Herbal Products and Liver Injury

Herbal products and dietary supplements (a cause of herb-induced liver injury, HILI)

Green tea extract capsules, high-bioavailability turmeric/curcumin, kava, comfrey and other pyrrolizidine-containing herbs or “bush teas”, ashwagandha, bodybuilding and fat-burning products, and mixed herbal blends from herbal shops (attar). These are examples of product types, not a complete list.

Drug-induced liver injury (DILI) is liver damage caused by a medicine, herb or supplement; when an herb or supplement is the cause it is called herb-induced liver injury (HILI). The liver processes almost everything we swallow, and some herbal compounds, contaminants (for example heavy metals) or hidden drugs can injure it. Injury is usually unpredictable (idiosyncratic) and not simply related to dose. Diagnosis is by exclusion: doctors rule out viral hepatitis, alcohol, fatty liver, autoimmune and bile-duct disease, then look at the timing of the product. The ACG 2021 guideline on idiosyncratic DILI and the EASL 2019 clinical practice guideline on DILI describe this approach, and both stress taking a careful history of every herb and supplement, with the product label. In the US DILIN network, herbal and dietary supplements now account for roughly one in five confirmed DILI cases, and bodybuilding supplements and green tea extract are among the leading causes. LiverTox (a free NIH database) rates the likelihood of liver injury for individual products. Pyrrolizidine alkaloids in comfrey and some bush teas can damage the small veins in the liver (sinusoidal obstruction syndrome). Kava has been restricted in several countries after liver failure cases. Concentrated green tea catechin extracts raised liver enzymes in trials and the European Food Safety Authority (EFSA, 2018) judged them a concern at higher intakes (drinking normal green tea is not the issue). Ashwagandha and high-bioavailability turmeric have been linked to cholestatic or hepatocellular injury in case series. Milk thistle is often taken “for the liver”, but there is no good evidence it treats liver disease.

The safest approach is to avoid herbal and “detox/liver tonic” products unless your doctor agrees, especially if you have liver disease. If you do use a product: use only one at a time, buy an SFDA-registered product with a full ingredient list, avoid unlabelled mixtures from herbal shops, follow the label and your doctor’s or pharmacist’s advice, and tell every doctor about it. Keep the original packaging. Do not take herbal products together with medicines that can affect the liver (for example some antibiotics, anti-tuberculosis drugs, paracetamol in high amounts) unless your doctor has checked. Do not assume a long history of traditional use makes a concentrated extract safe. WHAT TO DO if you notice warning signs: STOP the product, call your doctor the same day (go to the emergency department if you are very unwell), bring the product and all packaging, and give a full list of everything you took and when you started. Doctors will do blood tests (ALT, ALP, bilirubin, INR) and look for other causes. Do not restart it, even if you feel better.

• Yellow eyes or skin (jaundice) — A key sign of liver injury. Stop the product and see a doctor urgently the same day.

• Dark (tea or cola-coloured) urine, pale or clay-coloured stools — May show bile is not draining properly. See a doctor urgently.

• Severe itching, persistent nausea or vomiting, loss of appetite, extreme fatigue, or pain in the upper right belly — Possible liver injury. Stop the product and contact your doctor the same day for blood tests.

• Confusion, extreme sleepiness, vomiting blood, black stools, easy bruising or bleeding, or a swollen belly — May indicate acute liver failure or complications of cirrhosis. This is an emergency: go to the emergency department or call emergency services now.

• Swollen belly, painful liver, and weight gain after drinking herbal “bush tea” or comfrey — Could be damage to the liver’s small veins from pyrrolizidine alkaloids. See a doctor urgently.

Herbal products can add to the liver burden of medicines and can change how the liver processes them. Examples: St John’s wort lowers levels of many drugs (see our article on supplement and medicine interactions), and several herbs affect the blood levels of tacrolimus and other transplant medicines. Combining several products, alcohol, paracetamol overuse, anti-tuberculosis therapy, some antibiotics and anabolic steroids raises the risk. Contaminated products (heavy metals) or products containing hidden prescription drugs can also harm the liver. People with cirrhosis or chronic hepatitis B or C, fatty liver or a liver transplant should discuss every herb or supplement with their liver team before starting.

If you use a product in a higher-risk group, ask your doctor about baseline and follow-up liver tests (ALT, ALP, bilirubin). Doctors may use the LiverTox database and a standard causality assessment (such as RUCAM) to judge whether a product caused the injury. Most people improve after stopping, with blood tests repeated until normal; some need hospital care, and rarely a liver transplant. Report suspected cases to the SFDA.

Stop immediately at the first warning sign and do not restart the product or similar ones without your doctor’s permission. Stop all non-essential herbal products if your liver tests rise unexpectedly. Never stop prescribed medicines for your liver disease on your own.

Avoid herbal products and supplements in pregnancy and breastfeeding unless your doctor or midwife agrees. Many herbs have not been tested for safety in pregnancy, and comfrey and other pyrrolizidine-containing herbs are unsafe.

Herbal remedies and mixed “attar” blends are widely used in Saudi Arabia for the stomach, weight, strength and “liver cleansing”, often recommended by family, shops or social media. Blends from herbal shops may be unlabelled, inconsistent, or contaminated, and their contents are hard for doctors to trace; ask the seller for the full ingredient list and keep the packaging. Hospital reports from the region describe herbal and traditional remedies among causes of liver injury. Report suspected harm to the SFDA National Pharmacovigilance Centre (unified number 19999 and the SFDA website). In Ramadan, avoid starting new herbal “detox” products, especially with fasting and dehydration.

• Is any herbal product I take on the list of those linked to liver injury?

• Do I need liver blood tests now, since I take (or took) a herbal product?

• I have hepatitis or cirrhosis: are there any herbs or supplements that are safe for me?

• Can you help me report a suspected reaction to the SFDA?

This guide comes from the Saudi Gastroenterology Association (SGA) patient library, prepared by the Approved for publication by SGA; individual clinician review is ongoing. Last reviewed: 2026-04-24. It is for education and does not replace your doctor's advice.