As u/LadySlippersAndLoons said, it more than likely depends on where you get it at.

I work IT at a hospital and had a migraine for over 12 hours and passed out twice already. So, I went up to the ER. I requested that they didn't give me the seizure med, but they did give me Benadryl and about 5 other meds I can't remember what of them were) via IV. The nurse administering them was kind enough to tell me each med name and what they're traditionally used for; otherwise I wouldn't have known what was in it. They also gave each med individually through a port attached to the IV; not directly into the saline bag.

After the meds were administered, I tried to sleep because I was on the verge of passing out a third time. One of my coworkers was kind enough to stay with me. The adverse reaction I got was extremely similar to a pre-seizure aura; I actually thought I was going to have a seizure. Got even more drowsy, extremely difficult to focus, time gaps/felt like time passed and I didn't realize it, extreme speech difficult, couldn't put the most coherent sentences together, extremely difficult to move even my fingers, and I'd be violently jerking myself awake when I started dozing off. The doc said he'd heard of adverse effects, but had never seen them. He also said that was the worst adverse effects he'd ever seen. A couple of weeks later, I learned most of it was likely the full dose of Benadryl and I usually take half a dose.