There have been numerous reports recently of iOS 7 causing motion sickness with some users. This seems to be a result of many of the motion effects built into the new OS. For instance, the swift zooming in and out of apps when launching or exiting them, and the subtle but perhaps off-putting 3D parallax effect that separates the app icons from the background when tilting your phone.
Unfortunately, you can’t turn off the zooming motion when you launch an app, but there is a setting to turn off the parallax effect that we’ve previously covered here. Hopefully you’re not susceptible to motion sickness, but if you are, at least turning off parallax motion may help.