After her near collapse in public Sunday, Hillary Clinton is now seeing the collapse of her once healthy lead against Donald Trump in the polls. She should release a full medical history, leaving no single question on the table -- or she should leave the race. It’s time to come clean or quit.

For an ordinary candidate, riding out the rumors and recovering might be good enough, but not for one as vulnerable as Clinton. She can, and will most likely, stay on this course, providing minimal information about her health. But Clinton risks further deterioration of her standing that has resulted from voter disgust with her deception over her emails, her foundation and now her illness. The focus will remain on her health, no matter what she says or does. She will be risking defeat.

Yet sharing it all, and putting to rest the deep doubts now circulating among voters and nervous Democratic Party officials, could allow Clinton to begin to reverse the damage her secrecy has done, while also putting Donald Trump on the defensive. He doesn’t want to tell his whole health story either. Clinton should release as much as possible, even if there is something embarrassing involving the female anatomy. The dividends that doing so would pay are worth it.

It isn’t just Republicans who are asking “Is it only pneumonia?” If that is all that ails Clinton she should prove it. After all, that would explain the coughing and hoarseness and dehydration that caused her to go limp in the arms of staff and Secret Service agents outside a 9/11 memorial event in New York. The dramatic video is frightening, and has led to numerous conspiracy theories about strokes, seizure disorders and even the prospect that the campaign trots out a body double every now and then. Top Clinton staff now concede they activated the fever swamp by refusing to reveal the pneumonia diagnosis until the candidate nearly fell in the street. It was the quintessential self-inflicted secrecy wound -- a staple of HillaryLand, and of the candidate herself.

The truth, for non-conspiracists, is that Clinton has already had serious medical problems. She suffered a concussion from a fall, followed by a blood clot in 2012 -- two brain events that temporarily affected her memory. It’s fair to ask if Clinton is at a higher risk for blood clots in the future. Perhaps not, because she takes a blood thinner, but it would be good to know for sure.

As Clinton returns to the campaign trail after three days at home, she should be balancing bed rest and debate preparation with time on her feet at rallies to prove she is “fine” and strong enough to keep up with Trump. There won’t be a second chance for Clinton in the next 50 or so days. Another cough, a bad belly, even a sniffle, would all be amplified and the impact likely explosive. If voters know she’s all right, however, they will overlook days between now and Nov. 8 when she doesn’t seem at her best.

Neither candidate, either of whom will become the oldest president we’ve had, are stepping up to tell us just how fit they are to endure the most grueling job, one that ages you like no other. Trump’s summary of his physical passed muster but was only a snapshot of his health right now; it told nothing of his past, whether he has had heart trouble or other problems. The letter from Clinton’s doctor spoke about her health in the last year, of her newly diagnosed pneumonia and an ear infection, but it most definitely did not speak to her past health challenges or risk of new ones.

If Clinton were to tell all about her health, it will not only make it harder for Trump to keep his medical history private but his tax returns as well. In that case, the transparency-averse Clinton would have handed over both while Trump released neither.

Clinton doesn't find this fair, but total disclosure can turn the tide of her campaign’s stumble while treading water could end it all. She can eliminate much of her problem, or she can exacerbate it. If Clinton can’t admit there is something truly worrisome about her health, she must, for the sake of her party, step down and hand the nomination to someone else.

Democrats should urge Clinton now to cough it up.