Supplement analysis backed by scientific evidence · PT · ES · DE · FR

← All supplements
Limited evidenceGeneral health

Milk Thistle (Silymarin)

Despite decades of use as a "liver protector," milk thistle has repeatedly failed its best-designed trials: a Cochrane review found no mortality or histology benefit in alcoholic and viral liver disease, and two well-run NASH trials missed their primary endpoints. The intravenous silibinin used for death-cap mushroom poisoning is a different, hospital-only product.

View on iHerb Ships to 180+ countries · welcome discount for new customers

What the science says

  • Improves outcomes in alcoholic or viral liver disease Limited evidence

    A Cochrane systematic review of 13 randomized trials (915 patients) found milk thistle did not significantly reduce all-cause mortality, liver-related mortality, complications or histology in alcoholic and/or hepatitis B or C liver disease; apparent benefits were confined to trials at high risk of bias. This is the strongest evidence available and it is negative.

  • Treats non-alcoholic steatohepatitis (NASH) Limited evidence

    A 48-week randomized trial of silymarin 700 mg three times daily in biopsy-proven NASH failed its primary endpoint (a ≥30% reduction in NAFLD activity score) but showed improvement in fibrosis stage in a secondary analysis. A separate NIH-funded phase 2 trial (420 or 700 mg three times daily for 48-50 weeks) also did not meet its histologic primary endpoint. Network meta-analyses of natural products in NAFLD rank silymarin among the better-studied options, but with low certainty.

  • Lowers liver enzymes (ALT/AST) Moderate evidence

    Across NASH and drug-induced liver injury trials, silymarin fairly consistently produces modest reductions in ALT and AST. Whether an enzyme change without histologic or clinical improvement matters to patients is unresolved — the NASH trials showed you can get one without the other.

  • Antidote for Amanita (death cap) mushroom poisoning Moderate evidence

    Intravenous silibinin dihemisuccinate is used in Europe and under US expanded-access protocols for amatoxin poisoning, supported by large observational series rather than randomized trials. Oral milk thistle supplements have far lower bioavailability and are not a substitute.

Dosage & safety

Studied doseTrials used 280-2,100 mg/day of silymarin, most commonly 140 mg three times daily of an 80% standardized extract; the NASH trials went as high as 700 mg three times daily for 48 weeks. Silymarin is poorly absorbed; silybin-phosphatidylcholine complexes improve bioavailability several-fold at lower milligram doses.
SafetyGenerally well tolerated; the main effects are a mild laxative action, nausea and bloating. Allergic reactions occur in people sensitive to the Asteraceae family (ragweed, chrysanthemum, marigold, daisy). Silymarin inhibits CYP2C9 and UGT enzymes in vitro and may raise levels of warfarin, some statins and diabetes drugs — clinically significant interactions are uncommon but reported. It may lower blood glucose, adding to antidiabetic drugs. Data in pregnancy are inadequate. Using milk thistle as "liver cover" for alcohol or hepatotoxic drug use has no evidence base and may delay proper care.

How to take it

TimingTwo or three times a day; timing within the day does not matter.
With food?With a meal containing fat — silymarin is poorly water-soluble and absorbs badly on its own.
Worth knowingA silybin-phosphatidylcholine complex at 200-400 mg delivers more silybin than 1,000 mg of a plain 80% extract, so compare on form rather than milligrams.

Interactions

With medications

  • warfarin

    Silymarin inhibits CYP2C9, the main enzyme clearing warfarin, and may raise INR. monitor INR when starting or stopping

  • insulin, sulfonylureas and other diabetes drugs

    Silymarin may lower blood glucose, adding to their effect. monitor glucose when starting

  • statins metabolised by CYP2C9 (fluvastatin, rosuvastatin)

    Levels may rise, though clinically significant cases are uncommon. mention it to your prescriber rather than stopping either

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does milk thistle protect the liver?

Not in its best trials: a Cochrane review of 13 trials found milk thistle did not reduce mortality, complications or liver histology in alcoholic or viral liver disease, so the evidence is limited. Milk thistle does modestly lower liver enzymes (moderate evidence), but that has not translated into clinical benefit.

Does milk thistle help fatty liver disease?

The evidence is limited: two well-run trials of silymarin in NASH, including 700 mg three times daily for 48 weeks, missed their primary histology endpoints. One showed fibrosis improvement only in a secondary analysis.

Can milk thistle protect my liver from alcohol?

No — using milk thistle as 'liver cover' for alcohol or liver-toxic drugs has no evidence base and may delay proper care.

Does milk thistle interact with medications?

Milk thistle's silymarin inhibits CYP2C9 and may raise INR on warfarin, so monitor INR when starting or stopping. Silymarin may also lower blood glucose on top of diabetes drugs.

Scientific references

Where to buy

California Gold Nutrition, Silymarin Complex, 120 Veggie Capsules

View on iHerb

Ships to 180+ countries · welcome discount for new customers

Referral link — this site may earn a commission on purchases.

Related in General health