Some Apple Watch Series 12 and Ultra 4 owners have reported unexpected skin irritation, according to MacRumors forums and Reddit. Users describe a burning sensation and redness under the sensor area. The watches measure heart rate every five seconds, and design changes include a larger ECG electrode, ring-shaped photodiodes, and larger green LEDs. It is unclear if these cause irritation, but wrist issues date back to the original Apple Watch.
Apple states reactions may stem from a band being too tight or too loose, or from irritants like soap and sweat. Some models contain nickel below EU limits, and Apple says it is unlikely a problem. Trace amounts of acrylates and methacrylates from adhesives are present but kept away from skin, per Apple.
Apple recommends proper band fit and keeping the watch, bands, and skin clean and dry, especially after workouts or exposure to liquids. Some users report improvement after an adjustment period or cleaning; others have returned devices. Apple advises consulting a physician for persistent redness, swelling, or itchiness before wearing the watch again.
Source: MacRumors · Summarized by HeadlinesBriefing