Apple has released iOS 18.6.1, and it brings more than just routine fixes. The update restores the Blood Oxygen feature for Apple Watch Series 9, Series 10, and Ultra 2 in the United States, making it the most notable change in this release. Alongside this, the update also ensures smoother performance and stability across supported iPhones.
Anyone using an iPhone from 2018 or later can install iOS 18.6.1, which means models starting with the iPhone XS, XR, and newer all qualify. The update pairs with watchOS 11.6.1 to unlock the redesigned Blood Oxygen tool, which had been disabled in the U.S. due to legal issues. Now, Apple has introduced a new system that complies with regulations while keeping the feature available.
While the update may not change the experience for every iPhone owner, it matters for those who use Apple Watch health tracking. It also signals Apple’s focus on compliance without removing useful features. For most, the update is worth installing to stay current with security and system improvements.
What’s New in iOS 18.6.1
Apple released iOS 18.6.1 on August 14, 2025 as a minor update following iOS 18.6. While it doesn’t introduce flashy new features, it delivers important fixes and improvements that enhance stability and usability.
🔹 Key Changes in iOS 18.6.1
1. New Blood Oxygen Experience (U.S. Only)
- For Apple Watch Series 9, Series 10, and Apple Watch Ultra 2 users in the U.S.
- Blood oxygen measurements are now calculated on iPhone and displayed in the Health app, rather than directly on the watch.
- This change helps Apple navigate ongoing patent disputes while still offering the feature (source: MacRumors).
2. Targeted Bug Fixes
- iOS 18.6.1 primarily addresses a specific issue that arose in iOS 18.6.
- Reports suggest it fixes a syncing problem between iPhone and Apple Watch related to the new health features (source: Gadget Review).
- No major new features, but this patch ensures smoother performance.
3. Performance & Stability Improvements
- Minor under-the-hood optimizations for system stability.
- Some users report better battery life compared to iOS 18.6.
- General bug fixes to improve app responsiveness.
🔹 Should You Upgrade?
✅ Yes, upgrade if:
- You use an Apple Watch (especially Series 9/10 or Ultra 2).
- You experienced syncing or health tracking issues on iOS 18.6.
- You want the latest security and stability updates.
❌ You could wait if:
- You’re on iOS 18.6 and haven’t noticed any issues.
- You prefer to avoid frequent minor updates.
🔹 Looking Ahead
- Apple may release iOS 18.6.2 soon to address additional issues (rumored as of August 2025, source: Forbes).
- The next major update will be iOS 19, expected in September 2025 alongside the iPhone 17 lineup.
✅ Bottom Line
iOS 18.6.1 is a small but important update, mainly focused on:
- Adjusting how Blood Oxygen monitoring works with Apple Watch in the U.S.
- Fixing watch syncing issues.
- Improving stability and performance.
If you own a recent Apple Watch or want the smoothest experience, it’s worth updating.
Key Takeaways
- iOS 18.6.1 restores Blood Oxygen on Apple Watch in the U.S.
- The update works on iPhones from 2018 and newer.
- It improves stability and pairs with watchOS 11.6.1.
Key Changes in iOS 18.6.1
Apple’s latest iOS update focuses on restoring a key health feature that had been removed from recent Apple Watch models in the United States. It also introduces a new way of handling data by shifting some processing from the watch to the iPhone.
Restoration of Blood Oxygen Monitoring
The most important change in iOS 18.6.1 is the return of blood oxygen monitoring for U.S. users. Earlier this year, Apple disabled the feature on newer watches due to a legal dispute with Masimo, a medical technology company. This left owners of the latest models without access to a tool that had been standard on earlier devices.
With this update, Apple reintroduces the function but in a modified way. The blood oxygen feature now depends on the iPhone to calculate measurements instead of performing them directly on the watch. Users can once again view readings in the Health app, track trends over time, and use the data to monitor wellness.
This change makes the feature available again without violating the restrictions that forced Apple to disable it. While it may not work exactly as before, it restores a capability many users had relied on for daily health tracking.
Affected Apple Watch Models and Users
Not every device is impacted by this change. The restored function applies only to the Apple Watch Series 9, Apple Watch Series 10, and Apple Watch Ultra 2 in the United States. These models had their blood oxygen sensors disabled in watchOS earlier this year.
Older devices, such as the Apple Watch Ultra (first generation) or Series 8, were not affected and continue to work as before. Owners of the Series 9, Series 10, and Ultra 2 can now update both iOS and watchOS 11.6.1 to regain access.
This update matters most to users who purchased newer watches expecting full health tracking features. For them, iOS 18.6.1 restores functionality that had been missing since Apple complied with the court order linked to Masimo’s patent claims.
Technical Workaround and User Experience
Apple’s solution uses a workaround that shifts blood oxygen processing from the watch to the iPhone. Measurements are taken by the watch’s sensors but calculated and displayed through the phone. This ensures compliance with the legal ruling while still giving users access to their data.
The change means readings may take slightly longer to appear, since the watch must send data to the phone first. However, once processed, results show up in the Health app and can still be reviewed in charts and history logs.
From a user perspective, the experience remains familiar. The main difference is that the watch no longer handles the calculations independently. For most people, this adjustment will not affect daily use, but it highlights how Apple is balancing medical technology disputes with customer needs.
For more details on the update, see iOS 18.6.1 release coverage and Forbes’ breakdown of reactions.
Compatibility, Installation, and Related Updates
Apple’s iOS 18.6.1 update focuses on stability, security, and device compatibility. It works across a range of iPhone models, can be installed through built-in tools, and connects closely with the earlier iOS 18.6 release and its security patches.
Supported iPhone Models
iOS 18.6.1 supports the same devices as iOS 18. That includes newer phones like the iPhone 16 series and older models such as the iPhone XS, iPhone XR, and iPhone SE (2nd generation and later). Owners of these devices can install the update without issue.
Not every feature runs on every phone. For example, advanced tools like Apple Intelligence require newer hardware, while basic updates such as bug fixes and security patches apply to all supported devices.
A quick way to confirm support is to check Apple’s official compatibility list for iOS 18 devices. If a phone runs iOS 18, it can also run iOS 18.6.1.
How to Install iOS 18.6.1
The update installs through the Settings app. Users open Settings > General > Software Update, then choose Download and Install. A restart is required to complete the process.
For those who prefer automation, iPhones can apply updates overnight. This requires enabling Automatic Updates in the same menu. The device must be connected to Wi-Fi and charging for this to work.
Data and settings remain unchanged after the update. Still, many users back up their phones before installing any new version. Backups can be done through iCloud or a computer for extra safety.
Relationship with iOS 18.6 and Security Updates
iOS 18.6.1 builds directly on iOS 18.6, which introduced performance improvements, bug fixes, and changes to apps such as the Photos app where issues with sharing memory movies were corrected. Apple also released iPadOS 18.6, macOS Sequoia 15.6, and other updates at the same time to keep devices in sync.
Security is a major focus. According to Apple, iOS 18.6 included more than 20 security fixes for vulnerabilities. iOS 18.6.1 continues this effort with additional patches.
Keeping current ensures protection against known threats. Users who skip smaller point releases risk running outdated software with unpatched flaws. Installing iOS 18.6.1 provides the latest security defenses and stability improvements.
Frequently Asked Questions
iOS 18.6.1 focuses on security fixes, system stability, and small feature adjustments. It also restores certain Apple Watch functions, improves app reliability, and refines iPhone performance in daily use.
What are the latest security updates in iOS 18.6.1?
Apple included dozens of patches to close vulnerabilities in system frameworks and core apps. These updates strengthen device protection against potential exploits. More details on these fixes were noted in iOS 18.6 release coverage.
How has the battery performance been optimized in the latest iOS update?
The update improves background task handling and reduces power drain during standby. Some users report steadier battery life after updating, especially on older iPhone models.
What new features have been introduced in iOS 18.6.1 for enhanced user accessibility?
Accessibility improvements focus on smoother screen reader support and better text clarity. Apple also refined voice control performance to respond more accurately to commands.
Are there any improvements to Siri in the most recent iOS update?
Siri received minor tuning for faster response times. The assistant also shows improved accuracy when handling short, direct requests.
What changes have been made to the camera and photo functionality in iOS 18.6.1?
The update fixes a Photos app bug that prevented memory movies from sharing correctly, as noted in update notes for iOS 18.6. Camera stability also improved when switching between modes.
Has Apple introduced any new emojis or Animojis in this version of iOS?
iOS 18.6.1 does not add new emojis or Animojis. Apple focused this release on stability, security, and restoring features rather than expanding visual content.
