Caleb Followill's drinking got so out of control he needed steroid injections for his voice.
The Kings Of Leon frontman hit the bottle hard while the band were touring, and by the summer of 2011 he needed jabs just to be able to sing and keep up the pace.
He told the new issue of Q magazine: ''When you're going as fast as we were going, or working as hard as we were, you get into a rhythm.
''Then it becomes a case of, well, if I'm gonna go out there and kick ass tonight then I need to grab a couple of drinks first.
''And I'm going to need a steroid shot just to sing. After a while, that gets on top of you.''
Caleb eventually had to deal with his self-destructive behaviour and decided to quit boozing for a year, and now only enjoys the occasional drinking session.
The 31-year-old rocker said: ''I gave up drinking for about a year. I needed a break ... I eased myself back in. I know when it's time to let my hair down now and when it's time not to.''
Kings of Leon have no plans to call time on the band despite Caleb's brother and bandmate Nathan Followill revealing the singer's heavy drinking caused tensions to run high.
Caleb said: ''I know people thought we were going to break up but I was never going to quit, put it that way. And how do you break up with your brothers, anyway?''
The raspy-voiced star needn't worry about slipping back into his old ways since his Victoria's Secret Angel wife, Lily Aldridge, and his 14-month-old daughter Dixie Pearl are accompanying the group on tour this summer to keep a watchful eye on him.
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The film is expected to continue without Mendes' involvement.