I'm worried about this too. I have IBS so my stomach already pretty much hates everything that goes into it. I don't imagine salty ass, literal dead sea water will be real pleasant for my already cursed GI tract.
From the other accounts I've read, it seems like the majority of people vomit even if they take an antienemic or other dopamine blockers. I do wonder if some of these cases are caused by failure to take Propranolol, which would potentiate the SN and lead to a shorter period of consciousness.
I am still scared, because I absolutely loathe vomiting and it brings back many terrible memories. However, I am going to take as much as I can of the supplementary medications when my time comes, so hopefully my French exit will be as peaceful as possible and I will not vomit while conscious.