The 'At Last' singer's live-in doctor revealed recently that the legendary vocalist is "terminally ill".
The 73-year-old has now been admitted to a Southern California hospital and placed on a breathing machine, reports Reuters.
James's long-time manager Lupe De Leon said: "They took her to the hospital. She was having trouble breathing, so they intubated her. She is on a breathing machine and is resting."
De Leon admitted that the singer is "in pretty bad shape", adding: "It is really sad. She is like my sister."
James's family are at the hospital alongside her.
Etta, who suffers from dementia, was diagnosed with leukaemia last year.
In May, the Grammy winner and Rock and Roll Hall of Fame member developed a blood and urinary tract infection.
Watch Etta James perform 'Take It To The Limit' below: