Update

Appendix Surgery for Lindsay Lohan

UPDATED 01/05/2007 at 07:40 AM EST • Originally published 01/04/2007 at 03:25 PM EST

Lindsay Lohan had surgery to remove her appendix on Thursday.

"She does have appendicitis, and she is getting her appendix removed," her rep, Leslie Sloane, told PEOPLE Thursday afternoon. "She will be going in shortly."

The 20-year-old actress was reportedly diagnosed after feeling ill on Wednesday.

"I'm shocked," a friend of the actress tells PEOPLE. "I talked to her last night and she told me she was not feeling well but she thought it was a 24-hour-flu."

This is not the first health scare for Lohan. She fractured her wrist in September after a fall at a party in New York City, and was hospitalized in July after becoming "overheated and dehydrated," Sloane said at the time.