FRIDAY, May 14, 2021 (HealthDay News) -- The U.S. Food and Drug Administration is warning that strong magnets in some cellphones and smartwatches can interfere with pacemakers and other implanted medical devices.

Studies have shown that these high-strength magnets may cause some implants to switch to "magnet mode," stopping normal functioning until the magnet is moved away from the device.

Many implants have a "magnet mode" so they can be safely operated during medical procedures, such as MRI scans. Doctors typically activate these features by placing a high-strength magnet near the implant. Removing the magnetic field restores normal operation of the medical device.

The FDA said patients with implanted medical devices should take these precautions:

• Keep cellphones and smartwatches six inches away from implanted medical devices, especially heart defibrillators. Do not carry these devices in a pocket over the medical implant.
• Check your device using a home monitoring system, if you have one. Talk to your doctor if you are having any symptoms or have questions about magnets in consumer electronics and implanted medical devices.
• When near high-strength magnets, devices with a magnetic safe mode could stop working or change how they work. For example, a heart defibrillator may not detect the rapid heart rate known as tachycardia. Or it may switch a pacemaker to asynchronous mode, blocking its sensing capabilities.

Implanted devices are designed to aid heart rhythm disorders, such as fast or slow heart rates. If the device stops working, a patient could get dizzy, lose consciousness or even die, the FDA warned in an agency news release.

The FDA conducted its own testing on some products that use the high field strength magnet feature and said that it considers the risk to patients low. The agency said it is not aware of any adverse events associated with this issue at this time.

More information

The U.S. Food and Drug Administration has more about the safety of implanted medical devices.

SOURCE: U.S. Food and Drug Administration, news release, May 13, 2021