Virtual reality games are here, but before you rush out to buy the gear, you’ll want to heed the warnings. Children under 13 are not advised to play, and if they do, parents should limit the playing time.

“These devices are designed mostly for adult use,” Vancouver optometrist Dr. Justin Asgarpour said.

Little research has been done about the long-term effects of VR on children, but manufacturers have not designed the VR headsets for young eyes.

VR headset manufacturer Oculus Rift states that improper sizing can lead to discomfort or health effects, and younger children are in a critical period of visual development.

“What a study has suggested is that a VR device can actually trigger what we call amblyopia, a potential lazy eye, in these children with pre-existing visual conditions,” Dr. Asgarpour told CTV News.

Even children without underlying eye conditions could experience problems, like temporary double vision.

Adults should beware too, according to the doctor, who says prolonged exposure to the virtual reality experience can lead to disorientation and balance issues. You should be aware of your surroundings and be cautious not to trip over wires. Pregnant women are advised not to play as well as those with heart conditions.

But there are some positive health applications with virtual reality. VR has been used to treat phobias like fear of heights, and it’s also being used to help treat addictions.

“What we’re trying to do is take people into a virtual crack related neighborhood or crack related setting and let them experience craving,” Dr. Zach Rosenthal with Duke University told ABC News.

He and his team take addicts inside a virtual crack house and use a series of tones to condition them to reduce their cravings. Those tones can later be accessed on their mobile phones when they are experiencing cravings.

A lot more research needs to be done about the long term health effects of VR, but in the meantime you are advised to limit your exposure and monitor and limit the time that your children play.