iOS 18.6.1 Update Restores Apple Watch Blood Oxygen Feature via iPhone Processing

The long-awaited return of blood oxygen monitoring for U.S. Apple Watch users has arrived with the latest software update—iOS 18.6.1. Released alongside watchOS 11.6.1, this update brings back a key health feature that was previously disabled due to a high-profile patent dispute. Apple’s new approach ensures compliance with regulatory restrictions while restoring functionality in a smart, legally sound way.

In late 2023, Apple was forced to disable the blood oxygen sensor feature on newer Apple Watch models sold in the United States after the U.S. International Trade Commission (ITC) ruled that it infringed on medical patents owned by Masimo. As a result, Apple had to remove the capability from all Series 9, Series 10, and Ultra 2 models sold domestically. Watches sold internationally or prior to the import ban remained unaffected.

How does iOS 18.6.1 restore blood oxygen monitoring?

With iOS 18.6.1 and watchOS 11.6.1, Apple has reintroduced blood oxygen monitoring using a reengineered method. The hardware sensors on the Apple Watch still collect data, but instead of processing it on the watch itself, the measurements are now handled entirely by the paired iPhone.

This means that users can now view their blood oxygen levels in the Health app, specifically within the Respiratory section. While the data is no longer calculated directly on the watch, the end-user experience remains intuitive and useful for those who rely on blood oxygen insights for wellness or fitness tracking.

Importantly, this feature is only being activated on Apple Watch models sold in the U.S. after the ITC ruling went into effect—devices which were previously restricted from offering this feature. Watches sold before the ruling or outside the U.S. still retain the original on-device blood oxygen measurement functionality.

What else is included in iOS 18.6.1?

The update, released in mid-August 2025, appears to focus almost entirely on this health feature reactivation. Apple has not published any major security updates alongside iOS 18.6.1, and no Common Vulnerabilities and Exposures (CVEs) are associated with this version.

However, some users have reported minor issues following the update, including:

• Crashes in the Messages or Settings app

• Delays in syncing blood oxygen data between Apple Watch and iPhone

• Absence of blood oxygen stats directly on the Watch face

Despite these early reports, the broader consensus is that the update delivers significant functional value for health-conscious users. It underscores Apple’s ability to adapt its software quickly in response to legal challenges without compromising user experience.

Why this update matters for U.S. Apple Watch users

The return of blood oxygen monitoring in the U.S. is significant not just for health tracking, but also for Apple’s broader strategy of delivering premium wellness tools within its ecosystem. This update ensures that users of newer devices are not left behind, even amid ongoing legal battles.

By shifting processing duties to the iPhone, Apple successfully threads the needle between compliance and customer satisfaction. It’s a clever technical workaround that demonstrates both innovation and commitment to user health features.

Moreover, this software fix sets a precedent for how tech companies can navigate patent disputes without compromising their product offerings. For Apple Watch users, it means restored peace of mind and a renewed ability to monitor respiratory health in real-time.

Apple’s iOS 18.6.1 may seem like a minor update on the surface, but it marks a major win for user experience, compliance innovation, and health tech accessibility—all without needing to replace hardware.

For your information:

What is iOS 18.6.1 and why is it important?
iOS 18.6.1 is a minor but impactful Apple software update that restores the blood oxygen feature on Apple Watch models in the U.S. by moving data processing to the iPhone.

How do I enable blood oxygen monitoring on my Apple Watch after updating?
Once you install iOS 18.6.1 on your iPhone and watchOS 11.6.1 on your Apple Watch, the blood oxygen feature will activate automatically. View results in the Health app under “Respiratory.”

Which Apple Watch models are affected by this update?
The update applies to Series 9, Series 10, and Ultra 2 models sold in the U.S. that previously lacked blood oxygen capability due to the ITC ruling.

Will older or international Apple Watches be affected?
No. Apple Watches sold outside the U.S., or before the import restrictions were enforced, retain their original blood oxygen monitoring setup without change.

Can the feature work without an iPhone?
No. Under iOS 18.6.1, the Apple Watch sends raw sensor data to the iPhone, where it is processed and stored. An iPhone is required to view or analyze the data.

Are there known bugs in iOS 18.6.1?
Some users report syncing delays and app crashes, but no widespread bugs or vulnerabilities have been officially confirmed.