Milk Thistle

Early plant records

A 2021 review of silibinin research states that Theophrastus (fourth century BC), Dioscorides (about 50 AD) and Pliny the Elder (first century AD) were the first to report medicinal uses of milk thistle fruits. The review says Dioscorides, in De Materia Medica, described the plant as a remedy for snakebite and for melancholic depression, which it says was then believed to be a liver complaint. It adds that the plant was used in the Middle Ages as an antidote for liver toxins and was included by Renaissance naturalists in their herbal medicine.

These are second-hand statements in a review focused on cancer research. The sources reviewed for this page do not reproduce the early texts, and they do not describe German phytotherapy or other regional histories in detail, so the dates and uses above should be read as that review's account.

Extract research and the hospital preparation

A 2010 review describes the active complex as a lipophilic extract of the seeds, made up of three isomer flavonolignans (silybin, silydianin and silychristin) known together as silymarin, with silybin forming 50 to 70 percent of it. The 2021 review states that over the last 40 to 50 years silymarin extracts have been documented in use for several liver disorders and have become one of the most frequently sold dietary supplements for hepatitis and cirrhosis in the United States and Europe.

A separate line of use is an intravenous pharmaceutical form. A 2024 review of mushroom-related liver failure states that Legalon SIL is a pharmaceutical formulation of silibinin (silibinin-C-2',3-dihydrogen succinate) and that silibinin is listed by the US Food and Drug Administration for Amanita phalloides poisoning through an emergency approval process. That review is the source for this status, and the sources reviewed do not give a full regulatory history.

Plant, extract and constituents

Milk thistle is the common name for Silybum marianum, a member of the Asteraceae (daisy) family. Silymarin is the main constituent mixture of the seed extract, composed of flavonolignans, and silybin is its most active component according to a 2010 review. A 2019 safety review uses the same description. Other common names include Marian thistle and St. Mary's thistle.

The compound is spelled silybin in some papers and silibinin in others, and the literature also uses silibinin for the intravenous preparation. The terms milk thistle, silymarin and silibinin are therefore not interchangeable: they describe a plant or extract, a mixture, and a single compound or drug.

Hepatoprotective and galactagogue

Hepatoprotective is the term reviews use for the claimed liver-protecting action of silymarin, a claim that the trials discussed below test. Galactagogue is the term for a substance used to support milk production, and a 2016 review of botanicals for women's health lists milk thistle among the natural galactagogues used by lactating women.

Supplement products

The National Center for Complementary and Integrative Health (NCCIH) describes milk thistle as a tall purple-flowered plant native to Europe, whose extract is marketed as a dietary supplement, with silymarin as the main component. The NCCIH page states that some supplements have contained silymarin amounts that differ from the label, and some have contained contaminants such as pesticides, microorganisms or mycotoxins. Product content can therefore differ from one brand to another.

The Cochrane review included trials of milk thistle or its constituents at any dose or duration, which means the trials did not test a single standard product. This page gives no doses and does not recommend any product.

Intravenous silibinin in hospital

In suspected Amanita phalloides poisoning, silibinin is one of several measures described in a 2024 review, alongside rehydration, activated charcoal, extracorporeal purification, N-acetylcysteine and, for acute liver failure with poor prognostic features, liver transplantation. The review reports that silibinin is experimentally thought to inhibit uptake of the mushroom toxin into liver cells. This is delivered by hospital teams and poison services, and it is a different setting from taking a supplement.

Liver disease

Reviews state that silymarin has been used for alcoholic liver disease, acute and chronic viral hepatitis and toxin-induced liver disease. Proposed mechanisms include antioxidant action, antifibrotic activity and blocking toxin binding to liver cells; the 2010 review reports the injury-reduction findings it cites for several toxins in animals rather than in people.

A trial paper from 2012 opens by noting that silymarin is commonly used by patients for chronic liver disease despite scant and conflicting evidence of efficacy, and the Cochrane review frames milk thistle as an intervention that randomized trials have tested against placebo or no intervention. These statements describe how widely the product is used, not what it achieves.

Other uses

Milk thistle is also used as a galactagogue, and trials have examined silymarin for fatty liver disease and for insulin resistance in type 2 diabetes. The 2016 review notes that rigorous safety and efficacy studies of milk thistle as a galactagogue are lacking.

Alcohol-related and viral liver disease

The 2007 Cochrane review by Rambaldi and colleagues included 18 randomized trials in 1,088 patients with alcoholic and/or hepatitis B or C liver disease. Methodological quality was low, with 28.6 percent of trials reporting high-quality characteristics. Milk thistle had no significant effect on mortality, complications of liver disease or liver histology. Liver-related mortality was lower across all trials, but not in the high-quality trials. The authors concluded that the results question beneficial effects and highlight the lack of high-quality evidence.

A 2008 systematic review of 19 blinded trials found scarce evidence of an effect in toxic liver disease and no evidence of a favorable influence on viral hepatitis, particularly hepatitis C. In mostly alcoholic cirrhosis, total mortality did not differ significantly from placebo, while liver-related mortality was 10.0 percent with silymarin and 17.3 percent with placebo.

The hepatitis C trial

A multicenter, double-blind, placebo-controlled trial (Fried and colleagues, 2012, JAMA) enrolled 154 people with chronic hepatitis C whose earlier interferon-based therapy had failed and who had raised ALT levels. Silymarin was given at two dose levels, both above customary doses, for 24 weeks. Only 2 participants in each group met the primary outcome, and ALT change, viral RNA levels and quality of life did not differ significantly from placebo. Adverse events were comparable with placebo. NCCIH lists a hepatitis C study among two NCCIH-funded studies that found no benefit.

Fatty liver, diabetes and lactation

A 2023 meta-analysis of 26 randomized trials in 2,375 people with NAFLD or NASH reported lower ALT, AST and lipid levels and improved steatosis on liver histology with silymarin; its authors said confirmation is needed. NCCIH reports that an NCCIH-funded study of a form of fatty liver disease found no benefit. A 2025 meta-analysis of six trials in 673 people found a small improvement in HOMA-IR but no effect on fasting insulin, and no effect in the NAFLD subgroup; its authors called the evidence limited.

For lactation, the 2016 review lists milk thistle as a natural galactagogue but states that rigorous safety and efficacy studies are lacking. The sources reviewed do not report controlled trial results on milk production.

Amanita poisoning and overall quality

A 2022 systematic review of 877 reported amanitin poisoning cases from 131 publications found 59 percent survival with supportive care alone and 90 percent with silibinin alone. In the subset of cases with amanitin detected, the review observed no statistical differences between treatments. The evidence is case reports and series, not randomized trials. A 2026 review describes a conditional recommendation for intravenous silibinin in guidelines for acute liver failure from mushroom poisoning, graded as very low quality evidence.

NCCIH summarizes the liver-disease literature as conflicting or too limited for firm conclusions. Evidence from poisoning, an acute hospital setting, does not carry over to chronic liver disease or supplement use.

Reported adverse effects and interactions

NCCIH states that milk thistle taken by mouth appears to be well tolerated, with bloating, nausea and gas the most common effects. It may cause allergic reactions, especially in people allergic to related plants in the daisy family such as ragweed and chrysanthemum. The Cochrane review found no significantly increased risk of adverse events versus placebo or no intervention.

A 2019 safety review reports mainly gastrointestinal discomfort such as nausea and diarrhea, low drug interaction potential and no major effects on cytochrome P-450 enzymes. It still advises caution with narrow-therapeutic-window drugs and during pregnancy. NCCIH says little is known about use in pregnancy or breastfeeding and advises anyone taking medicine to talk with a health care provider first.

Who should involve a clinician

Liver disease is a medical condition that needs diagnosis and monitoring. The trials above do not support using milk thistle in place of conventional care, and any use alongside it is best raised with the treating clinician. Suspected mushroom ingestion is an emergency, because a 2024 review describes delayed symptoms followed by severe liver injury, and people who may have eaten wild mushrooms need urgent medical attention or a poison service. This page is information only and gives no advice for any individual.