin
Is severely confused, agitated, rigid, or dangerously hot
Has chest pain or a very fast or irregular heartbeat
May have taken the medicine intentionally to cause self-harm
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
Contact a poison center immediately for any suspected overdose, even if there are no symptoms.
In the United States, call Poison Control at 1-800-222-1222 or use its online tool.
New breathing trouble, fainting, seizures, marked confusion, or worsening symptoms are not routine follow-up concerns; they need urgent assessment.
3
Does any of this apply?
Book an appointment
Seek routine follow-up after the immediate event for ongoing dizziness, concentration problems, mood changes, medication questions, or repeated dextromethorphan use.
And for anyone, someone who:
is having side effects from a medicine, or is struggling to take it as prescribed
The article also says
If possible, keep the package nearby.
Be ready to provide the product name, active ingredients, strength, estimated amount, time taken, age, and current symptoms.
Do not delay the call while trying to collect every detail.
Every sign above is quoted from the sofidex article on Dextromethorphan overdose. If you are not sure, err upward — it is always reasonable to be checked.