Dr. Oz is offering Trump advice for handling the coronavirus. Here are 8 times he's made false or baseless medical claims.

Oz has pushed hydroxychloroquine to fight the coronavirus, even though its effects are still unproven.

On Monday, Oz told "Fox and Friends" that hydroxychloroquine, an antimalarial drug, could be an effective treatment for COVID-19, the disease caused by the coronavirus. Trump is a fan of the drug, calling it "the biggest game-changer in the history of medicine."

"There's no question it's not proven to be beneficial in the large clinical trials we expect in America, and certainly the FDA and medical societies would desire," he said. "But these have been supported with case studies."

Oz cited one French doctor's research on the drug, which found that of 24 patients treated with hydroxychloroquine, 75% were no longer sick after six days.

The French doctor's research was not a peer-reviewed study published in an academic journal. He released the results on YouTube.

According to Dr. Anthony Fauci, the United States' top infectious disease expert, there is nothing but anecdotal evidence that the drug works against the coronavirus, Axios reported.

Most experts are wary of the limited studies that have already been published about the effects of hydroxychloroquine on COVID-19, since they have shown mixed results, and the drug can also cause eye and heart damage.

Oz repeatedly claimed that raspberry ketones are 'the No. 1 miracle in a bottle to burn your fat.'

In a February 2012 episode of his show, Oz touted raspberry ketones, the compound that gives the fruit their smell, as "the No. 1 miracle in a bottle to burn your fat."

One study typically used to justify raspberry ketones as a weight-loss supplement tested eight substances at once, making it "impossible to tell which substances actually contributed to the extra fat loss, and which did nothing," according to the Public Affairs Council, a consumer-awareness resource.

Another test, conducted on rats, found evidence supporting the compound. But the results of a test on laboratory rodents will not necessarily be the same for those done on humans, Melinda Manore, then-professor of nutrition at Oregon State University, told the Los Angeles Times.

"Rats are not humans," the Public Affairs Council said in a statement. "There is a total lack of research on raspberry ketones' effects on fat loss."

Oz has said astrological signs "may reveal a great deal about our health."

In a now-deleted tweet, Oz said astrology could help people understand their personal health.

"For centuries, we have used astrological signs to examine our personality and how we interact with those around us," he said. "However, these signs may reveal a great deal about our health as well."

Astrology is a pseudoscience, and scientists consider the link between it and medicine to be a relic of the time before the scientific revolution.

Oz told viewers that green coffee extract "has scientists saying they've found the magic weight-loss cure."

During an episode of his television show in 2012, Oz suggested that viewers partake in magic beans.

"You may think magic is make-believe, but this little bean has scientists saying they've found the magic weight-loss cure for every body type: It's green coffee extract," he said.

But green coffee extract is not a "magic" cure. It's not a cure at all, according to the Federal Trade Commission, which brought a lawsuit against a Texas-based company that used a "hopelessly flawed" study to support its weight-loss claims about the coffee extract. That study was later cited by Oz on his television show.

"The Dr. Oz Show has since removed nearly any hint of support for Green Coffee Extract from its website," according to Popular Science, "including the full episode devoted to its benefits and Oz's own study of its effects."

The company behind the study agreed in 2014 to pay the FTC $3.5 million and ensure scientific substantiation for any future weight-loss claims it makes.

That same year, Oz testified before the Congressional Subcommittee on Consumer Protection, Product Safety and Insurance about his advertisement of weight-loss products like the coffee extract.

"The scientific community is almost monolithic against you in terms of the efficacy of the three products you called 'miracles,'" former Sen. Claire McCaskill, chairwoman of the subcommittee at the time and a Missouri Democrat, told him.

Oz said most countries require genetically-modified foods to have special labels.

Oz has expressed concerns about genetically modified foods, though scientific studies agree that they're safe.

"I do not claim that GMO foods are dangerous, but believe that they should be labeled like they are in most countries around the world," he wrote in a Facebook post.

But a majority of countries do not require labels, according to the Genetic Literacy Project.

More importantly, the Food and Drug Administration says foods should only be labeled if they threaten health or the environment. Legally mandating labeling, according to the American Association for the Advancement of Science (AAAS), "can only serve to mislead and falsely alarm consumers."

Genetically modified foods "are not likely to present risks for human health any more than their conventional [non-modified] counterparts," the World Health Organization says, and the AAAS maintains that they "pose no greater risk than the same foods made from crops modified by conventional plant-breeding techniques."

He's also said umckaloabo root extract "has been incredibly effective at relieving cold symptoms" even though it isn't.

Oz has touted the health benefits of a little-known root extract from umckaloabo, a plant endemic to South Africa.

"It has been incredibly effective at relieving cold symptoms, and a new study shows it helps the flu," he said in a video city by Live Science.

But "there's a lack of reliable studies on the benefits of these products," the National Center for Biotechnology Information said. "Some studies have shown that ... [herbal products including umckaloabo] can at best slightly relieve a cough."

Oz recommended using lavender soap to cure leg cramps.

"I know this sounds crazy," Oz said on his television show in 2010, "but people put it under their sheets. We think the lavender is relaxing and maybe itself beneficial."

A lavender soap bar may be relaxing, but scientific research does not support Oz's claim that it is "itself beneficial" for leg cramps.

A strawberry-and-baking-soda mixture can whiten teeth, Oz said.

On his television show, Oz proposed an unconventional teeth-whitening method: strawberries and baking soda.

The mixture may be effective at removing plaque, but it does not whiten teeth and may in fact harm tooth health, according to two studies by Dr. So Ran Kwon, a professor of dentistry at the University of Iowa.

"The only benefit of the do-it-yourself method [strawberries and baking soda] is while it seems to make your teeth look whiter, they look whiter because you're just removing plaque accumulation on your teeth," she said in a statement.

"You really want something that penetrates into your teeth and breaks down the stain molecules," she continued. "If you don't have that, you get just the superficial, and not the whitening from the inside, which was what you really want."