Meagan Toothman is on life support. Her family said they've decided to "allow her to be at peace."
They say an organ donation surgery is planned for later Monday.
Toothman was a head cheerleading coach at a Cincinnati High School. She was among those injured when a powerful gust of wind toppled the stage onto fans while waiting for the country band Sugarland to perform on Aug. 13.
Three fans and a security guard died at the scene, while a fourth fan and a stagehand later died of their injuries. Toothman will be the seventh fatality in the accident. Some four dozen people were hurt, many seriously.
The Associated Press contributed to this report.