What’s New and Why It Matters
Introduction: A Feature That Came Back From the Dead
When Apple introduced the Blood Oxygen app on the Apple Watch Series 6 back in 2020, it was more than just another metric in the growing list of health features. It symbolized Apple’s ambition to transform its smartwatch from a fitness tracker into a serious health companion. For millions of users, it became part of their daily routine—checking oxygen saturation before workouts, monitoring levels at high altitudes, or simply gaining peace of mind during the COVID-19 pandemic when oxygen levels became a global concern.
Then, almost overnight in early 2024, the feature disappeared for new buyers in the United States. A patent dispute forced Apple to remove SpO2 functionality from newly sold Apple Watch Series 9 and Ultra 2 models, creating one of the most controversial product downgrades in Apple’s recent history.
Now, with the release of iOS 18.6.1 and watchOS 11.6.1, Apple has restored the feature, finally allowing users to once again measure blood oxygen with their wrist. The return of SpO2 is not just a technical update—it’s a story about innovation, regulation, health, and Apple’s determination to maintain its role as a leader in wearable health tech.
This article dives deep into the feature’s journey: why it disappeared, how it came back, what it means for users, and why it’s a much bigger deal than it may seem.
The Rise of Blood Oxygen Tracking
Blood oxygen monitoring, known medically as pulse oximetry, is not new. Hospitals have used fingertip pulse oximeters for decades to measure how well oxygen is distributed in the blood. These small clip-like devices became widely recognized during the pandemic when people bought them for at-home health monitoring.
Apple’s innovation was to miniaturize this into a wearable. With the Apple Watch Series 6, infrared and red LED sensors were integrated into the back crystal, bouncing light off blood vessels in the wrist. Using algorithms, the watch could estimate SpO2 levels—the percentage of oxygenated hemoglobin in the blood.
For the average user, it wasn’t meant to replace medical-grade devices but rather to provide general wellness insights:
Spotting patterns in oxygen levels during sleep.
Noticing drops during intense exercise.
Offering altitude adjustments for climbers and hikers.
Giving reassurance during illness or recovery.
The feature quickly became one of the flagship selling points of Apple’s health-focused strategy. By 2022, surveys showed that SpO2 tracking was among the most-used Apple Watch health tools, alongside heart rate and ECG.
The Legal Challenge: Masimo vs. Apple
The sudden removal of the feature wasn’t due to a technical flaw, but a legal battle.
Masimo, a medical technology company specializing in pulse oximetry, accused Apple of infringing on its patents related to blood oxygen sensors. In late 2023, the U.S. International Trade Commission (ITC) ruled in favor of Masimo, leading to a temporary import ban on certain Apple Watch models.
To keep selling the Apple Watch in the U.S., Apple made a tough call:
For existing users, the feature remained.
For new buyers of the Apple Watch Series 9 and Ultra 2, the Blood Oxygen app was disabled in software, even though the hardware sensors were physically present.
This unusual move created confusion and frustration. Apple Stores had to explain why the same watch might or might not have the feature depending on when it was purchased. Consumers felt shortchanged, and some even imported watches from outside the U.S. to regain access.
The situation turned into a rare instance where Apple was forced to remove, rather than add, functionality to one of its flagship products—a blow to its reputation as the gold standard of seamless upgrades.
The Turning Point: iOS 18.6.1 and watchOS 11.6.1
Fast-forward to August 2025. After months of negotiations, appeals, and behind-the-scenes adjustments, Apple quietly announced in the release notes of iOS 18.6.1 and watchOS 11.6.1 that the Blood Oxygen app is back.
What’s important about this update:
Restored for All Users: Owners of Apple Watch Series 9 and Ultra 2 in the U.S. can now re-enable the feature.
No Hardware Change Needed: Since the sensors were always there, it was simply a matter of reactivating software access.
Future-Proofing: The fix ensures that upcoming Apple Watches will launch with SpO2 monitoring active again, avoiding buyer confusion.
In typical Apple fashion, there was no dramatic press conference or flashy campaign. The company let the update speak for itself. But for Apple Watch users, this was huge news.
How Blood Oxygen Monitoring Works on Apple Watch
From a technical standpoint, the Apple Watch uses a combination of:
Red and infrared LEDs: Shining light into blood vessels in the wrist.
Photodiodes: Measuring how much light is absorbed.
Algorithms: Estimating SpO2 percentage based on how oxygenated hemoglobin absorbs light differently from deoxygenated hemoglobin.
Users can:
Take spot measurements using the Blood Oxygen app.
Allow the watch to perform background readings during sleep or inactivity.
View trends in the Health app on iPhone.
Apple emphasizes that the feature is for wellness, not medical diagnosis. However, many users have reported catching early signs of conditions—like sleep apnea or respiratory issues—because their watch showed abnormal oxygen drops.
Why It Matters: Health and Beyond
The return of SpO2 monitoring isn’t just about Apple winning a legal battle—it’s about the value of health data in everyday life.
1. Peace of Mind During Illness
During the pandemic, many people relied on blood oxygen monitoring to check for “silent hypoxia”—dangerously low oxygen levels without obvious symptoms. For families, the watch became a tool for reassurance.
2. Sleep and Fitness Tracking
SpO2 readings are integrated into sleep tracking, showing oxygen dips that may suggest snoring, altitude changes, or sleep apnea. Athletes also use it to optimize recovery.
3. Chronic Condition Monitoring
People with asthma, COPD, or other respiratory conditions often track oxygen saturation to manage their health better. While not FDA-approved as a medical device, the watch provides useful context for conversations with doctors.
4. The Bigger Ecosystem
Apple’s vision is a health-first ecosystem: pairing SpO2 with heart rate, ECG, temperature, and future sensors (like glucose monitoring) to give users a comprehensive health dashboard.
The Competition: Apple vs. The Rest
While Apple was caught in legal disputes, rivals like Samsung, Garmin, and Fitbit continued to advertise SpO2 tracking without restriction. Some reviewers even warned that Apple risked falling behind in the health wearables race.
Now that the feature is restored, Apple regains its edge. Its integration with iOS HealthKit and seamless ecosystem makes it more powerful than standalone metrics from competitors.
What Users Are Saying
On forums and social media, the reaction has been overwhelmingly positive:
“Finally! My Series 9 feels complete again.”
“I held off buying the Ultra 2 because of the missing SpO2. Now I can go ahead.”
“Crazy that it was ever disabled, but glad Apple fought to bring it back.”
For many, the update validated their loyalty to Apple, showing that the company was willing to fight for user experience.
Future Outlook: What’s Next for Apple Watch Health
The SpO2 saga highlights two key lessons for Apple’s future in health tech:
Innovation Meets Regulation
As Apple moves into deeper health territory—like blood glucose monitoring, blood pressure, or non-invasive medical scans—it will face regulatory and legal roadblocks. The SpO2 case was just a preview.
Health as a Selling Point
Apple knows that health features are now its biggest differentiator. Phones may plateau in innovation, but the Apple Watch can keep gaining relevance by monitoring more vital signs.
Conclusion: More Than Just a Comeback
The return of blood oxygen monitoring on Apple Watch is more than a toggle switch being flipped back on. It’s a statement about Apple’s resilience, priorities, and vision for health technology.
For users, it means peace of mind, better sleep insights, and a more complete wellness toolkit. For Apple, it marks a victory in the balancing act between innovation and regulation.
And for the industry, it signals that wearables are no longer just gadgets—they are becoming essential health companions.
In the end, Apple didn’t just bring back a feature. It brought back trust in its promise: that the Apple Watch isn’t just about time, notifications, or workouts—it’s about your health, your future, and the idea that technology can, quite literally, help you breathe easier.
