Magnets in cell phones and smart watches may affect implanted medical devices

May 14, 2021

Some consumer electronic devices, such as certain cell phones and smart watches, include high field strength magnets. Recent studies have shown that consumer electronic devices with high field strength magnets may cause certain implanted medical devices to switch to “magnet mode” and suspend normal operations until the magnet is moved away from the medical device, the U.S. Food and Drug Administration (FDA) warned.

“Many implanted medical devices are designed with a ‘magnet mode’ to allow for safe operation during certain medical procedures such as undergoing an MRI scan. These safety features are typically engaged by physicians with the use of a high field strength magnet that is placed near the implanted device placing it into a ‘magnet mode’ Removal of the magnetic field causes the device to return to normal operation," the FDA said.

That is why devices with a magnetic safe mode could stop working or change how they work when near consumer electronics with high field strength magnets. “For example, a cardiac defibrillator may be unable to detect tachycardia events. Or it may change the operational mode of the devices such as turning on asynchronous (i.e., two or more events not happening at the same time) mode in a pacemaker,” the FDA said.

The FDA recommends that people keep any consumer electronic devices that may create magnetic interference, including cell phones and smart watches, at least six inches away from implanted medical devices, such as cardiac defibrillators.

The FDA said published articles describe how sufficiently strong magnetic fields can turn on the magnetic safe mode when in close contact. The FDA said it also conducted its own testing on some products that use the high field strength magnet feature and has confirmed this phenomenon.

However, the FDA also said it believes the risk to patients is low, and said it is not aware of any adverse events associated with this issue.

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