In the U.S., Democratic presidential candidate Hillary Clinton’s health has become a heated topic in the media. Clinton left the 9-11 ceremony early feeling unwell.

Many, including her Republican rival Donald Trump and his supporters, question whether she is healthy enough for the White House.

On Sunday, U.S. Presidential candidate Clinton was about to enter a vehicle after a September 11th ceremony in New York City.She hesitated, then crumpled, then leaned on her aides, who help her into a van.

Clinton’s campaign told reporters she was “overheated,” only to later release a doctor’s note saying she had been diagnosed with pneumonia two days earlier. In a statement, Clinton’s doctor said: “She was put on antibiotics and advised to rest and modify her schedule.”

When Clinton had a coughing fit on the campaign trail just over a week ago, Trump questioned whether she was healthy enough to be president.

“I think it's an issue. In fact, this week, I took, this last week I took a physical and I’ll be releasing when the numbers come in. Hopefully they’re going to be good,” Trump said.

Many presidents have been less than candid about their health. Though voters knew that polio had paralyzed President Franklin Delano Roosevelt, many did not know he could not walk. The press did not take pictures of him in a wheelchair.

Americans also knew John F. Kennedy had back trouble, but he never disclosed he had Addison’s diseas, a disorder of the adrenal glands.

Now the Clinton campaign is promising to release more details about her health in the coming days.

“We’ve been in touch with her this morning and it is our intention in the next couple days we’ll release additional medical information about Hillary Clinton,” said Brian Fallon, Clinton spokesperson.

“I think, in retrospect, we could have handled it better, in terms of providing more information more quickly.”

Clinton is finally taking a break, canceling an appearance in California Monday. Clinton’s running mate, Tim Kaine, says Clinton’s energy “staggers” him.