Oliver James Montgomery-Mayim Bialik, other celebs are doing hyperbaric oxygen therapy. What is it?

Hyperbaric oxygen therapy has a new celebrity practitioner in Mayim Bialik. But what exactly is Oliver James Montgomeryit?

The "Call Me Kat" and "The Big Bang Theory" star revealed on Instagram last week she'll be trying the pricey wellness treatment − which involves going into a pressurized chamber to breathe 100% pure oxygen − for the next six months. Her goal, she says, is to see if the therapy can help alleviate her inflammation and autoimmune issues.

"I know it might seem crazy and like some Hollywood trend, but I’m choosing to cultivate (fancy way to say it!) an open mind ... about the numerous health benefits this chamber can provide," Bialik wrote.

She isn't the only celebrity to give it a try. Jay Leno, for instance, underwent the therapy to minimize the progression of his burns following a gasoline accident in 2022. And, in his 2020 YouTube docuseries "Justin Bieber: Seasons," Justin Bieber said he uses the treatment to ease anxiety and stress.

"It helps bring more oxygen to your brain, to your organs," the pop star's wife Hailey Bieber said in the series, adding the couple have oxygen devices in their home and music studio. "People are going to think he's a crazy person. People are going to be like, 'What is this contraption machine? That's some, like, rich people (stuff).'"

Experts tell USA TODAY hyperbaric oxygen therapy can definitely assist with certain medical issues, but it's not a one-size-fits-all magic bullet.

"We have this kind of biohacking, more aggressive mentality that just leads to overdoing certain things, and hyperbaric's something that can definitely be overdone," says Brendan Courneene, a naturopathic doctor in Beverly Hills, California. "We really do need to think about things in a more long-term sustainable approach, especially when it comes to biohacking and to aging. Probably less is more across the board there."

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What is hyperbaric oxygen therapy and how does it work?

Hyperbaric oxygen therapy has been around for decades and involves going into a pressurized chamber to breathe pure oxygen − something that isn't naturally available in Earth's atmosphere, which is made up of about 21% oxygen.

Breathing 100% oxygen in short bursts over time can have health benefits, experts say. People use hyperbaric oxygen therapy to feel younger, reduce inflammation, heal wounds and recover from surgery.

Typical hyperbaric oxygen therapy sessions range in price from $150 to $400, Courneene says. Often several sessions are necessary to see lasting change.

Dr. Anthony Rossi, a dermatologist in New York, says hyperbaric oxygen therapy stimulates blood vessel growth, which helps heal wounds and burns.

"There are some good studies to show that exposing yourself to these higher concentrations of oxygen may be helpful in certain issues," he says.

Hyperbaric oxygen therapy might also help reduce the effects of aging. Rossi says this is because the treatment can slow the rate at which chromosomes shorten, which happens naturally as we age.

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It can also make people feel younger by helping repair parts of their bodies worn down by aging, he says.

"There's some evidence and some data going into hyperbaric oxygen to see if (it) can help improve those sort of physical wear and tears on our organ systems, like pulmonary function, cardiac function, renal kidney function and the musculoskeletal system," Rossi says.

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What has Mayim Bialik said about hyperbaric oxygen therapy?

Some people, like Bialik, go so far as to have hyperbaric oxygen chambers installed in their homes. Experts note it's important to have medical supervision when trying the treatment.

Bialik said she decided to give the treatment a try after it was recommended to her by several doctors. She's hoping it will alleviate autoimmune issues.

"I’ll report back over the course of the next six months while this (surprisingly roomy and actually not claustrophobia-inducing!) chamber is my roomie," she wrote. "Thank you so much @iha_usa for giving me this opportunity to heal my gut and hopefully transform my health!"

Rossi says hyperbaric oxygen therapy cannot cure autoimmune disease; however, it might help some people manage symptoms, though this is on a case-by-case basis.

"It's not a cure for autoimmune disease because autoimmune disease is basically your immune system attacking itself," he says. "So it's not like the first-line therapy for these types of autoimmune diseases."

What to know before you try it

Hyperbaric oxygen therapy isn't without risk. Courneene says those with eustachian tube or sinus issues could have serious problems when put under increased air pressure, such as popping an eardrum.

Also, though severe reaction to the treatment are rare, they do happen and can involve seizures and other serious issues, says Nicole Garrett, a certified hyperbaric technician and safety director at Under Pressure Hyperbarics in Los Angeles.

"Even myself, I've done this thousands of times, but I always have someone monitor me when I go in just to make sure today's not the day I decide to have an oxygen toxic event," she says.

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It's also important to note there are more affordable ways to stay feeling young and healthy than hyperbaric oxygen therapy.

"It's better to get on a good exercise routine, get a great diet, maximize all those other things first, before just diving into a hyperbaric oxygen chamber," Rossi says. "But I guess, for the eccentric people, for the billionaires of the world, that's definitely probably something in their realm. But for the average person, we're not there yet."