The dietary supplement garcinia cambogia has developed a huge following in recent years thanks in part to an aggressive advertising campaign pitching it as a simple way to lose weight and burn fat. One problem: There’s little if any evidence it actually has those effects. And now there's news that current and potential users might have another reason to avoid the supplement: Garcinia cambogia has been linked to mania, a condition marked by euphoria, delusions, and overexcitement.

The new concern comes from three cases detailed in the journal Primary Care Companion for CNS Disorders, which were reported by Brian Hendrickson, M.D., a psychiatrist at New York-Presbyterian Hospital at Weill Cornell Medical Center in New York City, and his colleagues.

All three of the patients experienced manic episodes after taking unspecified amounts of garcinia cambogia for a month or longer, Hendrickson says. “They all exhibited classic symptoms of mania such as pressured, very fast speech, a decreased need for sleep, and irritability,” he says.

Two of the patients, a 50-year-old man and a 34-year-old woman, had previously been diagnosed with bipolar disorder, a condition that causes unusual shifts in mood, though in both cases the condition had been under control prior to their most recent episodes. The other patient, a 25-year-old man, had no history of psychiatric illness. And in each case, the patients recovered from their manic episodes when they stopped taking the supplements and were treated with prescription drugs such as lorazepam and olanzapine, which are commonly used to treat mania, Hendrickson says.

While far from conclusively proving that garcinia cambogia causes mania, the cases do raise concerns, Hendrickson says.

He theorizes that garcinia cambogia might trigger manic episodes in people with a history of bipolar disorder, and “unmask” the condition in people who are at risk for bipolar disorder but have never experienced symptoms. For example, the 25-year-old man cited in the recent journal article might have been at an increased risk for developing the disorder and the supplement then might have sparked his initial episode.

An earlier study, in the Journal of Medical Toxicology, suggests that garcinia cambogia might have this effect by increasing the amount of serotonin in the brain, a chemical that helps regulate mood. Flooding the brain with excess serotonin could potentially produce “substance induced” manic episodes. Other substances known to trigger mania include antidepressants and anabolic steroids. In those cases, the mania disappears when the offending substance is discontinued.

“It’s possible that mania is a very rare but important side effect of garcinia cambogia and we’re just seeing it in susceptible people now that the supplement is so widely used,” says Stephen Heymsfield, M.D., a professor at Louisiana State University's Pennington Biomedical Research Center and an expert on garcinia cambogia, who was not involved in the current study.

“In this case the authors have congregated a few cases, but it could just be the tip of the iceberg and it will take further study to really investigate if, in fact, this is a serious adverse event,” Heymsfield says.

Not Worth the Risk

This new concern strengthens the case for avoiding garcinia cambogia. “These few cases don't prove that garcinia cambogia causes mania, but it does suggest that some so-called dietary supplements can exert powerful pharmacological effects,” says Consumer Reports’ chief medical adviser Marvin M. Lipman, M.D. “This makes them not worth the risks, proven or unproven.”

Beyond the possible connection to mania, other research has linked the herbal remedy to health problems that include jaundice, elevated liver enzymes, liver damage requiring a transplant, and one death from liver failure.

And data Consumer Reports obtained from the FDA through a Freedom of Information Act request for our earlier investigation in dietary supplements revealed that from January 2015 through May 2016, nearly 100 people experienced adverse events after taking supplements containing garcinia cambogia.

On top of those known and possible risks, there’s little evidence that garcinia cambogia offers users any benefits. Heymsfield, who published the first randomized controlled trial on the effectiveness of garcinia cambogia in JAMA in 1998, says: “There are no credible studies showing that garcinia cambogia causes weight loss in humans.”