Rudy Giuliani says Hillary Clinton has a secret illness. His supposed proof? Online videos.

Rudy Giuliani has joined the chorus of Donald Trump supporters peddling conspiracy theories about Hillary Clinton’s health.

“She doesn’t need to campaign,” the former New York City mayor, who has emerged as one of the Republican nominee’s most visible surrogates, said on “Fox News Sunday.” “She has the New York Times, she has the [New York] Daily News, she has ABC, she has CBS, she has NBC. She has an entire media empire that constantly demonizes Donald Trump and fails to point out that she hasn’t had a press conference in 300 days — 200 days, 100 days, I don’t know how long — and fails to point out several signs of illness by her.”

Fox News host Shannon Bream noted that the Clinton campaign has said “there’s nothing factual” to claims about her health.

“All you’ve got to do is go online,” Giuliani replied. “Go online and put down ‘Hillary Clinton illness’ and take a look at the videos for yourself.”

The irony of Giuliani, the mayor of New York City during the Sept. 11, 2001, terror attacks, citing Internet videos to prove a conspiracy theory was not lost on some viewers.

The Clinton campaign has pushed back against conspiratorial claims about her health in recent days after fake medical records for the former secretary of state surfaced on right-wing websites.

“As Secretary Clinton’s longtime physician, I released a medical statement during the campaign indicating that she is in excellent health,” Lisa Bardack said in a statement released by the Clinton campaign on Thursday. “I have recently been made aware of allegedly ‘leaked’ medical documents regarding Secretary Clinton with my name on them. These documents are false, were not written by me and are not based on any medical facts. To reiterate what I said in my previous statement, Secretary Clinton is in excellent health and fit to serve as President of the United States.”

The same day on MSNBC, Trump national spokeswoman Katrina Pierson diagnosed the Democratic nominee as having “dysphasia,” a neurological condition caused by a brain injury resulting in partial or complete impairment of the ability to communicate using speech.

Pierson’s proof: “Observations” of Clinton’s “behavior and mannerisms” made by viewers of out-of-context video clips circulated online.

MSNBC host Kristen Welker read Bardack’s statement on air, but Pierson was undeterred.

“It is extremely important to note that Hillary Clinton has taken a lot of time off the campaign trail,” Pierson said. “It is something that needs to be addressed.”

Last week, Fox News host Sean Hannity hosted a segment dedicated to speculating about Clinton’s health by breaking down online videos, including one that showed Clinton rocking her head back and forth in mock surprise to rapid-fire questions from reporters at a campaign stop.

“I saw the same video you saw,” Fox News medical correspondent Marc Siegel said, “and I’m wondering about a word called ‘aphasia,’ where you’re searching for words, you suddenly lose those words, and that can be the sign, again, of some kind of traumatic brain injury or the aftereffects of a concussion.”

Amy Kremer, a co-founder of Women Vote Trump, suggested Clinton, who suffered a concussion in 2012, is suffering from chronic traumatic encephalopathy or CTE — a condition that several former NFL football players were diagnosed with after their deaths.

“The NFL has had major lawsuits from players getting concussions years ago,” Kremer said on CNN Sunday.

“Hold on,” CNN’s Poppy Harlow interjected. “Are you comparing Hillary Clinton’s health and the state of her brain to an NFL player who has a serious concussion after multiple hits?”

Trump himself has made veiled references to Clinton’s health, saying in an Aug. 16 speech on national security that she “lacks the mental and physical stamina” to be commander in chief. He made a similar remarks on Saturday in Virginia.

The Clinton campaign slammed Trump’s comments as a subterfuge.

“While it is dismaying to see the Republican nominee for president push deranged conspiracy theories in a foreign policy speech, it’s no longer surprising,” Jennifer Palmieri, the Clinton campaign’s communications director, said in a statement. “Donald Trump is simply parroting lies.”