By Breaking Celebrity News Staff

Heather Locklear was 'out of control' on alcohol and drugs when her sister Colleen called 911 for help, a source has told Entertainment Tonight.

The troubled actress, who has a history of drug and alcohol problems, was rushed to a suburban Los Angeles hospital after her worried sister rang for help.

As Breaking Celebrity News exclusively reported, Heather had been taking Xanax and had been drinking heavily when Colleen intervened.

Less than 48 hours earlier, Heather was visibly intoxicated when she sat courtside at a Laker's game.

"Heather becomes a different person on drugs," the source told ET, adding that her on-again-off-again relationship with former fiancé Jack Wagner has been particularly tough for her to handle.  The fact that he's sober and she's not was the cause of their latest break-up.

Locklear's daughter Ava is now staying with her father, Heather's ex-husband Richie Sambora.