AceShowbiz - Lindsay Lohan is facing a 30-day jail sentence after failing her latest court-ordered drug test, according to U.S. reports. The "Mean Girls" star is trying to rebuild her reputation after serving time behind bars and in rehab following a probation violation issue earlier this year, stemming from her 2007 DUI arrest.

But the 24 year old, who was treated by addiction specialists for her prescription drug use, could find herself incarcerated once more after a drug test taken "in recent days" came back positive, reports People.com. Sources tell TMZ.com the drug in question was cocaine.

If the claims are true, she will face 30 days in jail. And a Lohan insider tells TMZ the news will hit the actress hard, "People with addiction problems don't get better magically, and she's really been making an effort to make herself better."

However, Lohan will have to wait to hear the final verdict - Sandi Gibbons, a spokeswoman for the Los Angeles District Attorney's office, which is handling her case, has yet to be "officially notified" of the test results.

Lohan is currently undergoing intense outpatient treatment following her release from rehab in August. As part of her punishment, the embattled star is subjected to random drug testing twice a week. The actress' representative had yet to respond to requests for a comment as WENN went to press.