The U.S. Food and Drug Administration has deemed whole-body cryotherapy a shamand a risky one at that. In a new consumer update, the federal agency warns of the dangers of the "so-called 'treatment,'" offered at spas and wellness centers, that involves exposing one's legs, torso, and sometimes head to air chilled by liquid nitrogen to subzero temps (think -300 degrees). 

Proponents say that whole-body cryotherapy (WBC) not only supercharges metabolism, it's also an effective treatment for rheumatoid arthritis, asthma, depression, anxiety, migraines, fibromyalgiathe list goes on and on. The FDA’s response to those claims: Don't believe everything you read.

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“Based on purported health benefits seen in many promotions for cryotherapy spas, consumers may incorrectly believe that the FDA has cleared or approved WBC devices as safe and effective to treat medical conditions,” said Aron Yustein, MD, a medical officer in the agency's Center for Devices and Radiological Health. "That is not the case."

The trouble is, there's no good research on what exactly happens inside the body in extreme temperatures. "We simply don't know," FDA scientific reviewer Anna Ghambaryan, MD, PhD, said in the statement. The risks of WBC, however, are clear. Aside from the obvious hazards (like frostbite, burns, and eye injuries), asphyxiation can occur when nitrogen vapors reduce the amount of oxygen in an enclosed room.

The agency's warning may not come as a surprise if you read the news last October about a woman who died of asphyxia in a cryotherapy chamber in Nevada. Her death raised questions about the growing and largely unregulated trend.

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But the frigid cold isn't the only danger. The FDA noted that “patients who opt for WBC treatment—especially in place of treatment options with established safety and effectiveness—may experience a lack of improvement or a worsening of their medical conditions.” The agency urges anyone considering WBC to have a chat with their MD first.