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 your local emergency number or poison control centre for immediate instructions.
In the United States, Poison Control can be reached at 1-800-222-1222 .
Call emergency services now if the person:
If they are not breathing normally, start cardiopulmonary resuscitation if you know how and follow the emergency call handler's instructions.
Keep medicine containers or packaging for emergency staff.
Routine follow-up is appropriate after emergency care for a medication review, ongoing sleepiness, concerns about dependence, or support following an intentional overdose.
And for anyone, someone who:
Treat a suspected oxazepam overdose as urgent, even if the person is awake or currently appears well.
New breathing problems, worsening drowsiness, repeated vomiting, or increasing confusion need urgent reassessment rather than a routine appointment.
And for anyone, someone who:
The article also says
If the person is unconscious but breathing, place them on their side if you can do so safely.
Do not make the person vomit.
Do not give food, drink, coffee, or a cold shower to try to wake them.
Every sign above is quoted from the sofidex article on Oxazepam overdose. If you are not sure, err upward — it is always reasonable to be checked.