Can Supplements Damage Your Liver?

Herbal supplements account for a rising share of the serious liver injury cases that reach specialist registries, and the ingredients most often implicated include several sold specifically for liver health. Serious supplement-associated liver injury appears uncommon — but it is real, and a supplement is not required to clear the evidence bar a medicine does before it reaches the shelf.

TL;DR

• Supplements rose from 7% to 20% of cases in the main US liver injury registry across a decade, reaching 130 of 839 adjudicated cases. That's a share of severe liver injury, not a risk estimate for supplement users.
• Transplantation was more common in the supplement cases — 13% of non-bodybuilding supplement cases underwent transplantation against 3% of medicine cases. Mortality alone was not significantly different.
• Exposure is widespread. In a US survey of 9,685 adults, 4.7% had taken one of six botanicals flagged for liver risk, turmeric most of all.
• Green tea extract has one of the largest bodies of published cases. UK advice is that up to 800 mg a day of EGCG — the catechin, not the extract — is probably safe, while accepting that unpredictable reactions can't be excluded at any dose.
• Turmeric reactions are rare but can be serious. Liver problems are reported "very rarely", and trials show no organ toxicity — but where injury occurs it isn't trivial.
• Ashwagandha should be avoided if you already have a liver disorder — that is an explicit regulator instruction, issued in July 2026.
• UK supplements are regulated as food, not medicine. Sellers are legally responsible for safety, but ordinary supplements don't need the pre-market authorisation or clinical trials a licensed medicine does.

How often are supplements behind serious liver injury?

The clearest data comes from the US Drug-Induced Liver Injury Network, which has tracked serious cases prospectively since 2004. In its published analysis of 839 adjudicated cases, 709 were attributed to conventional medicines and 130 — 15.5% — to herbal and dietary supplements. The supplement share rose from about 7% in the registry's first two years to 20% a decade later, a statistically significant increase.

That number is easy to misread, so it's worth being precise about what it isn't. It does not mean 15.5% of supplement users suffer liver injury. DILIN is a network of specialist referral centres collecting the most serious cases from a very large population, so the figure describes the composition of severe liver injury, not the risk attached to taking a supplement. Serious injury remains uncommon in absolute terms.

The same study does record a difference in outcomes, stated carefully. Among patients referred to the network with liver injury, those whose injury was attributed to non-bodybuilding supplements underwent liver transplantation more often than those whose injury was attributed to conventional medicines — 13% against 3%, a difference that held after adjustment. On the network's severity score, 35% of those cases were classed severe or fatal against 26% for medicines. Mortality alone was not significantly different, at 4% against 7%, and none of the 45 bodybuilding-supplement cases died or underwent transplantation. All of which describes a selected clinical population, and cannot establish that taking a supplement is generally more dangerous than taking a medicine.

How many people are taking them

A 2024 analysis in JAMA Network Open put numbers on the exposure side using US national survey data from 9,685 adults. Supplement use was close to universal — 57.6% had taken one in the previous 30 days — and 4.7% had taken at least one of the six botanicals that recur most often in liver injury cases: turmeric or curcumin, green tea extract, Garcinia cambogia, black cohosh, red yeast rice and ashwagandha. Turmeric led by a distance, reported by 236 participants, followed by green tea at 92 and ashwagandha at 28. These aren't obscure products; they're the front of the shop.

The paper's framing drew criticism from herbal-sector bodies, who argued that calling six widely-used botanicals "potentially hepatotoxic" implies a risk that exposure data cannot demonstrate. That has force — this study counted who was taking what, not who came to harm. The useful point is the combination: millions of people taking ingredients that turn up disproportionately in the worst cases.

Green tea extract: the most implicated single ingredient

Green tea extract has one of the largest bodies of published cases among the botanicals in this article. A US Pharmacopeia expert review analysed 75 cases of associated liver injury, concluding that severe hepatotoxicity can result and identifying the catechin EGCG as the likely cause. Most affected people were taking between 500 and 3,000 mg of extract a day.

The UK's Committee on Toxicity examined the same question and published a statement in 2024 that is more measured than the coverage around it. Reviewing the European assessment, it concluded that up to 800 mg a day of EGCG is probably safe, with no new evidence to change that. It also noted that injury has been reported with one product containing 375 mg, and that an unpredictable individual reaction cannot be excluded at any dose — a different kind of risk from a simple threshold.

Both bodies draw the same line, and it's the line most consumers don't know exists. Ordinary brewed green tea has not been associated with the pattern of liver injury seen with concentrated extracts. A capsule is a different product: many times the dose you'd get from drinking it, with other components of the leaf stripped out, and taking it on an empty stomach increases how much EGCG reaches the liver.

One practical trap on the label. The 800 mg figure refers to EGCG, not to green tea extract, and products state one, the other, or both. A capsule listing 800 mg of extract is not the same as one delivering 800 mg of EGCG, so the number worth finding is the catechin content.

Turmeric: rare reactions, occasionally serious consequences

Turmeric is the most widely used of the implicated botanicals, and the evidence on it points in two directions at once. The US Pharmacopeia published a comprehensive review in Pharmaceutical Biology in June 2026 and reached a restrained conclusion: liver problems have been reported "very rarely" in people taking turmeric or curcuminoid supplements.

The detail behind that phrase matters in both directions. Numerous clinical trials of these supplements have not reported organ toxicity or serious adverse events, and the reviewers note that published case reports often involve other medicines or supplements taken alongside, which complicates attribution. But where injury does occur it is not trivial: it typically appears after one to four months, generally resolves when the supplement is stopped, and acute liver failure has been reported, albeit rarely. The reviewers recommended a cautionary label rather than withdrawal.

The useful distinction is between frequency and severity: the frequency of injury appears very low, while the severity in a susceptible individual can be substantial. Emerging evidence points to genetic susceptibility, which would explain why millions take turmeric uneventfully and a handful don't — and why turmeric in food is a different proposition from a concentrated daily capsule.

Ashwagandha: one clear instruction

Ashwagandha is the ingredient where a regulator has said something specific and recent. On 7 July 2026 Australia's Therapeutic Goods Administration published a safety update reporting that liver injury cases continue to be reported both domestically and internationally, and its advice includes a line that matters for anyone reading a liver article: products containing it should be avoided by people with existing liver disorders.

The scale is worth stating plainly, because the TGA itself calls the risk very rare. No fatalities or transplants have been reported in Australian consumers. Following an earlier alert, four cases required hospitalisation, with most resolving once the product was stopped. Internationally the regulator points to at least four published reports of liver failure including one transplant, and to three deaths reported by researchers in India — all in patients who already had acute-on-chronic liver failure, taking single-ingredient preparations. The Netherlands pharmacovigilance centre has reported twelve cases up to June 2025, with onset ranging from six weeks to twenty-two months.

The clinical picture is well documented. A case series in Liver International describes five patients, mean age 43, who all developed jaundice with nausea, lethargy and itching after two to twelve weeks. None developed liver failure and four recovered within one to five months — though four were also taking other supplements, which is the recurring difficulty in attributing any of this.

Two other details from the TGA are practically useful. Sudden gastrointestinal symptoms have been reported and can be mistaken for food poisoning. And several of the cases it received involved products bought online from overseas, outside any regulator's quality controls.

Why supplement regulation differs from medicine regulation

In the UK, most food supplements are regulated as foods by the Food Standards Agency rather than as medicines by the MHRA. Manufacturers and sellers are legally responsible for the safety of what they sell, so this isn't an unregulated market. What ordinary supplements don't require is the pre-market authorisation and clinical evaluation expected of a licensed medicine — as NHS guidance puts it, manufacturers "are not required to prove the safety or efficacy of their products before placing them on the market".

So a product being legally on sale tells you nothing about whether its claimed benefits have been demonstrated. Supplements also aren't held to pharmaceutical manufacturing standards: undeclared ingredients may be present, batch-to-batch variation can be significant, and once on sale a supplement isn't proactively monitored the way a licensed medicine is.

There is a middle category most people have never noticed. Traditional herbal medicines registered under the THR scheme must meet specified safety and quality requirements and are monitored like medicines, but their permitted uses rest on traditional use rather than demonstrated efficacy. They carry a THR number, which an ordinary supplement does not. It isn't proof that something works; it does tell you someone has checked how it was made.

What This Actually Means

Serious supplement-associated liver injury appears uncommon, and its shape is more useful than its size. It is usually reversible when the product is stopped, and appears to depend on individual susceptibility rather than a dose dangerous to everyone. Nobody needs to panic about a turmeric capsule. Supplements also fail in a second, quieter way: a 2025 Cochrane review of 17 trials and 2,069 participants found insufficient reliable evidence to establish whether milk thistle improves important clinical outcomes in fatty liver disease — not harmful, simply unestablished.

What deserves attention is the overlap. Several ingredients that recur in the case literature are marketed for liver support and weight loss, so the products a worried reader reaches for first are among those most often named in reports. That isn't a comparative risk calculation between shop shelves — nobody has done one — but it is a reason to weigh an uncertain benefit against a small real possibility of harm. The things that do help, as our Liver Reset sets out, are cutting alcohol, eating less ultra-processed food and moving more, none of which comes in a bottle.

Three practical points. If you already have any liver condition, the regulator's instruction on ashwagandha applies to you specifically, and the same caution is sensible for concentrated extracts generally. Multi-ingredient products make problems almost impossible to trace — four of five patients in that case series were taking something else too. And if you take any supplement regularly, say so when you have blood tests, because this kind of injury is easy to miss when nobody has asked.

Frequently Asked Questions

Which supplements are most linked to liver damage?

Six recur in the case literature: turmeric or curcumin, green tea extract, Garcinia cambogia, black cohosh, red yeast rice and ashwagandha. Weight-loss and bodybuilding formulations also appear repeatedly. Green tea extract has the largest body of cases.

Is green tea bad for your liver?

Brewed green tea isn't implicated. The concern is concentrated extract in capsules, where the dose is many times higher. UK advice is that up to 800 mg a day of EGCG is probably safe, though unpredictable individual reactions can't be excluded.

Is ashwagandha safe?

For most people the risk appears very rare, and no deaths or transplants have been reported in Australian consumers. But Australia's regulator advises avoiding it if you have an existing liver disorder, and the deaths reported internationally were in people who already had liver failure.

What are the warning signs?

Jaundice, dark urine, pale stools, persistent nausea, unusual tiredness, itching or pain in the upper right abdomen. Stop the suspected supplement, seek prompt medical advice, and keep the packaging so a clinician can review the ingredients. Confusion, marked drowsiness, vomiting blood or rapid deterioration needs emergency care. Don't stop a prescribed medicine without clinical advice. In documented cases symptoms appeared after weeks or months rather than days.

Does milk thistle protect your liver?

Nobody knows. A 2025 Cochrane review of 17 trials and 2,069 participants found insufficient reliable evidence to establish whether silymarin improves important clinical outcomes in fatty liver disease. That's uncertainty, not a demonstrated absence of benefit.

The Bottom Line

Supplements are a recognised cause of serious liver injury, their share of cases in the main registry tripled over a decade, and among patients who reach a specialist network those cases more often end in transplantation. In the UK, sellers are responsible for safety, but no one has to demonstrate before marketing that a supplement works or that it has been through clinical evaluation.

That isn't an argument for fear, and the registry numbers are not a personal risk estimate. It is an argument for weighing a small but real chance of serious harm against benefits that, for most of these products, nobody has established. If you already have a liver condition, that calculation is not close.

This article is for general information and is not medical advice. If you develop jaundice, dark urine, pale stools or persistent unexplained symptoms after starting a supplement, stop the suspected product, keep the packaging and seek prompt medical advice from your GP. Do not stop a prescribed medicine without clinical advice.

Sources

• Navarro VJ, Barnhart H, Bonkovsky HL, et al. Liver injury from herbals and dietary supplements in the U.S. Drug-Induced Liver Injury Network. Hepatology, 2014;60(4):1399–1408. https://doi.org/10.1002/hep.27317
• Likhitsup A, et al. Estimated exposure to 6 potentially hepatotoxic botanicals in US adults. JAMA Network Open, 2024;7(8):e2425822. https://doi.org/10.1001/jamanetworkopen.2024.25822
• Committee on Toxicity. Statement on the hepatotoxicity of green tea catechins (COT 08/2024). Food Standards Agency, 2024. https://doi.org/10.46756/sci.fsa.wii944
• Oketch-Rabah HA, et al. United States Pharmacopeia comprehensive review of the hepatotoxicity of green tea extracts. Toxicology Reports, 2020.
• Rarely reported cases of hepatotoxicity associated with turmeric- and curcuminoid-containing dietary supplements: a comprehensive review by USP. Pharmaceutical Biology, 2026;64(1):866–901. https://doi.org/10.1080/13880209.2026.2693375
• Withania somnifera (Ashwagandha) and very rare risk of liver injury. Medicine Safety Update, Therapeutic Goods Administration, 7 July 2026. https://www.tga.gov.au/news/safety-updates/withania-somnifera-ashwagandha-and-very-rare-risk-liver-injury
• Björnsson HK, Björnsson ES, Avula B, et al. Liver injury due to ashwagandha: a case series from Iceland and the US Drug-Induced Liver Injury Network. Liver International. https://pmc.ncbi.nlm.nih.gov/articles/PMC8041491/
• Wang C, et al. Silymarin for adults with metabolic dysfunction-associated steatotic liver disease. Cochrane Database of Systematic Reviews, 2025. https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD015524.pub2/full
• Understanding food supplements. NHS Specialist Pharmacy Service. https://sps.nhs.uk/articles/understanding-food-supplements/