Herb Profile

Milk Thistle Silybum Marianum

Silybum marianum

Milk Thistle (Silybum marianum) is traditionally used for liver support, with its flavonolignan complex silymarin studied for antioxidant, anti inflammatory, and hepatoprotective activity.

Last reviewed: 4 sources citedReport a correctionProfile-wide ·B Moderate

Use extra caution Generally safe; mild GI upset; possible allergic reactions Details

Evidence
Moderate Evidence
Typical onset
Varies by prep
Safety rating
Moderate caution
Best for
Antioxidant, Liver Protective, Stress resilience, Inflammatory signaling
Avoid / review if
Ragweed Allergy, CYP/Transporter Effects Reported In Vitro, Clinically Significant Interactions Not Well Established
Milk Thistle Silybum Marianum monograph visual
The Hippie Scientist

At a glance

From this profile's structured data
Evidence
Grade B
Safety
Generally safe; mild GI upset; possible allergic reactions
Profile context
antioxidant, liver-protective
Next steps

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Safety

Safety & Cautions

Generally safe; mild GI upset; possible allergic reactions

Elevated caution

Caution level: Elevated. One caution category applies — read it before use.

  • Liver-SensitiveLiver-related caution language appears in the profile.
Detailed safety fields

Pregnancy, breastfeeding, and contraindications

  • Ragweed Allergy
  • CYP/Transporter Effects Reported In Vitro
  • Clinically Significant Interactions Not Well Established

Safety classifications

  • Liver-Sensitive: Liver-related caution language appears in the profile.

Full safety note

  • Generally safe; mild GI upset; possible allergic reactions

Safety labels

  • Liver-Sensitive

Evidence

Evidence Summary

Evidence lens

Useful signal, but study design, dose, and population still matter.

ModerateModerate Evidence

Human clinical evidence: Present in source signals

Mechanistic / preclinical: Mechanism mappedOxidative Stress Modulation · Cellular Protection · NF KB Modulation

Research maturity: Established researchLong Term Human Evidence May Be Limited.

Safety boundary: Safety note availableGenerally safe; mild GI upset; possible allergic reactions

This profile cites 4 human studies.

Study design details
Evidence Grade

Grade B: Moderate Evidence

Evaluation of methodological rigor, population reach, and evidence alignment.

Design Match
Meta-analysis
Risk of Bias
Low
Consistency
Consistent
Strongest recorded design is a meta-analysis, drawn from 9 recorded studies, 6 in people. No disagreement is recorded across them.
How evidence grades work

Each grade reflects the strength and consistency of published human evidence — not marketing claims. Grades are based on study count, design quality, effect size, consistency, and recency.

Strong
Multiple RCTs, consistent direction, adequate effect size
Moderate
Some RCTs or consistent observational data in humans
Preliminary / Mixed
Animal or in-vitro only, or conflicting human data
Traditional / Theoretical
Traditional use only; no controlled human trials
Clinical Study Summaries (8)5 human evidence sources · 2 human trials · ~99 participants across 1 human evidence source with reported N · Consistency not yet classifiable

Filter by study class

Showing 8 of 8 studies.

What the evidence actually shows

This table contains 8 structured sources, including 5 human evidence sources; 2 are human trials. Across 1 human evidence source with a reported sample size, the approximate participant total is 99; overlapping publications may include some of the same people.

StudyDesignNDoseDurationPopulationOutcomeResult & magnitudeSource

Are alterations needed in Silybum marianum (Silymarin) administration practices? A novel outlook and meta-analysis on randomized trials targeting liver injury

Background
Meta-analysis

Statistically combines results from multiple eligible studies; confidence still depends on the quality, consistency, and directness of those studies.

Silymarin significantly reduced AST and ALT in pooled randomized evidence, while ALP did not significantly improve.PubMed

A meta-analysis of 13 randomized trials (915 participants) found no convincing high-quality evidence for clinically important liver-disease outcomes. Study quality and heterogeneity were major limitations.

Background
Meta-analysis

Statistically combines results from multiple eligible studies; confidence still depends on the quality, consistency, and directness of those studies.

A meta-analysis of 13 randomized trials (915 participants) found no convincing high-quality evidence for clinically important liver-disease outcomes. Study quality and heterogeneity were major limitations.PubMed

The effects of silymarin consumption on inflammation and oxidative stress in adults: a systematic review and meta-analysis

Background
Meta-analysis

Statistically combines results from multiple eligible studies; confidence still depends on the quality, consistency, and directness of those studies.

Silymarin reduced CRP, IL-6, and MDA, while IL-10, total antioxidant capacity, and glutathione did not clearly improve.PubMed

A Randomized Trial of Silymarin for the Treatment of Nonalcoholic Steatohepatitis

PubMed · Clin Gastroenterol Hepatol · 2017

Background
Randomized controlled trial

Randomly assigns participants to interventions or controls, reducing many sources of bias when the trial is conducted well.

n=99PubMed

PMID 40733088

Background
Randomized controlled trial

Randomly assigns participants to interventions or controls, reducing many sources of bias when the trial is conducted well.

A 2025 randomized double-blind crossover PK trial in 16 healthy adults found a micellar 130-mg silymarin formulation produced about 18.9-fold higher Cmax and 11.4-fold higher 24-hour AUC than a standard product. No adverse events were observed in this small single-dose study. Higher exposure is not evidence of superior clinical efficacy.PubMed

Milk thistle (Silybum marianum): A concise overview on its chemistry, pharmacological, and nutraceutical uses in liver diseases

Abenavoli L et al. · Phytother Res · 2018

Background
Narrative review

Summarizes selected literature without the full prespecified search and selection methods of a systematic review.

PubMed
Show 2 more studies

Safety and toxicity of silymarin, the major constituent of milk thistle extract: An updated review

Soleimani V et al. · Phytother Res · 2019

Background
Narrative review

Summarizes selected literature without the full prespecified search and selection methods of a systematic review.

PubMed

Milk Thistle

PubMed indexed authors · 2006

Background
Narrative review

Summarizes selected literature without the full prespecified search and selection methods of a systematic review.

PubMed

Dosing & Timing

Dose guidance
Standardized extract (70 80% silymarin): 140 420 mg/day in divided doses; variability in silybin content
How Milk Thistle Silybum Marianum works

Simplified mechanism pathway based on preclinical and pharmacological evidence. Does not confirm clinical efficacy.

Mechanism Pathway — How Milk Thistle Silybum Marianum Works

How Milk Thistle Silybum Marianum WorksMilk Thistle Silybum Marianum acts on biological target pathways via antioxidant, leading to antioxidant efct.Milk Thistle Silybum MarianumBiological TargetBiological pathwayAntioxidantAntioxidant EfctCell protectionCellularProtection
CompoundTarget / ReceptorMechanismEffect / Outcome
Mechanisms & biological pathways (preclinical)
  • Oxidative Stress Modulation
  • Cellular Protection
  • NF KB Modulation
  • Nrf2 Activation

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Recommendation status

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Product form & quality guidelines

When sourcing Milk Thistle Silybum Marianum, verify the label for:

  • Standardized extract: Confirm active content percentages on the supplement facts panel (e.g. standardized to specific marker compounds) rather than simple raw herb weights.
  • Third-party testing: Look for independent purity labels (USP, NSF, ConsumerLab, or Eurofins) to ensure the product is free from heavy metals, solvents, and contaminants.
  • Form bioavailability: Ensure the form matches evidence-supported configurations (e.g. standardized active extracts like bacosides, withanolides, or curcuminoids) for optimal onset and digestion tolerance.

Safety first · Harm reduction

This information is educational and not medical advice. Start low, avoid risky combinations, and consult a licensed clinician before making health decisions—especially if you use medications, have diagnosed conditions, or are pregnant/breastfeeding.

Learn how we evaluate confidence, safety, and intensity on the methodology page.

Editorial Review

Checked against primary sources, cited evidence, and contraindication language before publication. Evidence claims, safety language, and affiliate modules are reviewed independently. Not personal medical advice.

Editorial Standards →

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