TAMPA, Fla. — Hillary Clinton addressed conspiracy theories about an allergy attack she had on Monday with humor — and an extra dose of antihistamines.

“The advice, of course, is just don’t talk for a day or two,” she told reporters on a Tuesday flight to campaign events in Tampa. “Yeah, that’s not going to happen. Not going to happen.”

Mrs. Clinton, the Democratic presidential nominee, struggled to get through an outdoor Labor Day rally in Cleveland on Monday when she was struck by a coughing attack. The spell took on a life of its own in conservative media, where alarming tales about Mrs. Clinton’s health have long been bubbling.

Kellyanne Conway, the campaign manager for Donald J. Trump, the Republican nominee, used the coughing to accuse Mrs. Clinton of a lack of transparency, saying she “must be allergic to media.”