Okay, so how about this hypothetical:The person next to you feels nauseous at the smell of alcohol because they're so hungover from the night before?
Does that elicit as much sympathy as if they were simply allergic to alcohol? Would it affect your course of action?
Offer a little hair of the dog. Cures hangovers every time.
***Just kidding. I know that sounds terrible. I wouldn't do that. But, in all seriousness, if they were nauseous from being *that* hung over, they are probably not in any condition to fly in the first place...but if they do so anyway, just about any foodstuff or activity (or motion from the airplane in the first place) is likely to make them sick. In such a case, I would probably ask the FA to re-seat one of us just to ensure that I am *far* away from any vomit.