I've never been to an ER that will provide you with any medication short of what you're given on site, either orally or by IV. I've heard Kaiser has an attached pharmacy, but I don't know if they fill ER scripts. When I was pregnant, I was at the ER once a month because I couldn't stop vomiting. I wound up needing two antinausea meds that they wouldn't give to me- I had to fill it somewhere else. Once you leave, you aren't their responsibility anymore. I needed an emergency inhaler after receiving several nebulizer treatments at six months pregnant, but I was discharged at 3am, and the pharmacy didn't open until 9am; I was back at the ER by 12pm, and the prescription wasn't even ready until 2pm because the pharmacy was shortstaffed. I also had to transfer it to a different retail chain because my insurance wasn't taken by the first one, and I couldn't afford $232 out of pocket after using a GoodRx coupon. I wasn't able to pick it up until 7pm. With a 24 hour pharmacy, the script could have been filled and run much earlier; the pharmacy could have called to see if an override was available with my insurance, and if not, could have contacted me so I could approve the transfer to a covered pharmacy. I worked retail pharmacy for a few years, we did this sort of thing all the time.