Jimmy Fallon greets Hillary Clinton with a mask, hand sanitizer on 'Tonight Show'

Hillary Clinton visited TheTonight Show Starring Jimmy Fallon on Monday night.

"Welcome, welcome, thank you so much, it is great to have you here," host Jimmy Fallon told the Democratic presidential nominee, while wearing a surgical mask.

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Clinton, who has been the subject of health rumors and who fainted from a spell of pneumonia on 9/11, responded to the bit with a laugh and high-five for the host. Fallon then piled on hand sanitizer.

During the interview, which was taped on Friday, Fallon asked Clinton about the challenges of appearing both friendly and serious while on the campaign trail.

"It's especially tricky for women. It just is," Clinton said, adding that you can't "talk about ISIS with a big grin on your face."

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She continued, "It is a constant balancing act. How to keep the energy and the positive spirit while taking seriously what you need to."

Clinton and her GOP rival Donald Trump have been at odds over their approaches to the war on terror, especially in wake of the weekend's bombings in New York and New Jersey.

Earlier in the night, Trump appeared on The O'Reilly Factor to discuss his stance on racial profiling. The nominee said the U.S. is too politically correct and needs to follow Israel's lead as to how to "successfully" profile potential terrorists."They're getting good public relations because it looks like they're beating the United States," he told the host about ISIS, "or certainly like the United States can't beat them."

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Last week, Trump also appeared on The Tonight Show, and Fallon was subsequently criticized for going too easy on the nominee.

Both Trump and Clinton's appearances come less than two weeks before the first presidential debate that will be moderated by NBC Nightly News' Lester Holt on Sept. 26.

Clinton's full interview aired Monday night at 11:35 p.m. on NBC.