Google received U.S. FDA clearance for Loss of Pulse Detection on Pixel Watch 3 on February 26, 2025. The opt-in feature looks for signs that the wearer may have lost a pulse; if the wearer does not respond to alerts, the watch attempts to contact emergency services and share location information. Clearance authorizes this specific feature in the United States—it does not mean every emergency will be detected or every call will connect.
What does Pixel Watch 3 Loss of Pulse Detection do?
Loss of Pulse Detection monitors for a potential absence of pulse while the watch is being worn. If it detects a possible loss and the wearer does not respond to a series of alerts, the paired phone or an LTE-connected watch attempts to call emergency services and provide location information.
Google announced the U.S. FDA clearance on February 26, 2025. The feature was first available with Pixel Watch 3 in European markets, then rolled out in the United States at the end of March 2025. Google Product Manager Edward Shi described it as having received “U.S. FDA clearance”; that is more precise than saying the watch or all of its health features are FDA-approved.
How does the watch detect a possible loss of pulse?
The feature combines readings from the watch’s optical heart-rate sensor with movement information. Google says the system uses AI and signal-processing algorithms to assess those signals before escalating to an alert.
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- The optical heart-rate sensor checks for a pulse signal while the watch is worn.
- If that signal disappears, the watch uses infrared and red lights for additional optical checks while its motion sensor looks for movement.
- Passive checks—including confirming that the watch is being worn and assessing movement—can take up to 20 seconds, according to Google’s Instructions for Use. They are intended to reduce false alerts.
- If the system continues to identify a possible loss of pulse, it starts the wearer alert sequence.
Google’s engineering account says development involved cardiologist input, clinical-setting data and hundreds of thousands of hours of real-life user data from a diverse group of people. Google also reports using stunt actors wearing tourniquets to simulate pulselessness and falls when validating emergency scenarios. These are descriptions of Google’s development work, not independent confirmation of performance.
What happens when the watch raises an alert?
- The watch vibrates and displays a check-in asking the wearer to respond. Google Help says this prompt remains for about 15 seconds.
- If there is no response, the watch sounds an alarm and starts an approximately 20-second countdown. The wearer can respond during the alert sequence to stop escalation.
- If the countdown expires without a response, the connected phone or LTE watch attempts to call emergency services and provide location information.
The staged alerts give a wearer a chance to cancel a false alarm. A poor pulse reading can trigger a check-in during normal activity; motion artifacts, ambient light, pressure on the skin, sensor-read quality and individual differences can affect readings.
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What performance figures has Google published?
Google/Fitbit’s Instructions for Use Rev C reports 69.3% sensitivity across 135 users. In the same document, specificity was analyzed using 131 evaluable participants and yielded one false-positive call over 7.75 user-years.
Those figures belong to the study and denominators described in the Instructions for Use; they are not a promise of detection for an individual wearer or a rate that can be assumed for every population or emergency. Google warns that the feature may not detect every event.
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Where is Loss of Pulse Detection available?
Google’s Pixel Watch Help page lists availability in Austria, Belgium, Canada, Denmark, France, Germany, Ireland, Italy, the Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, the United Kingdom and the United States. The feature’s availability depends on location; travelling into a region where it is unsupported temporarily suspends detection and calling.
Google’s U.S. clearance announcement does not establish regulatory status in every other country. Availability in a listed country should not be read as evidence of an identical regulatory authorization everywhere.
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What does the feature require to call for help?
- The watch must be charged and worn. Detection monitors only while the watch is being worn.
- A Wi-Fi model needs a phone connected to the watch over Bluetooth for the emergency-call attempt.
- An LTE model needs an active LTE connection. Some regions also require an active carrier plan or Safety Signal.
- Battery, radio, phone, LTE and network conditions can prevent a call from connecting. Emergency calling is an attempt, not a guarantee.
Who should not rely on it as a medical safeguard?
Google says Loss of Pulse Detection is not intended for people under 22, people identified by a clinician as being at high risk for sudden cardiac death, or people prescribed continuous cardiac or pulse monitoring. It does not diagnose, treat or determine the cause of a loss of pulse, and it does not replace medical monitoring or emergency care.
It is also distinct from features designed to assess heart rhythms such as possible atrial fibrillation: this feature is focused on a potential loss of pulse and the subsequent emergency-call workflow. It should not be treated as a general-purpose heart monitor.
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How do you turn on Loss of Pulse Detection?
- On the paired phone, open the Google Pixel Watch app.
- Tap Safety & emergency, then choose Loss of Pulse Detection.
- Complete the onboarding steps. You must be signed in to Personal Safety with a Google Account.
If the option is missing in a supported region, Google advises updating the Personal Safety app on the watch and the Pixel Watch app on the phone. The feature monitors only while the watch is worn.
What happens to the data?
Google says feature data, including heart-rate and movement data when a loss is detected, is stored on Google servers and is not sold or used for advertising.
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