Mischa Barton's friends fear her partying could jeopardise her rehabilitation and health.
The former 'O.C.' actress - who was placed under involuntary psychiatric hold at Los Angeles' Cedars-Sinai Medical Center last month - has infuriated her close pals by partying at the All Points West music festival in New York just days after her release from hospital.
Family friend Eric Ziegenbein told Heat magazine: "It's scary to see her out right after she's received treatment. When I found out she'd been partying again, I was shocked. I thought she would chill out for a bit.
"The fact she was out right away proves she's not taking things seriously enough. It was like a big 'f**k you.' She's too proud and independent sometimes."
The 23-year-old starlet spent two weeks under a 5150 hold - which allows people to be forcibly held if they are deemed a danger to themselves or others, are gravely disabled or have a mental disorder - after friends became concerned she was suicidal.
It has been alleged the actress' drink and drug use was affecting her career and personal.
Another friend, Suzanne Coppin, is frustrated Mischa is not listening to the advice of loved ones and is trying to deal with her problems alone.
She explained: "She has a support group, but it's obvious she's ignoring them. I'm disappointed she's not taking advice and is still doing her own thing."
This is not the first time the actress' friends have voiced concerns about her wellbeing.
Earlier this month, they openly expressed their fears she had returned to work on her new TV series 'The Beautiful Life' too soon after leaving hospital.
One said: "There still are issues. Mischa's just not herself at all. I think she's gone back to work too soon."