6 Supplements That May Be Damaging Your Liver

As the largest internal organ, the liver carries out hundreds of vital functions that keep your body running smoothly. It is responsible for filtering toxins out of the blood, processing key nutrients, producing bile for fat digestion and metabolizing medications and foreign compounds. However, when it’s overloaded with harmful substances, it becomes vulnerable to inflammation and injury. Supplements, in particular, often contain high concentrations of compounds that can strain this hardworking organ. While they are often seen as a natural way to support health, experts caution that the six supplements below should be taken carefully to avoid potential liver damage.

1. Green Tea Extract

Green tea extract is widely sought after for its antioxidant and heart-protective properties, but concentrated supplements may do more harm than good. “Green tea extract (EGCG or epigallocatechin gallate) capsules can harm the liver at high doses,” says Vanessa Rissetto, M.S., RD, CDN. She explains that concentrated EGCG can generate immune reactions and oxidative stress in susceptible people, leading to liver inflammation and irritation that mirrors hepatitis. Instead, she recommends reaching for brewed tea, as it has much lower concentrations of EGCG. But if you prefer supplementation, she says, “keep EGCG from supplements 300 milligrams or less per day and avoid products delivering 800 mg or greater per day, which have been linked to liver enzyme elevations and injury.”

2. Vitamin A

Vitamin A plays an essential role in vision, immunity, skin health and cellular growth, but too much can quickly turn toxic—particularly when taken in supplement form. The type most likely to cause harm is retinol, the active form of vitamin A, which is often found in high doses in supplements. Unlike water-soluble vitamins that flush out the body easily, says Tara Durden, M.S., RDN, vitamin A is a fat-soluble vitamin that tends to build up in the liver when intake exceeds the body’s needs. She warns that when the liver becomes overburdened with vitamin A, it increases the risk of toxicity. As such, she recommends sticking to the safe dose of 1,000 to 5,000 IU per day and avoiding high doses greater than 10,000 IU to reduce the risk of acute vitamin A toxicity.

3. Niacin

Niacin, also known as vitamin B3, is often taken to manage high cholesterol. However, high doses can take a huge toll on the liver. “At nutritional levels, niacin is safe, but pharmacologic doses used for cholesterol (often 1 to 6 grams per day) can inflame the liver and cause jaundice,” says Rissetto. She highlights that sustained-release niacin supplements pose the highest risk. “Even supplements containing 500 mg or more can raise liver enzymes [a marker of liver stress or damage] in some users, and the risk climbs with grams-per-day dosing or switching formulations without supervision,” she emphasizes. For these reasons, the tolerable upper intake for adults is 35 mg or less per day. Rissetto cautions that prescription-strength use or any dose of 1,000 mg per day or more should only be taken under the guidance of a clinician.

4. Ashwagandha

Ashwagandha is a popular herbal supplement promoted for its stress-relieving and anxiety-reducing benefits. Although generally considered safe for short-term use, recent reports have linked some commercial herbal products claiming to contain ashwagandha to rare cases of liver injury. There have also been rare cases of liver injury and, in some instances, the need for a liver transplant in people with preexisting liver diseases and cirrhosis. The exact cause of liver toxicity is unknown, but some experts suspect that compounds in ashwagandha called withanolides are the main culprit. Typical amounts found in supplements range from 150 to 600 mg, taken one to three times per day. However, Durden recommends using the lowest effective dose. She also advises only taking the supplement for a short period of time, choosing third-party tested brands and seeking medical attention if symptoms of liver injury appear.

5. Kava

Kava is an herbal supplement that is typically used to promote relaxation and ease anxiety. However, depending on the dose and how it’s formulated, its calming effects can come at a serious cost to liver health. “Kava products, especially solvent extracts, have been tied to severe liver injury, including rare cases of liver failure,” warns Rissetto. She points out that these effects may be due to the herb’s toxic metabolites or its ability to deplete the liver’s antioxidant defenses. The risk of liver injury is even higher when the herb is taken with alcohol or other compounds that may harm the liver or if you have preexisting liver disease. To reduce the risk of liver damage, Rissetto recommends choosing water-extracted formulations made from the root of the plant, not exceeding 240 to 250 mg of kavalactones per day and only taking them short-term.

6. Black Cohosh

Though black cohosh is marketed as a natural remedy for menopause symptoms, such as hot flashes, night sweats and mood regulation, it doesn’t come without risk. “Black cohosh has been associated with idiosyncratic hepatitis [drug-induced liver injury] and, rarely, liver failure,” says Rissetto. She notes that the specific compound responsible for the effects on the liver isn’t known, so people with liver disease should avoid it, and any user who experiences adverse symptoms should stop taking the herb immediately. If you do choose to take black cohosh, she outlines that clinical studies often involve around 40 mg of extract daily. However, the safety of long-term use is uncertain, so it’s best to use the supplement on a short-term basis and pay close attention to any symptoms that may arise.

Signs and Symptoms of Liver Damage

If you’re taking any of the above supplements, both dietitians advise that you stop the supplement immediately and contact your health care provider if you notice the following signs and symptoms:

• Jaundice: Yellowing of the skin or whites of the eyes
• Dark urine: Particularly if it appears brown or like cola in color
• Pale stools: White or gray stool is a sign of reduced bile flow
• Abdominal pain or discomfort: Especially if it’s in the upper right side of your abdomen
• Nausea, vomiting or loss of appetite: Seek medical attention if these symptoms persist
• Itchy skin: This can be a sign of bile or toxin buildup
• Fatigue: Especially if it’s profound or prolonged
• Easy bruising: This occurs when your liver stops producing enough clotting factors that stop bleeding.

“Some people have no early symptoms, so blood test abnormalities (ALT/AST, bilirubin, INR) after starting a supplement also warrant stopping and evaluation,” adds Rissetto. Of all of the symptoms, Rissetto emphasizes that in drug- or supplement-induced liver injury, jaundice signals more severe disease and needs prompt attention.

Our Expert Take

Many people turn to supplements to boost their immune, mental, hormonal and overall health. However, herbal remedies and high-dose nutrients aren’t as harmless as they may seem. Supplements like vitamin A, niacin, green tea extract, kava, ashwagandha and black cohosh should be taken with caution, as they have all been linked to liver injury, inflammation and damage when taken in excess. 

Though the liver works tirelessly to filter out excess substances, it still has its limits. When those limits are crossed, symptoms like yellow skin and eyes, dark urine, fatigue, nausea, vomiting, loss of appetite, pale stools and itchy skin can arise. If you experience any of these symptoms, experts advise stopping supplementation and seeking medical attention immediately. After all, your body’s largest internal organ is counting on you to adhere to professional guidance and proper dosages to prevent long-term damage.