People turn to herbal supplements for all kinds of reasons-better sleep, less stress, clearer skin, or just because they sound natural. But here’s something most don’t ask: are herbs toxic to the liver? The answer isn’t yes or no. It’s more like, ‘It depends.’ Some herbs are safe for most people. Others? They can quietly damage your liver without warning. And you might not even know it until it’s too late.

Herbs aren’t always safe just because they’re natural

There’s a big myth out there: if it’s natural, it’s harmless. That’s not true. Think of it this way-poison ivy is natural. Belladonna is natural. Both can kill you. Herbs are complex chemical mixtures. They don’t come with warning labels like prescription drugs. And your liver? It’s the main organ that filters everything you swallow, including herbs.

Studies show that herbal supplements are linked to over 20% of all cases of drug-induced liver injury in the U.S. and Europe. In one 2023 review of liver injury cases in the UK, nearly 1 in 5 were tied to herbal products. These weren’t rare or extreme cases. They were people taking turmeric capsules, green tea extract, or kava for anxiety-all things you can buy at your local health store.

Which herbs are most likely to hurt your liver?

Not all herbs carry the same risk. Some have been studied enough to know their dangers. Here are the top offenders:

• Kava - Used for anxiety and relaxation. Linked to dozens of liver failure cases worldwide. Banned in several European countries.
• Green tea extract - The concentrated form (capsules or powders), not the brewed tea. High doses can cause severe liver damage. At least 100 cases reported globally since 2010.
• Black cohosh - Popular for menopause symptoms. Multiple case reports of acute hepatitis after use.
• Comfrey - Contains pyrrolizidine alkaloids, which are directly toxic to liver cells. Even topical use can be risky if absorbed through skin.
• Chinese skullcap - Often mixed into multi-herb formulas. Contaminated or mislabeled versions have caused outbreaks of liver injury.

And here’s the catch: many supplements don’t even list what’s in them. A 2024 study tested 12 popular liver-supporting herbal blends. Three of them contained undeclared liver-toxic herbs. One had aristolochic acid-a known carcinogen banned in the EU since 2001.

How does a herb damage your liver?

Your liver breaks down everything you take in. It uses enzymes to turn substances into forms your body can use or get rid of. But some herbs interfere with this process. They can:

• Overload liver enzymes, causing them to burn out
• Trigger an immune reaction that attacks liver cells
• Block bile flow, leading to buildup of toxins
• Contain heavy metals or pesticides from poor farming practices

Some people are more sensitive. If you’re on other medications-like statins, antidepressants, or birth control pills-your liver is already working hard. Adding herbs can push it past its limit. Even if you feel fine, liver damage can be silent. No pain. No jaundice. Just rising liver enzymes on a blood test.

Who’s at highest risk?

You might think only older adults or people with existing liver disease are at risk. But that’s not the whole picture.

• Women - More likely to develop herb-induced liver injury than men, especially between ages 30 and 60.
• People taking multiple supplements - Mixing 3 or more herbs increases risk by 4x.
• Those with pre-existing liver conditions - Even mild fatty liver disease makes you more vulnerable.
• People using high doses or long-term use - Taking green tea extract daily for 6 months? That’s not a ‘cleanse.’ It’s a potential hazard.

One woman in her 40s from London started taking ashwagandha and turmeric capsules for ‘stress relief.’ After 8 months, she felt tired and nauseous. Her doctor found her liver enzymes were 8 times higher than normal. She stopped the herbs. Within 3 months, her liver returned to normal. No permanent damage-but she came close.

What should you do before taking herbal supplements?

Here’s a simple checklist you can follow before buying any herb:

1. Check the label - Look for third-party certifications: USP, NSF, or ConsumerLab. These test for purity and accurate dosing.
2. Know the dose - More isn’t better. Stick to the lowest effective dose. If the label says ‘take 3 capsules daily,’ that might be too much.
3. Don’t mix - Avoid combining herbs with prescription drugs unless your doctor says it’s safe.
4. Watch for symptoms - Unexplained fatigue, dark urine, yellow eyes, nausea, or abdominal pain? Stop the herb and see a doctor immediately.
5. Get a liver test - If you’ve been taking herbs for more than 3 months, ask your GP for a basic liver function test. It’s a simple blood draw.

And here’s a hard truth: most herbal supplement companies don’t test for liver safety. The FDA doesn’t require it. In the UK, the MHRA only steps in after people get hurt. You’re the first line of defense.

What about traditional herbal medicine?

Systems like Ayurveda, Traditional Chinese Medicine (TCM), or Native American herbalism have been used for centuries. That doesn’t mean they’re risk-free. Some traditional remedies contain lead, mercury, or arsenic. Others use herbs known to be hepatotoxic, like certain species of Senecio or Petasites.

If you’re working with a traditional practitioner, ask them: ‘Is this herb tested for liver safety? Do you know of any cases where it caused liver injury?’ If they don’t have an answer, walk away.

Alternatives to risky herbs

You don’t need to give up natural remedies entirely. Some options have strong safety data:

• Milk thistle - Often used to support liver health. Evidence suggests it may help protect the liver, not harm it. But don’t take it if you’re allergic to ragweed.
• Probiotics - For gut and immune support, they’re safer than most liver-targeting herbs.
• Regular exercise and sleep - These are the most proven ways to support liver function naturally.
• Reducing alcohol and sugar - These are far bigger threats to your liver than any herb.

Instead of chasing herbal fixes, focus on lifestyle. Your liver doesn’t need more chemicals. It needs rest, clean food, and time to heal.

Final thoughts: Herbs aren’t the enemy-but ignorance is

Herbs aren’t inherently bad. Many have real benefits. But treating them like harmless candy is dangerous. The liver doesn’t scream when it’s hurt. It whispers. And if you ignore the whisper, it can stop working.

If you’re taking herbal supplements, you owe it to yourself to know what’s in them. Ask questions. Get blood tests. Talk to your doctor. Don’t assume ‘natural’ means ‘safe.’

Next steps if you’re taking herbs

If you’re currently using herbal supplements:

• Write down every herb and supplement you take-name, dose, how long you’ve been using it.
• Book a blood test with your GP to check liver enzymes (ALT, AST, bilirubin).
• Stop any herb that’s not backed by solid safety data-especially if you’re unsure why you’re taking it.
• Replace risky herbs with proven lifestyle changes: sleep better, move more, eat less sugar.

Your liver doesn’t need more herbs. It needs you to stop treating it like a garbage disposal.