Actress Mischa Barton seems to have put her recent troubles behind her as she smiles with her trusty guitar on her way to catch a flight at Los Angeles International airport, July 28, 2009. [CFP]

Mischa Barton is on "the verge of another breakdown".

Concerned friends of the troubled actress, who was placed under involuntary psychiatric hold at Los Angeles' Cedars-Sinai Medical Center last month, fear she has returned to work on new TV series 'The Beautiful Life' too early.

Another friend revealed to the Chicago Sun-Times newspaper: "She is on the verge of another breakdown - one I think could be even more serious than the last one. She cries for no reason."

Mischa was hospitalised for 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 worried she was suicidal.

The 23-year-old actress arrived on the set of 'The Beautiful Life' just two days after being released from hospital.

It has been alleged the actress had been using drugs and alcohol to cope with her money problems and faltering love life.

In April 2008, Mischa pleaded no contest to drink driving and later checked into rehab to prove she "was sober".