"Rarely, on more than one occasion, over the last many, many years, the same sort of thing's happened to her when she got severely dehydrated, and she's worked like a demon, as you know, as secretary of state, as a senator, and in the years since," Bill Clinton told Charlie Rose, in a clip of an interview aired on CBS Monday evening.
Hillary Clinton told CNN's Anderson Cooper Monday such episodes have happened "really only twice that I can recall."
"You know, it is something that has occurred a few times over the course of my life, and I'm aware of it, and usually can avoid it," she said. "What happened yesterday was that I just was incredibly committed to being at the memorial -- as a senator on 9/11, this is incredibly personal to me."
Bill Clinton said Hillary Clinton is "doing fine" now as she recuperates from pneumonia at home in New York.
"She was even better last night before she went to sleep. She had a good night's sleep. She just got dehydrated yesterday," the former president told Rose of Hillary Clinton's early departure from a commemorative ceremony at Ground Zero in Manhattan -- and her stumble at her campaign van.
Clinton's campaign revealed hours later Sunday that she'd been diagnosed Friday with pneumonia, and said she'd become overheated that morning. Bill Clinton said nothing more serious is happening.
"Well, if it is (more serious) then it's a mystery to me and all of her doctors," Bill Clinton said.
When Rose noted Clinton's age -- at 68, she'd be among the oldest first-term presidents -- and her grueling campaign schedule, Bill Clinton pointed to his wife's more recent campaign events.
"She had two-and-a-half hard days before the day when she got dizzy," he said. "Today she made a decision, which I think was correct, to cancel her campaign day to take one more day to rest."
Asked if the former secretary of state could miss weeks on the campaign trail, Bill Clinton said: "No, not a shot. I'll be lucky to hold her back another day."
Clinton canceled a planned trip Monday to California. Her campaign has said it will release more details about her medical history later this week in an effort to demonstrate she isn't suffering greater health problems.
Bill Clinton's comments came as he defended the Clinton Foundation's work
, arguing that accusations of conflicts of interest are baseless and come from politically motivated Republicans.
"There's never been a foundation to disclose as much as I have," he said. "Then why don't people feel trust? Because of the way the disclosed information is selectively used."