Apple Watch uses an on-device algorithm to passively monitor optical heart sensor data over 30-day periods and alert users if it detects consistent signs of high blood pressure (hypertension). The feature launched with watchOS 26 in September 2025, received FDA clearance, and is available on Apple Watch Series 9 and later in more than 150 countries.

Hypertension notifications use data from the optical heart sensor (photoplethysmography) to analyze how a user's blood vessels respond to heartbeats — a pattern associated with arterial stiffness and elevated blood pressure. The algorithm runs passively in the background and evaluates data over rolling 30-day periods before alerting the user. The feature was developed using training data from over 100,000 participants and validated in a clinical study of more than 2,000 participants, as stated in Apple's Apple Watch Series 11 launch. Apple states the feature will not detect all instances of hypertension and is not intended to replace clinical diagnosis. It is intended for users 22 years or older who have not been previously diagnosed with hypertension and are not pregnant.