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 now if someone may have taken an overdose and has slow or abnormal breathing, cannot be woken, has collapsed, is having a seizure, or has blue or grey lips or skin.
Give naloxone if it is available.
Follow the emergency dispatcher’s instructions for rescue breathing or CPR.
Contact a poison centre or emergency service immediately after any suspected excess dose, even if there are no symptoms.
Keep the medicine container or a photograph of its label available.
Do not delay the call while trying to count missing tablets.
And for anyone, someone who:
After discharge, seek urgent medical advice for worsening vomiting, right-sided upper abdominal pain, yellow skin or eyes, dark urine, increasing sleepiness, confusion, or unusual bleeding.
Routine follow-up is appropriate when the person is stable and following the hospital’s discharge plan.
It is used to repeat blood tests, review medicines, and address pain, substance use, or mental health needs.
And for anyone, someone who:
The article also says
Place an unconscious but breathing person on their side if this can be done safely.
Stay with them.
Do not give food or drink, put them in a bath or shower, or try to make them vomit.
Every sign above is quoted from the sofidex article on Hydrocodone and acetaminophen overdose. If you are not sure, err upward — it is always reasonable to be checked.