Lorazepam
"Ativan is the only drug that can stop my vomiting when I'm in the middle of a bad cycle (I have cyclical vomiting syndrome which is triggered by neurally mediated hypotension.) I've never had any nasty side effects. I just get pleasantly loopy and very sleepy which is usually a blessing after staying up all night. I don't have a prescription for it so I end up in the ER a few times a year which is when they give it to me. (By the time it's that bad, I need IV fluids anyway so...)"