With the iPhone 12, Apple introduced MagSafe as a way to charge the phone. It uses a set of magnets around a charging coil to connect the iPhone to the power adapter. MagSafe can also be used to attach accessories such as wallets or car mounts.
However, there’s long been an issue with magnets and medical devices that a person has implanted in their body. Heart Rhythm Journal recently posted the results of a study that showed that the iPhone 12’s MagSafe disrupted a patient’s implanted defibrillator.
Apple posted a support document noting that magnetic interference is possible with medical devices, and that users should consult with their doctor. Apple has updated that document with more specific advice:
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.
Before the update, the document merely stated that “although all iPhone 12 models contain more magnets than earlier iPhone models, no higher risk of magnetic interference with medical devices is to be expected than with earlier iPhone models.”
Apple does not publicly specify the strength of its MagSafe magnets. The Heart Rhythm Journal article does state that a magnetic field stronger than 10 Gauss can affect a medical device. The Heart Rhythm Journal’s study also states that, “prior smartphones without magnetic arrays” showed “minimal risk of electromagnetic interference.”
Obviously, if you have or are thinking of buying a MagSafe-equipped product and you have a medical device implant, never put it in a pocket that’s in close range of the medical device. It’s probably an even better idea to play it safe and not use a MagSafe device at all.