The logo for the Food and Drug Administration is seen ahead of a news conference on removing synthetic dyes from America’s food supply, at the Health and Human Services Headquarters in Washington, DC on April 22, 2025.

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The U.S. Food and Drug Administration on Tuesday published a warning letter addressed to the wrist wearable company Whoop, alleging it is marketing a new blood pressure feature without proper approvals.

The letter centers around Whoop’s Blood Pressure Insights (BPI) feature, which the company introduced alongside its latest hardware launch in May.

Whoop said its BPI feature uses blood pressure information to offer performance and wellness insights that inform consumers and improve athletic performance.

But the FDA said Tuesday that Whoop’s BPI feature is intended to diagnose, cure, treat or prevent disease — a key distinction that would reclassify the wellness tracker as a “medical device” that has to undergo a rigorous testing and approval processes.

“Providing blood pressure estimation is not a low-risk function,” the FDA said in the letter. “An erroneously low or high blood pressure reading can have significant consequences for the user.”

A Whoop spokesperson said the company’s system offers only a single daily estimated range and midpoint, which distinguishes it from medical blood pressure devices used for diagnosis or management of high blood pressure.

Whoop users who purchase the $359 “Whoop Life” subscription tier can use the BPI feature to get daily insights about their blood pressure, including estimated systolic and diastolic ranges, according to the company.

Whoop also requires users to log three traditional cuff-readings to act as a baseline in order to unlock the BPI feature.

Additionally, the spokesperson said the BPI data is not unlike other wellness metrics that the company deals with. Just as heart rate variability and respiratory rate can have medical uses, the spokesperson said, they are permitted in a wellness context too.

“We believe the agency is overstepping its authority in this case by attempting to regulate a non-medical wellness feature as a medical device,” the Whoop spokesperson said.

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High blood pressure, also called hypertension, is the number one risk factor for heart attacks, strokes and other types of cardiovascular disease, according to Dr. Ian Kronish, an internist and co-director of Columbia University’s Hypertension Center.

Kronish told CNBC that wearables like Whoop are a big emerging topic of conversation among hypertension experts, in part because there’s “concern that these devices are not yet proven to be accurate.”

If patients don’t get accurate blood pressure readings, they can’t make informed decisions about the care they need.

At the same time, Kronish said wearables like Whoop present a “big opportunity” for patients to take more control over their health, and that many professionals are excited to work with these tools.

Understandably, it can be confusing for consumers to navigate. Kronish encouraged patients to talk with their doctor about how they should use wearables like Whoop.

“It’s really great to hear that the FDA is getting more involved around informing consumers,” Kronish said.

FILE PHOTO: The headquarters of the U.S. Food and Drug Administration (FDA) is seen in Silver Spring, Maryland November 4, 2009. 

Jason Reed | Reuters

Whoop is not the only wearable manufacturer that’s exploring blood pressure monitoring.

Omron and Garmin both offer medical blood pressure monitoring with on-demand readings that fall under FDA regulation. Samsung also offers blood-pressure-reading technology, but it is not available in the U.S. market.

Apple has also been teasing a blood pressure sensor for its watches, but has not been able to deliver. In 2024, the tech giant received FDA approval for its sleep apnea detection feature.

Whoop has previously received FDA clearance for its ECG feature, which is used to record and analyze a heart’s electrical activity to detect potential irregularities in rhythm. But when it comes to blood pressure, Whoop believes the FDA’s perspective is antiquated.

“We do not believe blood pressure should be considered any more or less sensitive than other physiological metrics like heart rate and respiratory rate,” a spokesperson said. “It appears that the FDA’s concerns may stem from outdated assumptions about blood pressure being strictly a clinical domain and inherently associated with a medical diagnosis.”

The FDA said Whoop could be subject to regulatory actions like seizure, injunction, and civil money penalties if it fails to address the violations that the agency identified in its letter.

Whoop has 15 business days to respond with steps the company has taken to address the violations, as well as how it will prevent similar issues from happening again.

“Even accounting for BPI’s disclaimers, they do not change this conclusion, because they are insufficient to outweigh the fact that the product is, by design, intended to provide a blood pressure estimation that is inherently associated with the diagnosis of a disease or condition,” the FDA said.

WATCH: Watch CNBC’s full interview with FDA commissioner Dr. Marty Makary