Apple on Thursday released iOS 18.6.1 for the iPhone and watchOS 11.6.1 for the Apple Watch Series 9, Apple Watch Series 10, and Apple Watch Ultra 2. The updates mark the return of blood oxygen monitoring to Apple Watches in the United States.
The iOS 18.6.1 update can be downloaded over-the-air on eligible iPhones, by going to “Settings” -> “General” -> “Software Update.”
The watchOS 11.6.1 update is available for newer Apple Watch models that have the blood oxygen monitoring feature disabled, and can be downloaded through the Apple Watch app on the iPhone.
Apple announced earlier today that the blood oxygen monitoring feature is making a return to U.S. Apple Watch models thanks to a “recent U.S. Customs ruling.”
Apple disabled the feature in 2024, when the United States International Trade Commission (ITC) found that Apple violated blood oxygen sensing patents owned by Masimo and implemented a trade ban. At that time, Apple stopped selling the Apple Watch Series 9 and Apple Watch Ultra 2, although sales resumed after Apple disabled the blood oxygen monitoring feature in Apple Watch devices sold in the U.S. Later models sold in the U.S. – including the Apple Watch Series 9, the Apple Watch Series 10, and the Apple Watch Ultra 2 – have also had the feature disabled. Today’s update restores the blood oxygen monitoring feature.
The iOS 18.6.1 and watchOS 11.6.1 updates include a workaround, where sensor data from the Blood Oxygen app on Apple Watch will be measured and calculated on the paired iPhone, with results being viewed in the Respiratory section of the Health app, instead of providing a readout on the Apple Watch itself.