I use Zyrtec generic for antihistimine. It may be the only one I can use...my pcp looks up on the web to find which drugs are safe for my other illness, Porphyria. Zyrtec is not sedating. I take it at night, but I can be awake anyway, and never wake up drowsy from it. It is timed released. I take it for the violent itch associated with another ailment, Polycythemia Vera. I would hate to take an antihistimine which would make me groggy to the point where I was unsafe driving in the neighborhood, or unsafe on stairs.
I have never had nausea from an opiate like Demerol so I'm out of the picture there.