Is Milk Thistle Good for Fatty Liver? What Trials Show

TL;DR

• Milk thistle (silymarin) has not been shown to treat fatty liver. The AASLD guidance says it should not be used as a treatment for MASH, and the European guideline cannot recommend supplements like it.
• The best trials found no significant improvement in liver biopsies compared with placebo. One hinted at less scarring, but that was a secondary result and has not been confirmed.
• It is generally well tolerated, but products vary in quality. Tell your doctor before you take it, and put your effort into weight, food and activity instead.

Is Milk Thistle Good for Fatty Liver?

Not in any way that has been proven. Milk thistle is a plant, and silymarin is the extract sold in capsules. People take it for the liver, but when researchers tested it in people with MASH (metabolic dysfunction-associated steatohepatitis, formerly NASH), it did not clearly beat placebo. This article is about MASLD (formerly NAFLD), the most common form of fatty liver, and its inflamed form, MASH.

Two guidelines weigh in. The AASLD 2023 practice guidance lists silymarin among treatments that “should not be used as a treatment for NASH” because they do not offer a meaningful histological benefit (the change seen on a liver biopsy). The 2024 EASL–EASD–EASO guideline notes that silymarin may improve liver enzymes, but that the few small trials did not document improvement on biopsy. It also says nutraceuticals (supplements and herbal products) cannot be recommended for MASLD because there is not enough evidence of their effectiveness or safety.

What Did the Milk Thistle Trials Find?

Two randomized, placebo-controlled trials in people with biopsy-proven MASH are the ones guidelines point to. Both ran 48 weeks.

	Malaysia trial (Wah Kheong, 2017)	US trial (Navarro, 2019)
People	99 adults with biopsy-proven NASH	78 randomized adults without cirrhosis
Dose	Silymarin 700 mg three times a day	Silymarin 420 mg or 700 mg three times a day
Main goal	A fall of 30% or more in NAFLD activity score	A drop of 2 or more points in NAFLD activity score
Main result	32.7% with silymarin vs 26.0% with placebo, not significant	15% (700 mg), 19% (420 mg) vs 12% (placebo), not significant
Other findings	Scarring improved by 1 stage or more in 22.4% vs 6.0% (secondary result)	Many participants did not meet entry criteria on central review

Sources: Clinical Gastroenterology and Hepatology 2017; PLoS One 2019.

The Malaysian authors wrote that silymarin “may reduce liver fibrosis but this remains to be confirmed in a larger trial.” That scarring result was a secondary outcome, which is a reason to test it again, not a reason to start taking it. The US team concluded the effect of silymarin “remains inconclusive,” in part because 63% of participants did not meet the biopsy criteria when a central pathologist reviewed their slides, and because scarring improved most in the placebo group.

Notice also the dose. Those trials used a standardized extract at 1,260 to 2,100 mg of silymarin a day. A shelf supplement may contain a very different amount.

Is Milk Thistle Safe?

In the trials, silymarin was safe and well tolerated at those doses. The National Center for Complementary and Integrative Health (NCCIH) says oral milk thistle appears well tolerated, with bloating, nausea and gas the most common side effects. It also lists:

• Allergy. It may cause reactions in people allergic to related plants such as ragweed, chrysanthemum, marigold and daisy.
• Interactions. It can interact with some medicines, so ask your pharmacist if you take any.
• Pregnancy and breastfeeding. Little is known about safety.
• Quality. Some products contain silymarin amounts that differ substantially from the label, or are contaminated with pesticides, microorganisms or mold toxins. In the US, supplements are not approved by the FDA before sale.

That last point matters for anyone with a liver condition. Your liver processes what you swallow, and the label may not tell you what is in the bottle. For more on how medicines and supplements show up in blood tests, see ALT blood test: high and low levels explained.

Should You Take Milk Thistle for Your Liver?

If you have simple fatty liver, there is no evidence it will help, and the expense is better spent elsewhere. If you have MASH, the guidelines advise against relying on it, and your doctor can tell you which treatments have proof behind them. If you have cirrhosis, ask your hepatologist before taking any supplement; the US trial above was in people without cirrhosis, so it tells us little about you.

If you decide to try it anyway, do it with your doctor’s knowledge:

1. Tell your doctor and pharmacist, and bring the bottle.
2. Do not stop or skip prescribed medicines because you are taking it.
3. Do not count on it to lower an ALT or AST. If your numbers change, ask whether it is the supplement, your diet or your weight (see ALT and AST levels in fatty liver).
4. Stop and call your doctor if you notice yellow skin or eyes, dark urine, itching or unusual tiredness.

What Works Better Than Milk Thistle?

The AASLD says losing 3% to 5% of body weight improves liver fat, but greater loss (more than 10%) is generally required to improve inflammation and scarring. The EASL guideline also puts lifestyle change first. A Mediterranean-style pattern, regular activity and little or no alcohol are the foundation (see how to reverse fatty liver and the fatty liver diet).

Foods are a gentler place to start than capsules. Coffee has some of the best observational evidence (see is coffee good for fatty liver), and the best foods for fatty liver page ranks others by strength of evidence. If you have MASH with moderate scarring, there are now approved medicines to discuss, such as resmetirom.

The Bottom Line

Milk thistle has not been shown to treat fatty liver. The best trials missed their main goals, the guidelines advise against it as a MASH treatment, and supplement quality varies. It is usually well tolerated, so it is not dangerous for most people, but it is not a shortcut. Spend the effort on weight, food, movement and alcohol, and keep your doctor in the loop about anything you take.

Sources

• AASLD Practice Guidance on the clinical assessment and management of nonalcoholic fatty liver disease (Hepatology, 2023)
• EASL–EASD–EASO Clinical Practice Guidelines on the management of MASLD (Journal of Hepatology, 2024)
• Wah Kheong C et al. A randomized trial of silymarin for the treatment of nonalcoholic steatohepatitis (Clinical Gastroenterology and Hepatology, 2017)
• Navarro VJ et al. Silymarin in non-cirrhotics with non-alcoholic steatohepatitis: a randomized, double-blind, placebo controlled trial (PLoS One, 2019)
• NCCIH: Milk Thistle

This article is for informational purposes only and is not medical advice. Talk to your doctor or hepatologist about your specific situation.