Philadelphia Phillies star Bryce Harper is leaning on an alternative offseason recovery tool, EBOO — Extracorporeal Blood Oxygenation and Ozonation — a therapy that he said boosts circulation and reduces inflammation.
Harper posted an Instagram video earlier this month showing himself hooked up to tubes and a machine administering EBOO.
The procedure involves drawing blood, treating it with a laser and ozone, and then reentering it into the body. Proponents of the treatment, which Harper’s doctor, Josh Reed, gives, say that EBOO helps athletes with recovery and is regulated in some countries outside the U.S. However, the FDA told The Athletic that the agency “has not approved any medical devices for EBOO therapy,” and its regulations call ozone “a toxic gas with no known useful medical application.” Treatment in the U.S. is seen as an alternative and takes place in private clinics.
Reed said he works “with a ton of high-profile professional athletes.”
“You take blood out of one arm, it goes through a laser, then it gets ozonated, it gets filtered … and it goes into the other arm,” Reed said of the treatment, which lasts about an hour.
The goal of ozone therapy is to increase oxygen in the body. Proponents, including Reed, say it can help the immune system. In Harper’s Instagram post, he said the treatment kicked off “a great week of wellness.”
However, according to a 2022 Cleveland Clinic article, there have not been enough clinical trials to ensure the treatment’s safety and efficacy, compared with potential negative side effects. Safety concerns persist, including a case of neurological complications after intravenous ozone that was published in the “Archives of Academic Emergency Medicine” earlier this year. The study highlighted risks of air bubbles leading to a blocked vein or artery, and the dangers of inhaling ozone, which can damage the lungs.
When Harper’s video went viral, some fans on social media wondered if the treatment met MLB’s doping rules.
The procedure is not currently prohibited under the 2022-2026 collective bargaining agreement. The Phillies did not immediately respond to a request for comment.
Harper has also spoken about drinking raw milk, which is favored in some health circles. The FDA, however, cautions against it because it could carry Salmonella, E. coli and other harmful bacteria. The milk is also banned for sale in some states.
Harper, who turned 33 in October, posted an .844 OPS in 2025, his lowest mark since 2016. Still, it ranked 22nd among 145 qualified batters in the major leagues.
Harper hit 27 homers in 132 games this past season. He missed time with a nagging right wrist injury.