Apple has released iOS 18.6.1 for iPhone, alongside watchOS 11.6.1 for Apple Watch. The update introduces a redesigned Blood Oxygen feature for Apple Watch Series 9, Apple Watch Series 10, and Apple Watch Ultra 2 units sold in the United States, addressing the restrictions caused by the ongoing patent dispute with medical technology company Masimo.
The dispute had previously forced Apple to disable the Blood Oxygen app on affected Apple Watch models in the U.S. to comply with an International Trade Commission ruling. With iOS 18.6.1 and watchOS 11.6.1, Apple has restored the capability using a new method that avoids infringing the contested technology while still delivering oxygen saturation data to users.
Apple’s release notes summarize the update:
This update provides a new Blood Oxygen experience for users in the United States with Apple Watch Series 9 and Series 10, and Apple Watch Ultra 2. Measurements are calculated on iPhone and viewed in the Health app.
Instead of showing results directly on the Apple Watch, the measurement process now involves the watch collecting raw sensor data and sending it to the paired iPhone for analysis. The iPhone processes the information and displays the results in the Health app, under the Respiratory section. This change allows Apple to reintroduce the feature while remaining within legal boundaries.
The redesigned implementation does not affect Apple Watch models sold outside the U.S., nor does it change how the feature works on older devices that were never impacted by the ban. For users in affected regions, the update restores a core health tracking capability that many rely on for monitoring wellness and fitness.
Along with the Blood Oxygen redesign, iOS 18.6.1 likely includes the usual bug fixes and security improvements, though Apple has not detailed all the changes. As with all point updates, it is recommended for all compatible iPhone models to ensure devices stay protected against potential vulnerabilities.
The update can be installed by going to Settings > General > Software Update on the iPhone. For the Blood Oxygen feature to work again on Apple Watch, users must also update to watchOS 11.6.1 through the Watch app. Both updates are required for the redesigned system to function properly.
The reintroduction of Blood Oxygen monitoring demonstrates Apple’s ability to adapt its technology to overcome legal challenges without removing important health features permanently. For users in the U.S. who have been without this function for months, iOS 18.6.1 is a welcome restoration that makes their Apple Watch feel complete again.
