Billie Joe Armstrong was a "functioning alcoholic" before he entered rehab.

The Green Day singer's drinking and reliance on prescription drugs had got out of hand before he was finally admitted to rehab last September and he admits to frequently being intoxicated on stage.

"I played onstage loaded a lot. I'd have anywhere from two to six beers and a couple of shots before I went onstage, then go and play the gig and drink for the rest of the evening on the bus. Fall asleep, wake up the next day, feel like s**t, do soundcheck. It was over and over again. In that way, I was a functioning alcoholic. I've been trying to get sober since 1997, right around Nimrod. But I didn't want to be in any programs. Sometimes, being a drunk, you think you can take on the whole world by yourself," he told Rolling Stone.

He also talked about how he used to carry so many prescription drugs his "backpack sounded like a giant baby rattle." He added, "I started combining them to a point where I didn't know what I was taking during the day and what I was taking at night. It was just this routine."

The band are now preparing to make their live comeback, which will take place this month.