Biles doesn't want to say what happened to her, but on Instagram she describes it as "one of, if not the scariest experiences of my life."
The 29-year-old's photos include images from the hospital showing her wearing a hospital bracelet and a screenshot of a heart rate monitor.
"I'm not one to normally share things like this because I value privacy. But being close to death wasn't on my bingo card earlier this week."
Simone Biles writes that she is now resting and says she will tell more later about what happened.
The American gymnastics star, who has seven Olympic gold medals, three of which came from Paris 2024, has not decided whether she will compete in Los Angeles 2028.
