Joe Perry collapsed on stage due to dehydration and exhaustion.
The 65-year-old guitarist was rushed to hospital after passing out at the Ford Amphitheater at Coney Island in Brooklyn on July 10 as he played with his band the Hollywood Vampires.
It had been speculated that Perry had experienced a cardiac arrest but now he has now revealed a combination of dehydration and exhaustion caused his collapse.
He was initially taken to Coney Island Hospital and then treated at Columbia Presbyterian in Manhattan before being discharged to return home to California where he is resting.
Perry has been touring the Hollywood Vampires - which also features Johnny Depp, Alice Cooper, Matt Sorum from Guns N' Roses and Robert DeLeo form Stone Temple Pilots - and his Aerosmith bandmate Steven Tyler has expressed concern the group has been over-booked, leading to the six string strummer's health issues.
Speaking to Pulse of Radio, the 68-year-old singer said: "I've had calls in for two days and I'm really concerned. I don't know what's going on with him and his management people. I just don't know and it's starting to scare me a little bit.
"I know they're putting out nothing but, 'He's recovering, he's really good, he fainted, exhaustion.' But I know my brother. And he's just about the only other guy that's just as passionate about his art as I am. He's always asking me to do three, four shows in a row. I know how to maintain my career, my health. I don't think he knows how to.
"I think he's out there and someone's over-booking him. Even though one could say the band booked themselves; well, that's righteous of 'em, but they're doing like eight or nine shows in a row - or five in a row. And I think they're all a little burnt. I think they need to look at that, Y'know, not young anymore, right?"
A statement released on behalf of the Hollywood Vampires has assured fans that Perry is "stable and resting".
A representative for the band told Rolling Stone: "Joe Perry is stable and resting. His brother Vampires and fans wish him a speedy recovery."