The latest iPhone 5S and 5C may be the top favorites of many techies, but  doctors are alerting  iPhone users to reconsider iOS 7 upgrades, following several complaints of digital animations and effects in the new iOS 7, which leads to motion sickness. 

Apple has set new sales records with the launch of its new iPhone 5S and 5C with more than 9 million units sold during the first weekend. The new Apple iPhones  debut the tech giant's updated mobile operating system, the iOS 7. The new OS was downloaded on more than 200 million devices as it came with a major overhaul compared to its previous version.

The iOS 7 come with numerous features, but the OS has a slight glitch in the transitional effects between the home screen and individual apps, which in turn have a major impact on users' physical health. Several Apple fans have been vociferous about  the iOS 7 screen effect, which apparently gives rise to nuasea. The excitement of getting a new phone often comes in the way of finding any errors, hence several users overlooked this problem. But once some people reported the matter, users bombarded Twitter and Apple forums.

Several users who experienced the iOS 7 screen effects said that it resulted in nausea, headaches, dizziness and motion sickness. Dr. George Kikano, division chief of family medicine at UH Case Medical Center in Ohio, told FoxNews.com that people's claims are true. But he said it was not the zoom animations but the  new "parallax" function that was making people feel dizzy.

"The inner ear is responsible for balance, the eyes for vision," Kikano, who had firsthand experience with his new iPhone5S, said in a statement. "When things are out of sync you feel dizzy, nauseous. Some people get it, some people don't, and some people get used to it."

The parallax function causes the background to move back and forth resulting in a sick feeling.

Kikano also suggested that Apple allows users to reduce motion by turning down the parallax effect on icons and alerts. This option can be found under Settings --> General --> Accessibility --> Reduce Motion. Despite changing the settings some users still reported motion sickness while using the device.

Listed below are a few comments by very aggravated users, who vented out their frustration on the social media and Apple forums.

"I thought I was going crazy today after I updated my phone and I noticed I was feeling queasy every time I used it. Now I see I am not alone! I just used my phone for about 20 minutes and now I feel like I'm going to vomit. There has to be a way to turn this off!" user knphoto10 wrote on Apple forum.

"Im having the same issues with dizziness from the animations. I reverted back to iOS 6.1.4 on my iPhone5. I love the new iOS7 design but the side effects of feeling sick made it a deal breaker," wrote another user.

If iOS7 is really making people feel motion sick, and Apple didn't know, it shows a lack of testing with real people https://t.co/nvIgJdUBTH

- Steve Evans (@steve_e) September 28, 2013

I find iOS7's animations in and out of apps completely nauseating. I need to make it stop! It is making me motion sick. Ugh. - Rebecca Mushtare (@cyberthread) September 21, 2013

iOS7 > Settings > General > Accessibility > Reduce Motion . Still feeling sick

- Chris (@chrisada) September 19, 2013.