4 Supplements That Can Damage Your Liver

Some dietary supplements marketed for energy, liver support, or weight loss may pose serious risks to liver health, according to a June 2026 analysis by EatingWell and corroborated by toxicology reviews in The American Journal of Clinical Nutrition. Four categories—green tea extract, black cohosh, kava, and usnic acid—have been linked to liver damage in clinical cases, with the U.S. Food and Drug Administration (FDA) issuing warnings about two of them since 2023.

The most urgent risk comes from green tea extract, which contains concentrated catechins. A 2024 FDA safety alert cited 13 cases of acute liver injury between 2020 and 2023, including one patient who required a transplant after taking a high-dose supplement. “The problem isn’t green tea itself but the extract in pill form,” said Dr. Andrew Greenberg, a hepatologist at Massachusetts General Hospital, noting that brewed tea’s lower catechin levels pose minimal risk. The FDA advises limiting green tea extract to no more than 800 mg per day, though many products exceed this without clear labeling.

Black cohosh, a herbal remedy often used for menopause symptoms, has been flagged by the European Medicines Agency (EMA) for 11 cases of liver toxicity since 2015. A 2025 study in Hepatology found that black cohosh supplements contain unpredictable levels of triterpenes, compounds that may trigger immune-mediated liver damage. The EMA recommends avoiding the supplement entirely for patients with preexisting liver conditions, a stance the FDA has not yet adopted in official guidance.

Kava, a Pacific Island root used for anxiety relief, presents a different but equally severe threat. The FDA banned kava-containing dietary supplements in 2023 after linking them to 20 cases of liver failure, including three deaths. Unlike the other supplements, kava’s risks are dose-dependent: the banned products contained 200 mg or more of kavalactones per serving, far exceeding the 100 mg threshold where toxicity becomes likely, according to a 2024 review in Drug Safety. “The margin between therapeutic and toxic doses is razor-thin,” warned Dr. Elena Vasquez, a pharmacologist at the University of California, San Francisco.

Usnic acid, found in lichen-derived supplements marketed for weight loss, has emerged as a newer concern. A 2026 case report in Journal of Clinical Gastroenterology described a 42-year-old woman who developed fulminant hepatic failure after taking a usnic acid supplement for six weeks. The FDA has not issued a formal warning, but the supplement’s mechanism—mimicking thyroid hormones to boost metabolism—is known to stress the liver. “This is a classic example of a compound that looks safe in isolation but becomes dangerous when concentrated,” said Dr. Greenberg.

What sets these four apart from other supplements is the consistency of liver injury reports. Unlike occasional adverse events, all four have been tied to multiple cases of hepatitis, jaundice, or liver failure in peer-reviewed studies. The FDA’s Adverse Event Reporting System logged 470 cases of liver-related harm from these supplements between 2018 and 2025, with green tea extract and kava accounting for nearly 60% of severe outcomes. “The pattern is unmistakable,” said Dr. Vasquez. “These aren’t isolated incidents—they reflect a structural risk in the way these compounds are formulated.”

Yet the risks are not evenly distributed. A 2025 survey of 1,200 supplement users published in Journal of the Academy of Nutrition and Dietetics found that 78% of those who experienced liver issues were taking multiple supplements simultaneously, often mixing them with prescription medications. “Drug interactions and additive toxicity are the real villains here,” said Dr. Greenberg. For example, black cohosh can amplify the effects of warfarin, a blood thinner, while usnic acid may interfere with statin metabolism, both increasing liver strain.

The FDA’s approach to mitigating these risks has been cautious. While it has banned kava and issued warnings for green tea extract and black cohosh, usnic acid remains unregulated despite mounting evidence. The agency’s Dietary Supplement Labeling Final Rule, effective in 2023, now requires manufacturers to disclose potential liver risks—but compliance remains uneven, with 30% of tested products failing to list warnings accurately, per a 2026 audit by the Consumer Reports National Research Center.

For consumers, the primary defense is avoiding high-dose or poorly regulated supplements. The Natural Medicines Comprehensive Database, a clinical resource, recommends against green tea extract, black cohosh, and usnic acid for anyone with liver disease or those taking hepatotoxic drugs like acetaminophen. Kava is banned in the U.S. for dietary use, though it remains legal in some European countries under strict medical supervision. “If you’re considering any of these, ask yourself: Is the benefit worth the risk?” said Dr. Vasquez. “For most people, the answer is no.”

What comes next depends on regulatory action. The FDA is reviewing petitions to ban usnic acid, while the EMA has proposed stricter monitoring for black cohosh. Meanwhile, the American Liver Foundation has launched a public awareness campaign targeting supplement manufacturers, urging them to adopt third-party testing for liver toxicity markers. “This isn’t just about individual cases,” said Dr. Greenberg. “It’s about systemic failures in how supplements are developed, marketed, and regulated.”

For now, the safest course remains skepticism. The FDA estimates that 23,000 emergency room visits annually are linked to dietary supplements, with liver injury representing a growing share. “The burden of proof should be on the manufacturer to show safety, not on consumers to prove harm,” said Dr. Vasquez. Until then, she advises sticking to whole foods and consulting a healthcare provider before adding any supplement to a regimen—especially those promising rapid results.