Mischa Barton was taken by police and hospitalized under California's involuntary psychiatric-hold law only hours before she was set to fly to New York for the premiere of her movie, "Homecoming."
The psychiatric-hold law allows authorities to hold a person for up to 72 hours if they present a danger to themselves or to others.
Barton, 23, looked bloated and disheveled at an appearance last week, which her reps blamed on the removal of a wisdom tooth.
The star was arrested for DUI and marijuana possession in LA after driving in two lanes during a break from the movie's location work in Pittsburgh last year. She later checked into rehab.
Barton's publicist told People, "Police were involved due to Ms. Barton's celebrity status to safely transfer her to medical treatment as per doctor's orders."
The rep said Barton was now "OK" and "resting."