The singer suffered a stroke at just 18, and requires constant checkups from doctors to monitor her condition.
Talking about the illness recently, Jessie explained: “I was in a girl band at the time and had, like, four jobs. I was really tired and my body shut down.
“It made me realise that no matter how much you take care of yourself – I don’t drink, smoke or do drugs – you can always have your life taken away.
“I thought I wasn’t able to perform again and that experience taught me that you can’t take anything for granted.”
But with Jessie's schedule increasingly getting full, and with The Voice UK live shows set to start in less than two weeks' time, friends fear Jessie is pushing herself too hard.
“Jessie has a history of medical issues and needs to be monitored," a supposed source told the Daily Star Sunday. “She works incredibly hard not only on The Voice but also promoting her album around the world.
“Add that to the gruelling touring, personal appearances and recording and it would be a lot for anyone to take.
“It’s not something Jessie really talks about but she still has health check-ups on her condition.”