According to preliminary findings of the investigation, a Paris gym employee died and a client was hospitalized in serious condition after a nitrogen leak during a cryotherapy session on April 14, 2025. What does this practice involve? Is it known to be dangerous?
This method, called " cold therapy", consists of placing a person for 2 to 3 minutes in rooms or cabins whose temperature can drop below -110°C. The person is immersed in bathtubs of iced water or nitrogen chambers. There are thus so-called "whole body" cryotherapy techniques, which also include the head (cryotherapy in a chamber) and "partial body" cryotherapy (cryotherapy in a cabin).
Cryotherapy: what are the benefits?
According to proponents of these therapies, in addition to calming pain, the cold forces the body to react by vasoconstricting (tightening the blood vessels). This limits their permeability and therefore the inflammatory response, which requires immune cells to leave the bloodstream to reach the tissues.
While the devices used were initially intended for high-level athletes, particularly to treat muscle pain after exercise, their use is now offered to people suffering from cancer, inflammatory diseases (ankylosing spondylitis), neurological diseases (multiple sclerosis) or even anxiety and depressive disorders, psoriasis, neurodermatitis and asthmatic disorders.
“ On the other hand, whole body cryotherapy is also used outside of any pathological context, to feel good, or even for aesthetic considerations.", worried the National Institute of Health and Medical Research (Inserm) in a report published in 2019.
Overall, even though cold has been known to have analgesic effects for thousands of years, the benefits of a cryotherapy session are extremely low. According to Inserm, studies investigating the beneficial effects of cold have shown disappointing results. On the one hand, when they support a positive effect of cryotherapy, these results are modest and measured only in the very short term. On the other hand, the methodological quality of the studies leaves much to be desired, which should lead to putting the reported positive effects into perspective even more.", the report stressed.
Read alsoCryotherapy: “Disappointing” effectiveness and significant side effects
Cryotherapy: a practice that is not without risk
Inserm also highlighted the risks associated with this practice. Whole body cryotherapy also poses genuine safety concerns.", the institute noted. It notably reports local first and second degree burns, headaches, chronic urticaria or even an increase in existing pain.
According to the first known information regarding the events of April 14, a nitrogen leak from the cryotherapy cabin is believed to have caused the poisoning. Nitrogen is an odorless gas that reduces oxygen in the air and can lead to such poisoning. A gym employee, born in 1996, died. Another person, a client of the establishment, born in 1991, was hospitalized and is in critical condition.
“ An investigation into the causes of death has been opened and entrusted to the police station in the 11th arrondissement of Paris, in joint consultation with the labor inspectorate.", said the Paris prosecutor's office, contacted by AFP. An autopsy and toxicological analyses have been ordered to determine the precise cause of death, which is believed to have occurred during a cryotherapy session." he said.
The cryotherapy cabin was reportedly repaired on April 14. The gym, which housed 150 people, was evacuated shortly after the incident, according to a police source.
AST with AFP
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