The actress, who has had several problems in the past few months, is currently at the Malibu Promises clinic, where she will remain until her treatment has finished.
A source told the New York Post, "She is staying in Promises for longer than a month. We don’t know how much longer because of her work schedule, but she is taking rehab very seriously this time and not messing around."
Lohan was scheduled to leave the centre this weekend, after a month-long stay. This is the second time for the actress to be admitted into a clinic. She was arrested for driving while under the influence of alcohol last month.