IN a stunning development, CHER and her transgender son CHAZ have been rocked to the core over a heroin drug nightmare!

The showbiz icon’s troubled son Elijah Blue Allman is boozing again after years of sobriety, and Cher, 66, is wracked by fears that the former junkie will go back on heroin. So she shipped him off to rehab, The ENQUIRER has learned.

Cher or­ganized an intervention when she learned her 36-year-old wild child had relapsed, sources say, and Chaz, 43, played a major role.

“Cher was blown away when she found out Elijah was drinking again,” a family source told The ENQUIRER. “But she shifted into protective moth­er mode and took charge of getting him off booze and any drugs he may be doing for good. The first thing Cher did was to get Chaz on board. Chaz has always tried to watch out for his little brother, so his involvement was key.”

THE OSCAR-WINNING ACTRESS HAD organized a similar intervention in 2003 for Elijah, whose father is rock legend Gregg Allman.

“Cher thought he’d gotten clean then, and this time she got right in Elijah’s face and read him the riot act,” said the source. “She threatened to cut him off financially if he didn’t get help, and Chaz was right at her side. They double-teamed Elijah, and he had no choice but to give in.”

The “Believe” singer also recruited her pal Mel Gibson to help, according to the source.

“Mel is close with a guy who runs an exclusive treatment center in Malibu, and the next thing you know, Elijah was admit­ted,” said the source. “Fortunately, he offered no resistance.”

Cher opened up about Elijah in a 2010 interview, saying that he was “doing really well. He’s a good artist, a painter.”

Elijah, who’s also an aspiring musi­cian, has been living with his fiancée, Marieangela “Angie” King, at his mother’s Malibu mansion. They met in Cologne, Germany, where Angie, 25, was play­ing in a band with her four siblings.

As The ENQUIRER has reported, Cher was shaken when she learned that Elijah was engaged to Angie, who was raised in the contro­versial sex cult Children of God. But she’d come to accept her, said the source.

“Cher was hoping Elijah would marry Angie and settle down,” added the source. “Now she’s just praying he can kick his booze habit and stay far away from heroin.”