The 94-year-old was taken to UCLA Medical Centre on Saturday morning by her husband Frederic von Anhalt and was described as being in a 'very unstable' condition.
"She has a high fever and high blood pressure," Anhalt told Reuters, who confirmed that Gabor also had issues with her feeding tube.
Anhalt has since said that Gabor is responding well to antibiotics.
Gabor has suffered from several bouts of ill health in recent years, having been hospitalised in 2005 and again in 2007 after a stroke.
In July 2010, an accident forced to her to undergo a hip replacement, and earlier this year complications stemming from blood clots forced doctors to amputate her leg above the knee.
In May, Gabor spent just over a week in a coma in a coma after doctors discovered blood in her feeding tube.
> Zsa Zsa Gabor's husband Frederic Von Anhalt to run for mayor of Los Angeles