"She has pneumonia and, well, you know, it's curable," Reid said flatly at a news conference. "She's off the campaign trail for a few days. She probably needed the rest anyway. So you folks have magnified it."
He urged reporters to turn their lenses to Trump's health instead.
"Take a look at this character that's running for president. He complains about her health. What does he do? He's 70 years old. He's not slim and trim. He brags about eating fast food every day. Look at his health a little bit," Reid said.
Reid's frustration arose after several days of intense news coverage of Clinton's illness after she felt ill at a ceremony marking the 15th anniversary of the 9/11 attacks. She was escorted out and the press pool that covers her was in the dark about her whereabouts and medical condition for several hours.
All aspects of the Democratic presidential nominee's recent coughing fits, possible fainting spell, and eventual diagnosis of pneumonia were reported above the fold in the major newspapers and treated as "breaking news" on many television networks.
Her campaign's lack of disclosure and handling of her health woes also have been poked and examined by editorial boards and panels of pundits.
"You've all been unfair to Hillary," Reid complained, further noting that she had "submitted a multiple-page report from a doctor -- a good doctor -- talking about what medicine she's on. Pretty thorough."
Trump hasn't submitted medical reports, just as he hasn't released details of his charitable giving or his tax returns, Reid said.
"I can't imagine you folks not being a little inquisitive about what he's done to cheat people in Atlantic City and everywhere," Reid said.
Reid, who is 76 and retiring this year after 30 years in the Senate, predicted that regardless of the negative attention Clinton is getting on the health issue, she will win the White House.
"And we're going to have a Democratic Senate," he added.