Some Apple Watch Series 12 and Ultra 4 owners report skin irritation under the sensor, MacRumors saysSome Apple Watch Series 12 and Ultra 4 owners report skin irritation under the sensor, MacRumors says

Some owners of the Apple Watch Series 12 and Apple Watch Ultra 4 say the new watches are irritating their skin, according to posts on the MacRumors forums and Reddit that MacRumors reported on 7 October.

The complaints describe a burning feeling and redness on the skin under the sensor on the back of the watch. Some owners say it settled down after a few days of wear, and some say cleaning the back of the watch and the band helped. Others have returned their watches. MacRumors is the only outlet to have reported the posts, and nobody has counted how many people are affected. Apple has not responded publicly.

What is different about the new sensor?

Several things, which is why owners are speculating. MacRumors lists them: both watches measure heart rate every five seconds, and they have a larger ECG electrode surface, photodiodes arranged in a ring, and larger green LEDs. Nobody has linked any of these to the irritation. MacRumors notes that wrist irritation has been a complaint since the original Apple Watch, so the reports alone do not show anything new.

What does Apple say causes Apple Watch skin irritation?

Apple's support article on wearing the watch, read on 8 October, says a small number of people react to materials, and gives allergies, environmental factors and long exposure to irritants such as soap or sweat as causes. A band that is too tight can irritate, and one that is too loose can rub. The article says the cases contain some nickel, below the European REACH limit, and that some cases and bands contain traces of acrylates and methacrylates from adhesives, though Apple says it keeps those parts away from the skin.

Apple's advice, from the same article:

• Wear the watch snug but comfortable, just above the wrist bone
• Loosen the band after a workout
• Keep the watch, band and skin clean and dry
• Clean the watch after sweat, soap, sunscreen or lotion
• With redness, swelling or itching, see a doctor before wearing it again

Our take

We cannot tell from forum posts whether this is a real fault or the usual complaints from a new watch. Forum threads attract the people with problems, launch weeks bring a lot of new owners, and some people react to any watch worn tight around the clock. The fact that some cases cleared up with cleaning and a looser fit fits that ordinary explanation.

Three things would change our view. A pattern tied to one model, case material or band. Apple updating its support article or issuing guidance specific to these watches. Or a watchOS update that changes how often the sensors run. That last one has happened before: watchOS 27.0.1 fixed the restarts after panic logs pointed to the Neural Engine, so these watches have already had one launch problem fixed in software.

The practical advice is plain. If your skin reacts, stop wearing the watch and follow Apple's steps above, and if it does not settle, see a doctor. Anyone still inside Apple's return period who has a reaction that does not clear should think about using it. APPDOOK will report if Apple or a medical source says more, since more frequent heart rate readings are among the headline changes in these watches.