Arthur L. Caplan Ph.D. of New York University's Langone Medical Center.(Photo: John Abbott Photography)
(USA TODAY) -- Con artists come in all shapes and sizes. Some even have medical degrees.
Many people fall victim to charismatic quacks when they're at their most vulnerable and desperate, because they or a loved on are seriously ill, says Arthur Caplan, head of the division of bioethics at NYU Langone Medical Center in New York City.
Caplan and other experts offered these tips to spot questionable health providers.
• They claim to have cures no one else knows about.
Science doesn't work that way, says Barrie Cassileth, director of integrative medicine at New York's Memorial Sloan-Kettering Cancer Center.
Science is a team effort, with a cast of thousands, and it's rare for any one person to make a huge discovery alone, says David Gorski, an associate professor of surgery and oncology at the Wayne State University School of Medicine in Detroit. "Science is about coming to consensus," he says.
And even after a great discovery is made, scientists rely on others to replicate their work, to make sure their finding isn't a mistake or fluke.
If a doctor "really had cured thousands of people, then they all ought to be at a convention," Caplan says.
Even when prospects are grim, Caplan says patients fare better with science than voodoo.
"When mainstream medicine says there is nothing more we can do, your best bet is to head into an clinical trial, Caplan says.
• They claim that others are trying to suppress their discoveries.
Some quacks revel in their maverick status.
Efforts to reprimand them, or rein in bad behavior, may only seem to confirm that these bad boys are being persecuted.
But while conspiracy theories abound in the movies, there's no evidence that drug companies, the government or anyone else is deliberately trying to keep people sick, Caplan says.
"If someone says that the mainstream is trying to hide this from you, that should be read as, 'I'm a crook,' " Caplan says.
Adriane Fugh-Berman, an associate professor at Georgetown University and author of a textbook on herbs and supplements, says many quacks try to compare themselves to famous scientists who were also outcasts.
Their argument, she says, is akin to saying, "They laughed at Galileo; therefore, I must be brilliant, because I am shunned by my colleagues."
• They want cash upfront.
Reputable doctors and hospitals charge only for services rendered, Caplan says. They don't ask for deposits.
"If someone says you have to pay upfront, that is suspicious," Caplan says. "What that says is, 'I'm going to Bimini soon, and not with you.' "
• The treatment is only available outside the USA, such as in Tijuana, Mexico.
If treatments are only offered outside the country, that may be because doctors don't want U.S. authorities to shut them down, Cassileth says.
• They make amazing claims.
"If it sounds too good to be true, it probably is," Gorksi says.
Reliable sources of information on alternative therapies can be found at websites run by the American Cancer Society, the National Center for Complementary and Alternative Medicine, the National Cancer Institute and Memorial Sloan-Kettering Cancer Center, which has a section devoted just to herbs and supplements.
The National Institutes of Health has launched a new database of dietary supplements, with information from the labels of 17,000 supplements, along with science-based information about them. The database also has its own app.
• They rely on testimonials.
Personal stories can be extremely misleading, says Gorski, managing editor at the blog Science-Based Medicine.
A handful of success stories may show only a small part of the larger picture, Gorski says. For every few patients who testify that a treatment helped them, there could be dozens or even hundreds who got no benefit, or were even harmed.
"There's almost no limit to how wrong you can be when you're just going by testimonials," says Steven Novella, an assistant professor of neurology at the Yale University School of Medicine and executive editor at Science-Based Medicine.
Both alternative medicine practitioners and big pharmaceutical companies may market their products with cheery testimonials, Gorksi says. But drug companies are also required by the Food and Drug Administration to back up their claims with data.
Instead of personal anecdotes, look for large, rigorous studies published in peer-reviewed medical journals. These can be found for free online at the National Library of Medicine's PubMed.gov database.