The operating system brought a new look to the iPhone, but some users report that the swoopy animations and parallax effects are making them woozy, giving them headaches, nausea or even vertigo.
Doctors say that motion-sickness can be caused by the eye seeing movement when there isn't any, but it generally takes a few minutes of sustained motion for the sensation to kick in, according to ABC News.
Affected users can turn off some of the visual effects through a "reduce motion" option in the operating system's settings, but many 3-D effects stay on regardless.
Once users update their operating system, however, they're stuck with it. Apple does not allow users to downgrade once the new software has been released.