# Apple Watch Series 12 and Ultra 4 owners report burning, redness under the sensor

Source: https://idevice.com/apple-watch-series-12-and-ultra-4-owners-report-burning-redness-under-the-sensor
Published: 2026-10-07

> Some Series 12 and Ultra 4 owners report burning and redness under the sensor, and nobody has confirmed a cause. Apple advises a clean, well-fitted band and a physician visit if irritation appears.

Some [Apple Watch Series 12](https://idevice.com/smart-watches/apple-watch/roadmap) and Ultra 4 owners are reporting a burning sensation and redness on the skin under the sensor, according to posts on the MacRumors forums and Reddit.

Series 12 and Ultra 4 read heart rate every five seconds. Both watches also carry a larger ECG electrode, photodiodes in a ring-shaped arrangement, and bigger green LEDs. Affected owners say the burning and redness sit under the sensor area. Some of them have wondered whether the more frequent readings are the cause. Nobody, including Apple, has confirmed it.

Apple's standard guidance on wrist irritation points to bands worn too tight or too loose, and to soap and sweat trapped against the skin. Some Apple Watch models contain nickel, but Apple says the amount is low and a reaction is unlikely. The case and certain bands carry trace amounts of acrylates and methacrylates from adhesives, which Apple says it designs to keep away from skin.

Apple's advice is to keep the watch, the band and the wrist clean and dry. Cleaning may be needed after workouts or exposure to liquids like sweat, soap, sunscreen and lotion. Anyone with redness, swelling, itchiness or other irritation should consult a physician before wearing the watch again.

Wrist irritation isn't new to the Apple Watch. The complaint dates back to the original model, and it is unknown if any of the new design changes is a problem. Some owners say the problem cleared up after an adjustment period, and cleaning the back of the watch and the band has helped in some cases. Others have returned their watches.