Billy Bob Thornton has come clean about his past issues with substance abuse.

On the latest episode of the After Dinner Thinks with Ann Wilson podcast, the actor opened up about the period when he was doing psychedelics in his early 20s.

"I was a drug addict. I did everything," Thornton said. "I even was on morphine for a while, 'cause I had a nurse friend."

The actor added that he "did a lot of psychedelics" during that period.

"And what was funny about acid was, I didn't like it. I didn't have good trips. And I kept doing it because everybody else was doing it."

But the Landman star said he believes his experiences with psychedelics did have some benefits.

"I do believe it did unlock my mind to be a better artist," he said. "I honestly believe that psychedelics helped me as a writer and as an artist in general."

He continued, "It's so funny to think about those days, because it almost seems like another person to me. But I think it still resonates, and the residue of it is still around."

Thornton, who was married to actor Angelina Jolie from 2000 to 2003, quit drugs when he was 24.

"I'm glad I quit when I did," he said. "Because I was this skinny little long-haired hippie, working as a roadie, and I looked in the mirror on a trailer one day and said, 'You're gonna die. You have to stop.'

"Back then they didn't have programmes and support groups and things like that," he added. "I quit on my own."