Fisher, 60, was rushed to UCLA Medical Center by Los Angeles Fire Department paramedics shortly after noon, after her 11-hour flight touched down at LAX.
Fisher, who rose to stardom as Princess Leia, recently published an autobiography titled the “Princess Diarist,” her eighth book.
She is the daughter of famous Hollywood couple Debbie Reynolds and Eddie Fisher.
Carrie Fisher, who has written and spoken openly about her struggles in Hollywood, is considered Hollywood royalty. She took on her prickly relationship with her mother in the book-to-movie "Postcards From the Edge.” She’s also been outspoken about her mental health issues and the solution she found — radical-sounding electroshock therapy.
News of Fisher’s condition sparked an outpouring of support and sympathy on social media.
Peter Mayhew, the actor who played Chewbaca, tweeted “thoughts and prayers for our friend and everyone's favorite princess right now.”
Actor Mark Hamill, who played Luke Skywalker, also took to Twitter: “as if 2016 couldn't get any worse... sending all our love to @carrieffisher”