“It is possible to work with brands and still remain fact-based and science-based,” she said, but she acknowledged that “part of it is necessity — because debunking was taking up so many of my hours.”

Ms. Wong quit her job in 2019 to devote herself full-time to Lab Muffin Beauty Science, but she still sometimes works up to 70 hours per week. “Science just takes so much longer than misinformation, because you have to do the research properly,” she said.

Once a debunker has an audience, the work of maintaining and building an account can also lead to burnout. Like most influencers, they put pressure on themselves to excel. As Dr. Austin Chiang, a gastroenterologist with over a half-million TikTok followers, explained, they often blame themselves if their content underperforms. “We think, is it because my messaging isn’t good?” he said. “Is it because the quality of the video isn’t good?”

Dr.. Wallace said the most exhausting element, though, was the harassment. Commenters repeatedly insult her, and when she posts in favor of vaccination, they accuse her of being a “shill for Big Pharma.” “I block accounts every day,” Dr.. Wallace said. She also received threatening and sexually violent messages through her university email account — a situation that she said had required the university police to become involved early this year.

For health care professionals, harassment can also lead to professional consequences, or the fear of them. “Many people’s institutions don’t want them to be attracting tons of negative attention,” said Renée DiResta, a misinformation expert and the technical research manager at the Stanford Internet Observatory, which studies internet propaganda. Doctors are encouraged to treat patients. Scientists are encouraged to conduct research and submit their findings for peer review. To create content on TikTok? Less so.

Mr. Dhahir considered quitting TikTok after users found the address of his pharmacy and spread rumors about his professional and personal lives. He also had to meet with the dean of medicine at the University of Sydney and explain why the university had received complaints. Mr. Dhahir said he felt supported by his university but worried that that could change quickly. “One wrong move, and then my work can fire me or the university can kick me out,” he said. “I have to make sure I don’t screw up.”