Frontman Billie Joe Armstrong of Green Day smashes his guitar during the 2012 iHeartRadio Music Festival in Las Vegas, where he had an onstage meltdown. (Christopher Polk/Getty)

Green Day frontman Billie Joe Armstrong has opened up about his alcohol and prescription-drug abuse in the wake of his onstage meltdown last year and subsequent stint in rehab.

Armstrong sought help for what he's said were longtime addictions after an onstage rant at a music festival in Las Vegas in September. He smashed his guitar and started screaming expletives after his band was told to wrap up.

According to Armstrong, he can't recollect much from that day or night. “I woke up. I asked [my wife] Adrienne, ‘How bad was it?’ She said, 'It's bad,'" he recalled in an interview published in the latest issue of Rolling Stone magazine.

Armstrong then spoke to his manager, who told him he would be going straight to rehab and cancelled the rest of the band's tour. Prior to the Las Vegas outburst, Armstrong had been briefly hospitalized in Italy with an undisclosed illness, but was able to later perform at the MTV Video Music Awards as well as at other gigs.

In the Rolling Stone article, released in the new issue on newsstands Friday, the 41-year-old singer reveals that he would often lose consciousness and could never predict where he was “going to end up at the end of the night.”

“I’d wake up in a strange house on a couch. I wouldn’t remember how. It was a complete blackout.”

Award-winning band to resume tour

The Grammy-winning band, which formed in the 1980s, has sold 65 million records worldwide. The trio's hit albums include Dookie, Insomniac and American Idiot, which spawned a popular Broadway musical of the same name.

The band is launching the postponed tour — in support their trio of recently released albums Uno, Dos and Tre — on March 28 in Chicago. The slate includes concerts in Toronto (April 11) and Quebec City (April 12). The tour moves to Europe in the spring and ends in Bilbao, Spain, on July 13.

In an online posting in January, Armstrong thanked his family, friends and fans:

“I wanted to thank you all for all the love and support you've showed for the past few months," he wrote.

"Believe me, it hasn't gone unnoticed and I'm eternally grateful to have such an amazing set of friends and family. I'm getting better every day. So now, without further ado, the show must go on.We can't wait to get on the road and live out loud! Our passion has only grown stronger."