Apple Watch owners have been left shocked after realising the expensive gadget can now predict illness before symptoms have even started.

The device which, can identify heart problems and falls in the elderly, can now predict illnesses before symptoms have even been spotted.

The new Vitals app, which is available with the latest operating system, WatchOS 11, is able to prevent common illnesses such as the flu and COVID.

It does this by analysing the heart rate, respiratory rate, wrist temperature, blood oxygen and sleep duration and Apple Watch owners have reported that the device can spookily pick up on little changes in their bodies.

Users took to social media platform Reddit to share their shock.

One user shared a screenshot of their Vital data in a thread titled “The Vitals app knew I was sick 3 days before I did.”

The data revealed that a key measurement was that their wrist temperature had been higher than normal for three days.

The app will notify a wearer when two or more of their vitals have changed, for example, their heart rate, breathing rate or wrist temperature.

An example of a notification a user might receive is: “During sleep, your respiratory rate and wrist temperature were higher than normal.”

The Reddit user received notifications on the first two days and then came down with the flu on the following day. Other social media users also shared their experiences with the app, mostly praising the software as “amazing” and “clever.”

Apple does not claim it can miraculously diagnose or treat medical conditions.

Instead, the company presents the app as a tool for users to gain a better understanding of their health.

Users can then opt to turn on notifications if their watch takes measurements outside of their normal range.

An Apple spokesperson said: “When two or more metrics are out of their typical range, users can receive a notification, along with a message detailing how the changes in these specific metrics may be linked to other aspects of their life, such as elevation changes, alcohol consumption, or even illness,

“Vitals uses an algorithm developed using real-world data from the Apple Heart and Movement Study, research that aims to advance the understanding of the links between heart health and physical activity.”