Zsa Zsa Gabor was not released from hospital on Saturday as expected, her publicist has said.
Doctors have decided to keep the 93-year-old actress at the Ronald Reagan UCLA Medical Center, three weeks after she was admitted.
She was taken to hospital in July after falling out of bed and breaking several bones.
Her publicist John Blanchette said she went into shock on Saturday and that she had a bad reaction to morphine.
Gabor is partially paralysed and uses a wheelchair following a car accident in 2002. She also suffered a stroke five years ago.
Gabor starred in films such as Moulin Rouge, Lili and Touch of Evil.