Donald Trump often questions whether Hillary Clinton is honest or trustworthy enough to be president. This week, he took up another line of attack: that Clinton is in failing health.

Claims about Clinton's health have circulated for years but have gained new traction recently, in part thanks to a comment by Trump and questions raised by Fox News host Sean Hannity.

They're adding fuel to an online volley of conspiracy theories saying that Clinton's use of stools and pillows as well as stumbles by the candidate are evidence that she is in poor health. On Wednesday afternoon, a story topping the Drudge Report was headlined "MUST SEE: Photos of Hillary Clinton Propped Up on Pillows." The article is largely a collection of photos showing Clinton sitting at various events with pillows situated behind her lower back.

There is no evidence that Clinton is in poor health. In fact, the Clinton campaign points out that her "stamina and focus" allowed her to endure an 11-hour Benghazi hearing and that Trump drew his own share of criticism after a doctor released a letter saying he would be the "healthiest individual ever elected to the presidency."

This week, Trump said this about Clinton's health:

"Importantly, she also lacks the mental and physical stamina to take on ISIS and all of the many adversaries we face — not only in terrorism, but in trade and every other challenge we must confront to turn our great country around."

Trump's supporters online have been trading theories about how healthy the former secretary of state really is. Many of the questions about Clinton's health center on a 2012 incident. Back then, suffering from a stomach virus, Clinton fainted and suffered a concussion. After that, she was diagnosed with a blood clot.

That incident is being linked to a June video of Clinton acting startled after a sudden barrage of reporter questions.

On Fox News, Hannity has in the past week questioned Clinton's reaction, calling it a "violent, violent repetitive jerking of the head." He and members of a medical panel said that this could be aftereffects from Clinton's earlier concussion and blood clot.

However, a July 2015 letter from Clinton's personal physician, Lisa Bardack, addressed Clinton's December 2012 concussion and blood clot, saying that the concussion symptoms "resolved within two months" and that all symptoms cleared up in 2013. They also said she was put on anticoagulants "as a precaution."

The Clinton campaign has responded by accusing Trump of "peddling deranged conspiracy theories in a desperate attempt to change the subject" from other issues, like the fact that he hasn't released his tax returns.

They also released a statement from Bardack this week, in which she pushes back against claims that Clinton is unwell, as well as false medical records that have been circulating online:

"As Secretary Clinton's long time physician, I released a medical statement during the campaign indicating that she is in excellent health," she said. "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."

AP reporter Lisa Lerer, one of the people questioning Clinton in the above clip, wrote an opinion piece emphasizing that she was not scared and that it did not look like a seizure.

"Where I saw evasiveness, they see seizures," Lerer said of people questioning Clinton's health, adding that it has been two months since the incident but it is only now becoming an issue.

Hannity and his medical panel called for Clinton to release her medical records to clear up the matter. Aside from casting doubt on Clinton's health, the accusations play into a larger narrative of Clinton as secretive and untrustworthy.

The allegations about Clinton's health do not all directly point to the concussion and blood clot. Other videos and photos have been used together to depict Clinton as frail. Many commenters on Twitter (often using the hashtag #HillaryHealth) point to Clinton's trips and falls that have been caught on tape.

Another photo showing Clinton being helped up the stairs at a February event after she had slipped pops up often in tweets suggesting Clinton is ill. However, as Snopes pointed out, there are several other images proving that Clinton can indeed climb stairs without assistance.

A related hashtag that has popped up, #HillarysStools, highlights rallies and speeches where Clinton is given a stool to lean or sit upon onstage.

The questions about Clinton's health are not at all new. As far back as 2013, Trump was questioning Clinton's health, as Politico reported. And in 2014, Republican strategist Karl Rove suggested that Clinton was "wearing glasses that are only for people who have traumatic brain injury" and had stayed in the hospital for 30 days — claims that PolitiFact rated false.

As for Trump's health, in December, the campaign released a letter from Harold N. Bornstein, a doctor of gastroenterology at Lenox Hill Hospital in New York. The letter revealed that Trump, who at 70 is 16 months older than Clinton, takes daily aspirin and a statin, a type of drug used to treat high cholesterol.

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