Have a pacemaker? Keep your cell phone at least 6 inches away

Magnets used in portable devices including cellphones and smart watches may impair pacemakers and affect other implanted devices, the Food and Drug Administration warned Thursday. 

The FDA advises keeping cellphones and smart watches at least 6 inches away from pacemakers, defibrillators and other potentially life-saving mechanisms to avoid potential interaction. 

The magnets can inadvertently cause the medical devices to enter "magnet mode," causing them to stop functioning, according to the agency. The devices are supposed to go into magnet mode during medical procedures such as an MRI scan, but can lead to adverse consequences in other scenarios.  

Interactions between the magnets and medical devices are rare, according to the FDA. Still, the agency warns consumers with implants not to carry their portable devices in nearby pockets.

"When near high-strength magnets, devices with a magnetic safe mode could stop working or change how the device works. For example, a cardiac defibrillator may be unable to detect tachycardia events," the FDA said in a statement. 

The agency noted that the risk to patients is low and that it is unaware of any adverse incidents linked to the potential effect of gadgets on medical devices.

Apple's warning

Apple in March warned consumers that iPhone magnets might interfere with medical devices.

"Medical devices such as implanted pacemakers and defibrillators might contain sensors that respond to magnets and radios when in close contact," the company said on its website. "To avoid any potential interactions with these devices, keep your iPhone and MagSafe accessories a safe distance away from your device (more than 6 inches / 15 cm apart or more than 12 inches / 30 cm apart if wirelessly charging). But consult with your physician and your device manufacturer for specific guidelines."