A TikTok trend appears to be bringing cold water immersion back into the public discourse, with some claiming that “cold plunges” are a good way to fight inflammation and boost the immune system.

Also known as cold water therapy, cold plunges typically involve rapidly submerging oneself in water colder than 60 degrees Fahrenheit.

“Traditionally, cold therapy has been performed by athletes in an effort to enhance post-workout recovery,” said Dr. Craig Van Dien, a rehabilitation specialist at Hackensack Meridian Health’s JFK Johnson Rehabilitation Institute, Forbes reported. “There has been growing interest amongst the general population, possibly as a consequence of the purported health benefits and wellness trends.”

While some medical professionals disagree on the veracity of such health benefits, there is much agreement on the risks. Plunging into cold water can ramp up the production of the hormone norepinephrine, which can lead to significant increases in blood pressure and heart rate. The dynamic can prove dangerous for those suffering from obesity, one of the most widespread preventable diseases in the United States.

Dr. Kristi Colbenson, a Mayo Clinic sports medicine and emergency physician, advises that obese people should probably avoid experimenting with cold plunges, especially without a doctor’s input, reported NBC 5.

Van Dien agrees:

“Understanding your medical comorbidities and what risk they pose is extremely important before cold plunging. At a minimum, individuals with known cardiac or pulmonary disease should steer clear of cold water immersion, given the immense burden placed on these body systems.”

Some medical professionals still doubt whether substantial benefits can be gained from the practice at all. Dr. Tracy Zaslow, a sports medicine physician at Cedars-Sinai Kerlan-Jobe Institute, suggested there is insufficient data to support the current hype.

“There have been a couple of studies showing that there may be some decreased soreness after people were immersed in cold water for about 10 minutes versus those who did not do any cold therapy,” Zaslow said, according to the Cedars-Sinai Blog. “When you’re in cold water, your blood vessels constrict so there’s less blood flow to the area, then there’s less swelling and inflammation leading to less pain.”

She also pushed back against the idea that cold plunges improve mental health.

“The study that showed it might be helpful for mental health looked at people who took a course in swimming in cold seawater,” Zaslow claimed. “But exercise can improve your mood and wellbeing. To me, it’s a soft case that it was the cold water providing the aid.”