Which Herbs Are Toxic to the Liver? Risks, Symptoms, and Safe Use (2025)

A cup of tea won’t wreck your liver. A capsule might. Most people assume “herbal” means gentle. The truth: a short list of plants and concentrated extracts can trigger serious liver injury-sometimes fast, sometimes silently over weeks. You’ll see the names, the real risks, and simple safety rules you can actually use today.

Short answer: several hepatotoxic herbs are on regulators’ watchlists-kava, green tea extract, comfrey, chaparral, germander, black cohosh, pennyroyal oil, greater celandine, He Shou Wu (Polygonum multiflorum), usnic acid-containing products, and some multi-ingredient weight-loss or bodybuilding blends.

You’re likely here to do a few things: figure out which herbs are risky, learn the warning signs, decide if your supplement is safe, know what to do if symptoms hit, and see what’s different in Australia right now.

TL;DR

• Highest concern: kava, concentrated green tea extract (not the drink), comfrey, chaparral, germander, pennyroyal oil, greater celandine, He Shou Wu (Polygonum multiflorum), usnic acid products, and some weight-loss/bodybuilding blends.
• Common pattern: silent for 2-12 weeks, then fatigue, nausea, dark urine, itching, or yellow eyes. Stop the product and get liver tests straight away.
• Tea vs extract: brewed green tea is fine for most; high-dose extracts on empty stomach are the issue.
• Known liver disease, heavy alcohol use, poly-supplement stacks, and “detox/weight-loss” labeling raise risk.
• In Australia, report any suspected side effect to the TGA and tell your GP or pharmacist before starting new supplements.

Herbs that can harm your liver (what to watch, what’s actually risky)

Not every herb is a problem. But a small group keeps showing up in hospital charts and safety alerts from the US NIH LiverTox database, the US DILIN registry, European DILI networks, and the Australian TGA. Here’s plain language on the main culprits and what the patterns look like.

• Kava (Piper methysticum) - Linked to rare but severe liver injury, including acute liver failure. Risk seems higher with non-traditional solvent extracts and high-dose supplements. Traditional water-based kava is safer but not risk-free. If you drink alcohol, skip kava.
• Green tea extract (catechin-rich, EGCG) - The problem is usually concentrated capsules, not brewed tea. Cases range from mild enzyme bumps to severe hepatitis, especially when taken fasting or with weight-loss products. Drinking green tea (the beverage) is generally safe.
• Comfrey (Symphytum spp.) - Contains pyrrolizidine alkaloids that can scar small liver veins (veno-occlusive disease). Many countries restrict internal use; avoid ingesting comfrey.
• Chaparral (Larrea tridentata) - Touted for “detox,” but repeatedly tied to acute hepatitis and liver failure. Avoid.
• Germander (Teucrium chamaedrys) - Once in slimming teas; caused outbreaks of severe hepatitis in Europe. Avoid.
• Pennyroyal oil (Mentha pulegium) - The essential oil is highly toxic to the liver even in small amounts. Never ingest pennyroyal oil.
• Greater celandine (Chelidonium majus) - Reported cholestatic hepatitis (itching, jaundice). If you see it in “liver cleanse” products, pass.
• He Shou Wu / Polygonum multiflorum (Fo-Ti) - Recurrent cause of herbal hepatitis in Asia and the West. Risk may be higher with raw/unprocessed forms and high doses.
• Usnic acid (often in “fat-burners”) - Tied to severe hepatitis and transplant cases. Avoid products listing usnic acid or “lipoic burners” with it.
• Black cohosh (Actaea racemosa) - Case reports of liver injury exist. Causality is debated, and adulteration complicates it. If you have liver disease, use something else for menopausal symptoms.
• Jin Bu Huan (often misbranded TCM analgesics) - Associated with acute hepatitis; labeling can be unreliable.
• Turmeric/curcumin with bioenhancers (e.g., piperine) - Rare cholestatic hepatitis reported in Australia, Europe, and the US, often with enhanced-absorption formulas.
• Garcinia cambogia - Weight-loss supplements with it have been linked to hepatitis, sometimes severe.
• Aloe vera (ingested, not gel on skin) - Rare cases of hepatitis with oral latex-containing products.

How common is this? In big registries, 15-20% of drug-induced liver injury is from herbal/dietary supplements, and the share is growing. The US DILIN cohort reported roughly one in five cases were supplement-related, with a strong weight-loss/bodybuilding signal. European registries and TGA reports echo the pattern. Most injuries are idiosyncratic-unpredictable, not dose-linear-so one person can take a product for months with no issue while another gets sick in weeks.

What symptoms should set off alarms? Think: fatigue that feels “flu-like” without a fever, nausea, loss of appetite, right-upper abdominal pain, dark urine, pale stools, itching, yellowing of eyes or skin. If you notice these while on a new supplement, stop it and get liver tests (ALT, AST, ALP, bilirubin) as soon as possible.

What makes an herb more dangerous?

• Concentrated extracts or “standardized” high-EGCG green tea capsules, not teas.
• “Detox,” “fat-burn,” “pro-hormone,” or “hardcore” marketing-these categories over-index for liver injuries.
• Multi-ingredient blends where you can’t tell the dose of each plant.
• Use on an empty stomach (notably with green tea extract).
• Underlying liver disease, binge drinking, viral hepatitis, pregnancy.
• Mixing with known liver stressors (e.g., high-dose paracetamol, isoniazid, certain antibiotics or antifungals).

Here’s a quick comparative snapshot to help you spot higher-risk products:

Where does this evidence come from? The NIH LiverTox database, the US Drug-Induced Liver Injury Network (DILIN), the European DILI registries, TGA safety updates, and hepatology society guidelines (AASLD, EASL) have documented these signals repeatedly since the 1990s, with several fresh alerts in the last five years.

How to use herbs safely without wrecking your liver

If you want the benefits without the drama, use this playbook. It’s the same advice I’d give a friend heading to the chemist in Sydney.

1. Decide if you even need it. For sleep, try sleep hygiene before kava. For menopausal symptoms, talk with your GP about non-liver-stressing options before black cohosh.
2. Prefer foods and teas over concentrated capsules. Brewed green tea is fine for most people. It’s the high-EGCG capsules that cause trouble.
3. One product at a time. If you add three new supplements and get sick, you’ll have no idea which one did it.
4. Read the label like a detective.
   • Can you see exact milligrams for each herb?
   • Any “proprietary blend” hiding the dose? That’s a red flag.
   • Any words like “detox,” “fat burner,” “hardcore,” “shred”? Move on.
5. Don’t take risky extracts on an empty stomach. Especially green tea extract.
6. Skip if you have liver disease or drink heavily. That includes fatty liver, chronic hepatitis B/C, cirrhosis, or if your ALT/AST were high recently.
7. Check drug interactions. Herbs can nudge enzymes that metabolise meds: anticoagulants, anti-epileptics, statins, TB meds, HIV meds. Your pharmacist can screen this in minutes.
8. Set a stop rule before you start. If you feel unwell or notice dark urine, pale stools, itch, jaundice, or right-side abdominal pain-stop the product and get bloods the same day.
9. Time-box the trial. If it doesn’t help in 4-8 weeks, bin it. Don’t drift into long-term use without benefit.
10. Buy from reputable brands. Look for batch numbers, TGA-listed AUST-L/AUST-R in Australia, third-party testing marks, and a way to contact the company.

Fast heuristics you can remember:

• If it’s for rapid weight loss, bodybuilding, or “detox,” assume higher liver risk until proven otherwise.
• Teas and culinary spices usually beat capsules on safety; extracts concentrate risk.
• Labels hiding doses hide problems.
• Green tea drink = fine; green tea extract on empty stomach = risky.
• Already have liver disease? Get your GP’s okay first, every time.

What if you already took a risky herb?

1. Stop the product now. Keep the bottle for the batch and ingredient list.
2. Watch for symptoms for 2-4 weeks after stopping; some cases declare late.
3. If any red flag shows up, ask your GP or a walk-in clinic for LFTs (ALT, AST, ALP, GGT, bilirubin) and clotting (INR) if you’re unwell.
4. Report the event to the TGA via the online adverse event portal; it helps others.

If you must use a higher-risk herb (say, you’re set on kava):

• Use the lowest effective dose for the shortest time.
• Don’t mix with alcohol or other sedatives.
• Avoid if you’ve had abnormal LFTs, hepatitis, or jaundice before.
• Check for TGA-listed products and avoid solvent-heavy extracts.
• Stop at the first sign of malaise, nausea, dark urine, itching, or jaundice.

Decision guide in plain English:

1. Is the product a single herb you can name and dose? If no, skip it.
2. Is it used for weight loss, bodybuilding, sexual enhancement, or detox? If yes, skip it.
3. Is your liver healthy, and do you drink minimally? If no, talk to your GP first.
4. Is there a safer food/tea alternative that does the job? If yes, use that first.
5. If you still want it: start low, take with food (unless told otherwise), set a 4-8 week stop date, and pre-agree on red flags.

Australian context (quick notes): The TGA lists lower-risk complementary medicines as AUST-L and higher-risk as AUST-R. That’s not a safety guarantee, but it beats no listing. Kava availability has changed over the years here; even when legal to import or sell in certain forms, the medical liver risk remains. Pharmacists in Australia can check interactions and suggest safer alternatives on the spot.

Cheat-sheets, FAQs, and your next steps

10-second label scan checklist

• Does the front say detox, shred, burner, hardcore, pro-hormone? Put it back.
• Is it a multi-ingredient “blend” without clear doses? Put it back.
• Is the form an essential oil meant to be swallowed? Hard no.
• Is there a TGA AUST-L/R number, batch, and a real company name? Better.
• Any of these names: kava, EGCG/green tea extract, chaparral, comfrey, germander, pennyroyal, celandine, Polygonum multiflorum, usnic acid? Pause and rethink.

Red-flag symptoms checklist (act now)

• Yellow eyes or skin
• Dark urine or pale, clay-coloured stools
• New itch without a rash
• Nausea, loss of appetite, or unusual fatigue
• Right upper abdominal pain or tenderness

If you tick any box while on a supplement, stop it and get LFTs the same day. If you feel very unwell (confused, very sleepy, vomiting), go to urgent care.

Examples (real-world swaps)

• Looking for weight loss? Ditch garcinia and usnic acid blends. Prioritise protein at breakfast, a 30-minute brisk walk most days, and a dietitian consult. Evidence beats hype every time.
• Chasing calm? Consider magnesium glycinate, CBT-i strategies for sleep, and a consistent wind-down routine before kava.
• Menopause symptoms? Discuss non-hormonal meds with your GP before black cohosh; some have better safety data and predictable dosing.
• Joint pain? Try topical NSAID gels and physio before high-dose turmeric capsules with bioenhancers.

Mini‑FAQ

• Is plain green tea safe? For most people, yes. The risk signal is with high-dose extract capsules, especially fasting.
• Is milk thistle protective? It’s often used for liver support, but data are mixed. It’s not a shield against bad choices and won’t cancel out a toxic product.
• Can I use herbs if I have fatty liver? Be extra careful. Many people with fatty liver also drink alcohol or take other meds. Run every supplement past your GP or pharmacist.
• How long until the liver recovers after stopping? Mild cases improve within days to weeks; severe cases can take months. Don’t restart the suspect herb, even if you feel better.
• What tests do I need? LFTs (ALT, AST, ALP, GGT, bilirubin). If you’re unwell, also INR. Your GP will rule out viral hepatitis and other causes.
• Can I drink alcohol while on herbs? If the herb has any liver signal (kava, green tea extract, chaparral, etc.), avoid alcohol entirely.
• Are “natural detoxes” good for the liver? No solid evidence. Your liver already detoxes. Most “detox” blends just add risk.
• How do I report a side effect in Australia? Use the TGA’s adverse event reporting portal. Include the product name, brand, dose, dates, and symptoms.

Next steps by situation

• You’re shopping today: Stick to single-ingredient products you can dose. Avoid weight-loss and detox blends. Choose teas or foods when possible.
• You’ve started a new herb in the last month: Set a calendar reminder for a quick self-check in two weeks. If you feel off, stop and get LFTs.
• You have chronic liver disease: Bring your full meds and supplement list to your GP or pharmacist before adding anything new. Ask, “Is there any hepatotoxic signal here?”
• You’re on multiple meds (statins, TB meds, anti-epileptics): Get an interaction screen from your pharmacist. It takes five minutes and can prevent a mess.
• You had liver issues from a supplement before: Avoid that ingredient forever. Your risk of a worse repeat is higher.

Why listen to these warnings? They come from converging sources: the NIH LiverTox database summarises thousands of cases and trials, hepatology societies (AASLD/EASL) set guidance on evaluation and management, and regulators like the TGA flag real-world harm. The pattern is consistent across countries and years, and 2020-2025 reports continue to pin most supplement-related liver injuries on a handful of herbs and weight-loss/bodybuilding mixes.

What to do if things go sideways

1. Stop the product. Don’t taper-just stop.
2. Call your GP or visit a clinic today for LFTs and an exam if you have red flags.
3. Bring the bottle. Batch numbers matter for investigations.
4. Hydrate, rest, avoid alcohol and paracetamol until you’ve had bloods and advice.
5. Report to the TGA adverse event portal; you might help prevent the next case.

One last sanity check: “Natural” isn’t a safety stamp. Herbs are biologically active. Used well, many are fine. Used blindly, a few can land you in hospital. Take the simple wins-food before capsules, clear labels over blends, and a fast stop rule if your body throws you a warning sign.

Sources behind this guide (named for transparency): NIH LiverTox monographs; US Drug-Induced Liver Injury Network cohort analyses; European DILI Registry reports; Australian TGA safety updates (2019-2025); AASLD and EASL guidance on drug-induced liver injury; peer-reviewed case series on kava, green tea extract, chaparral, germander, Polygonum multiflorum, usnic acid, and turmeric with bioenhancers.