In their announcement, his bandmates did not specify what kind of illness that eventually forced the band to cancel an Italian concert.
Green Day's frontman Billie Joe Armstrong has been released from the Italian hospital he was admitted to over the weekend. His illness remains undisclosed but published reports said he was suffering from "gastric problems".
The rock band, who are promoting their September 25 album "Uno!", were forced to cancel their Sunday, September 2 concert in Bologna, Italy when Armstrong was rushed to hospital on Saturday. Armstrong's bandmates, Tres Cool and Mike Dirnt posted a video message on YouTube, apologizing to the fans.
"We're beyond devastated," said Cool. "We're as sad as you guys are. Billie is extremely upset about it, and we'll see you very soon." Dirnt added that "doctors didn't think it's a good idea" for Armstrong to perform at the I-Festival on Sunday.
The bassist and the drummer continued, "We are beyond devastated and will make it up to you when we come back next summer." The band have mapped out a huge concert in U.K. next summer, taking the vast Emirates Stadium as venue.
Update: Armstrong was spotted back in Los Angeles on Monday, mouthing to reporters that he has lost his voice.