Promethazine
"I have been taking Promethazine 25mg tablets as needed for nausea for about 5 years. 1 pill would completely take away my nausea, even if I had the flu. However, the first time taking 1 pill knocked me out. You can build up a tolerance fairly quickly if you take them daily. I also have taken 1 to 2 pills to sleep through the night if im off work the next day because they make me groggy for a few hours the next morning. They don't make me feel "out of it" like Xanax and I have never developed any type of addiction to them either."