Yes, I also experience motion sickness if I do not do the following:
Options -> Video -> Display tab -> VSync = On
Options -> Video -> Quality tab -> Motion Blur = Off
Hit Apply after making each change.
To reduce eye strain (sometimes linked with motion sickness), I would suggest your friend take more frequent breaks (every 20-50 mins) and enable "Night light" mode (adds a sepia tone) if using Windows 10. Personally, I do not like to do the latter, as I prefer a more vivid color scheme (70 digital vibrance on Nvidia GPUs, or 140 saturation on ATI/AMD GPUs)