The FDA’s original position hinged on “inherent association”—that blood pressure measurement is “inherently associated with the diagnosis of hypo- and hypertension” regardless of disclaimers or intended use [3].

In my view, this legal theory was always a bit of a stretch. If any biometric that can be used for diagnosis automatically becomes a medical device, then the wellness device exemption Congress created in the 21st Century Cures Act [6,7]—that software intended for general wellness and not medical diagnosis or treatment is not considered a medical device—becomes meaningless. By this logic, bathroom scales would be medical devices because weight is “inherently associated” with obesity diagnosis, but you can walk into any store and buy a scale without FDA oversight.

In my original analysis, I argued that the real conversation shouldn’t be whether all blood pressure measurements are inherently diagnostic, but rather how the FDA’s wellness guidelines could and should be revised to allow biomarker collection while providing clear guidance on handling detected extremes.

The FDA found specific language from WHOOP that crossed into diagnostic territory, such as “higher blood pressure may be an indicator of poor sleep” and materials indicating that the feature was intended to identify “higher blood pressure” [3].

The distinction between “higher” and “high” blood pressure matters here. “Higher” describes a relative change from an individual’s baseline and should be acceptable for wellness devices. However, “high blood pressure” suggests comparison with clinical diagnostic thresholds. While WHOOP appears to have used “higher,” the FDA appeared to have interpreted this as “high blood pressure.”

The FDA objected to WHOOP’s user insights interface, claiming the color-coded (green/yellow/orange) readings imply medical interpretation, but most fitness wearables use similar color-coding schemes: for example, Garmin shows heart rate zones in green, yellow, and red, and Apple Watch displays activity rings with traffic-light logic.

If color-coding implies medical interpretation, are we going to start requiring submissions from manufacturers of street lights? This may be a tongue-in-cheek comparison, but the question remains: when does color-coding imply diagnostic categorization?

The FDA cited “evidence of individuals using BPI to monitor their hypertension” as a sign that WHOOP had overstepped the line. This original argument concerned me for two reasons.

First, using anecdotal misuse by some users to justify broad regulatory classification, especially when they provided no details about scale, frequency, or how this evidence was collected, would have set a concerning precedent. Second, people use fitness trackers for wellness purposes all the time, and those wellness issues often connect to more serious health conditions. Sleep quality can impact anxiety or cognitive health [8] and getting your 10,000 steps can help with overall cardiovascular wellness [9]. That shouldn’t make wellness device manufacturers liable for medical device indications.

While we want to be careful of products purposefully trying to skirt a medical device pathway, some off-label use is probably acceptable when it leads people to healthier lifestyles that could improve more serious conditions. And what’s the harm in someone with hypertension wanting to get an idea of their blood pressure, especially when the next step is probably to seek proper medical testing if they see warning signs?

Buried in the FDA warning is language that likely sealed WHOOP’s fate: their website originally described the blood pressure feature as delivering “medical-grade health & performance insights” [4,11].*

That single term was regulatory poison. In the FDA’s world, “medical-grade insights” implies clinical accuracy, validation standards, and regulatory approval, whether intended or not.

My original argument: you can have a wellness device that collects medical-grade data—in fact, this is preferred, because algorithms perform best when data are high-quality [12-14]. The problem was that WHOOP had originally used the term in reference to providing medical-grade insights, implying diagnostic-level blood pressure measurement.

If WHOOP had proposed changing this language in May, the situation may have been resolved sooner. However, the back-and-forth, while refusing adjustments, seemed to have gotten the FDA’s ire up. Additionally, with Aktiia and Apple subsequently receiving clearance for blood pressure and hypertension claims [15,16], it likely became harder for the FDA to give leniency.

Shortly after the FDA warning letter, WHOOP CEO Will Ahmed posted counterarguments on LinkedIn [17], making good points but ultimately overrelying on disclaimers to protect the company from oversight. In medtech, just telling consumers not to use a device a certain way often isn’t enough, especially if it contradicts other marketing claims.

There were also weaknesses in the arguments Ahmed made during his CNBC appearance at the end of August 2025 [18]:

Most damning to me when reviewing this debate is how WHOOP still structures subscription tiers, separating blood pressure insights from general “health monitoring” and bundling it specifically with FDA-cleared medical features in the highest tier [19]. They’re explicitly categorizing blood pressure insights alongside actual medical device features, telling consumers through product positioning that blood pressure monitoring belongs in the medical device category. It feels a bit like a magician’s misdirection—it implies medical device credibility to the consumer, while denying the need for medical device status to the FDA.