Democratic presidential nominee Hillary Clinton has been diagnosed with pneumonia, her doctor said Sunday, after the former secretary of state made an early exit from an event commemorating the September 11, 2001, terror attacks in New York.
A video shared widely on social media appeared to show Clinton stumbling and requiring assistance as she entered a van.
An initial statement from spokesman Nick Merrill said that Clinton had "felt overheated" after spending 90 minutes at the 9/11 ceremony.
Clinton's doctor, Lisa Bardack, later issued a statement saying the former first lady had become overheated and was suffering from dehydration after having been diagnosed with pneumonia on Friday.
"Secretary Clinton has been experiencing a cough related to allergies. On Friday, during follow up evaluation of her prolonged cough, she was diagnosed with pneumonia. She was put on antibiotics, and advised to rest and modify her schedule," Bardack said.
After the incident Clinton was taken to her daughter Chelsea's residence, from which she later emerged and said: "I'm feeling great, it's a beautiful day in New York," according to the Washington Post.
The episode comes amid recent speculation about the state of Clinton's health by supporters of Republican candidate Donald Trump, which Clinton's camp has dismissed as conspiracy mongering.
Neither 68-year-old Clinton nor 70-year-old Trump have released their official medical records.