Not just the visual but also the auditory and potentially the ulfactory.
The human body would react in the same way as it id had been poisoned (in fact alcohol is a poison..). When it's senses aren't reporting normally it purges the stomach as a reflex to prevent further/additional poisoning from whatever was consumed.
VR can trick the visual part of the brain into believing something that isn't backed up by the other senses. When this reaches whatever tolrance is in your brain you start to feel sick. Personally I find the effect creeps on incrementally with a feeling of bloat, followed by an elevated temperature/cold sweat across the face (usually face goes white about here) and then finally spinning ears/vertigo which can last minutes or hours... I'd expect the final symptom here to be vomiting. My wife is struck down with an almost instant bout of sickness from 10 seconds or less of VR, her brain just can't work it out but I can play most games for many hours except first person shooters which make me stage 1 or 2 within 30 minutes usually. I think gamers are quite tolerant to VR given the likely years that we've endured them.
It's millenia old genetic heritage we're at war with here. We must win.
