Tallulah Willis, the youngest daughter of Demi Moore and Bruce Willis, has allegedly entered rehab.

The 20-year-old fashion blogger was reportedly admitted at The Meadows treatment center in Wickenburg, Arizona in late July to seek help for her alcohol and cocaine issues.

"Tallulah was pretty much given an ultimatum," an insider told People.

"Her parents were about to take away everything from her," the source added.

On 24 July, Tallulah posted a cryptic messagee on her Twitter account.

Another source close to Tallulah told the publication that she was "adversely affected" by her parents' divorce in 2000.

Meanwhile, her former high school classmate revealed that Moore's hospitalisation and subsequent rehab stint in 2012 also took a toll on her.

"When Demi was hospitalised, Tallulah didn't show up to school for days because she was too embarrassed," the classmate said. "She was very open about Demi's issues and would sort of imply, 'Of course I have issues too, look at my mom.'"

Moore and Willis have visited Tallulah at the treatment center, but the Striptease star is more soft towards her daughter's condition.

"If Bruce suspected that Tallulah had any kind of substance abuse problem, he would have demanded for her to get help," a source close to Moore said. "Demi's take is that Tallulah is still very young and trying to find herself."