5ht-3 antagonists.
Ondanserton, beta-pinene in lemon essential oil, and its also in ginger.
Works wonders for serotogenic nausea ime. And its not just mumbo jumbo, theres scientific evidence to back up the efficacy of 5ht-3 antagonists as remedy's for psychadelic induced nausea. But it can also affect the trip, since you are changing how your receptors are being hit by throwing an antagonist into the equation.
It works very well for harmalas&mescaline in my expirence though. That's a pretty nauseating combo, but much more bearable with a few drops of lemon essential oil.