I went to a hospital that was large enough to be the primary hospital for a county, and it had a rather large emergency room. I was not admitted. They increased my medication. I had family that could keep an eye on me, and they didn't think the environment in their impatient area would be a good place for me at that time. I was given information for outpatient treatment. I definitely second the suggestion to call ahead.
While you are waiting in the ER, they will need to check to see if you are under the influence and take away anything that could be used to harm yourself. A nurse and a security guard were present while they took my belongings. It is easier if you don't have any money on you when you go back, because they have to count it and recount it while they take inventory of your stuff. They won't want any of your belongings to be stolen. I was allowed to keep my underwear on, but I did have to remove my bra and lift my breasts. The security guard was a man, but stayed on the other side of the curtain while I undressed. The chairs were removed from the room. They took both a blood and urine sample.
I was not allowed to have anyone with me for at least the first hour of my wait, but they eventually let one person back to see me (with my permission) once it was clear that I was going to have a longer than average wait. I was monitored by the security guard the entire time. My room was in a secluded part of the ER, so I had privacy and couldn't see what was going on with other patients. Eventually, someone came to do an assessment, which was very thorough.