Myself and two others experience mild nausea about 20 minutes after taking Diesel Fuel. Usually lasts about 30-45 minutes but sometimes can be prevented with food. It honestly feels like a massive drop in blood sugar cause. Kind of makes you want to lay down for a while.
And I'm referring to the current non-stimulant version. I'm thinking it's either the fo-ti or the gynostemma... or the combination of them. I've been able to reproduce the feeling in a homebrew of gynostemma and fo-ti.