Published on Aug 15, 2025 | By Aditya Kumar Singh | X | Linkedin
Last Updated | Aug 15 | 1:39 PM(IST)
Apple is officially bringing back the Blood Oxygen feature to select Apple Watch models in the United States through the latest iOS 18.6.1 and watchOS 11.6.1 updates. However, due to an ongoing patent dispute, the feature now works differently compared to before.
Background: Why the Blood Oxygen Feature Was Removed
In late 2023, Apple faced a US International Trade Commission (ITC) ruling following a patent dispute with Masimo, a California-based medical technology company known for its pulse oximeters. Masimo accused Apple of infringing on its pulse oximetry patents—the technology behind blood oxygen monitoring—and even alleged that Apple had poached employees to gain trade secrets.
The ITC ruled in Masimo’s favor, resulting in an import ban on certain Apple Watch models, including the Series 9 and Apple Watch Ultra 2, if they contained the disputed blood oxygen technology.
From January 17, 2024, Apple had to ship these watches in the US without the Blood Oxygen feature enabled, although units sold before that date—or purchased outside the US—retained the full functionality.
Apple’s Workaround: How the Feature Works Now
Apple’s latest updates to iOS 18.6.1 and watchOS 11.6.1 restore Blood Oxygen monitoring on affected watches, but with a key change to comply with the ruling.
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Original Method: Blood oxygen levels were calculated directly on the Apple Watch.
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New Method: The watch’s sensors now collect raw oxygen level data and send it to the paired iPhone, which processes the data and displays the results in the Health app’s Respiratory section.
This means that while you can still use your Apple Watch to measure blood oxygen, you’ll see the results on your iPhone instead of on your wrist.
Apple stated:
“Users with these models in the U.S. who currently do not have the Blood Oxygen feature will have access to the redesigned feature by updating their paired iPhone to iOS 18.6.1 and their Apple Watch to watchOS 11.6.1.”
Which Models Are Affected ?
The restored Blood Oxygen feature applies to:
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Apple Watch Series 9
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Apple Watch Series 10
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Apple Watch Ultra 2
Only units sold in the US after January 17, 2024—when the ITC ban took effect—are affected by this redesigned implementation. Watches sold earlier or outside the US still have the original on-device Blood Oxygen feature.
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US Customs Approval for the Redesigned Feature
Apple’s decision to reintroduce the feature comes after a recent US Customs ruling that allows the company to import watches with this redesigned technology.
By shifting the data processing from the watch to the iPhone, Apple has created a compliance-friendly workaround that satisfies regulatory requirements while still offering users access to oxygen monitoring.
Apple vs. Masimo: The Legal Battle Continues
The dispute with Masimo has been ongoing since 2021, when Masimo filed a complaint with the ITC. The company accused Apple of:
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Stealing pulse oximetry technology
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Poaching employees to gain medical tech expertise
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Using the technology without a license
Apple has denied these claims and countersued Masimo, accusing it of creating Apple Watch clones. The legal fight is still ongoing, with Apple appealing the ITC’s decision.
How to Get the Redesigned Blood Oxygen Feature
If you own an affected Apple Watch in the US, you’ll need to:
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Update your iPhone to iOS 18.6.1.
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Update your Apple Watch to watchOS 11.6.1.
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Use the Blood Oxygen app on your watch to initiate a reading—your results will appear in the Health app → Respiratory section on your iPhone.
Why This Matters for Apple Watch Users
Blood oxygen monitoring has been a key health feature since it was first introduced on the Apple Watch Series 6 in 2020. The removal of the feature earlier this year was a major setback for US buyers of the latest models.
Now, with this update, Apple is restoring the functionality without breaching patent restrictions, ensuring users can still monitor an important health metric—albeit in a slightly less convenient way.
This change comes just weeks before Apple’s upcoming iPhone launch event, where the company is expected to announce new Apple Watch models. The redesigned Blood Oxygen feature is likely to be a key selling point for Apple to reassure US customers that health tracking capabilities remain strong despite the legal dispute.
Whether the ongoing legal battle with Masimo will impact future Apple Watch innovations remains to be seen, but for now, Apple has found a creative way to bring back a popular health feature to its US customers.
Frequently Asked Questions
1. Which Apple Watch models and serial numbers are affected by the US ban and workaround ?
Affected models include the Apple Watch Series 9, Series 10, and Ultra 2 sold in the US after January 17, 2024, and bearing serial numbers ending with LW/A. These units had their Blood Oxygen feature disabled to comply with the ITC ruling—now restored via update.
2. How exactly does the new, redesigned Blood Oxygen feature work ?
Instead of calculating Blood Oxygen data on the watch, the Watch’s sensors now collect raw measurements and send them to the paired iPhone, which performs the calculations. The results are then accessible in the Health app’s Respiratory section.
3. What steps do users need to take to enable the feature ?
To restore Blood Oxygen monitoring, update your devices as follows:
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On your iPhone: Go to Settings → General → Software Update and install iOS 18.6.1.
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On your Apple Watch: Ensure it’s charged (≥ 50%) and open Settings → General → Software Update, then install watchOS 11.6.1.
4. Why might the Blood Oxygen app still show as unavailable even after updating ?
After installing the updates, your devices need to download an over-the-air asset that enables the redesigned feature. This may take up to 24 hours to complete. To expedite this, open the ECG app on your watch or open the Health app on your iPhone to trigger the asset download.
5. Is the new workflow permanent or will it revert once the legal issues are resolved ?
The current workaround—calculating Blood Oxygen on the iPhone—is a solution enabled by U.S. Customs to skirt the ITC-imposed ban while the legal dispute is ongoing. Apple has appealed the ITC ruling, and future changes may occur depending on the outcome. Masimo’s patents involved in the dispute are set to expire in 2028.
