Yes, Lithium can cause nausea. :[

Awhile ago, they had put me on lithium, and it started to work out pretty good. Then, i was at my Lake House in NY at a diner for breakfast. I had to go outside before i ate, started vommiting very violently as my mom called it. I constantly vommited, had a headache, and i was def. surprised i didnt throw up any blood. heh. :/
Anyways, i had to get off of it ASAP-. I reccommend you telling your doctor as soon as possible, and lay off the coffee, etc..for a little bit, just so you can watch out for anything. But, dont take yourself off the medication, cold turkey!!!

Stay Well!!!!

deb*