Users of Apple's new iPhone operating system say the animations are leaving them feeling nauseous and with headaches.
The iOS 7 operating system uses animations when apps "zoom" in and out and "depth" effects.
"Apple's new operating system is making me nauseous and giving me a headache, just like when you try to read in the car," one user said.
Others complain of vertigo or seasickness-like symptoms.
iOS 7 comes pre-installed on new iPhone 5C and 5S models, and other models are available to upgrade. One of its main selling points was its simplified look.
Apple includes an option to reduce animations, but has not made an official statement on the issue.