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Lexicon
Lexicon

Silymarin (milk thistle)

The best known liver preparation and the one with the weakest evidence - excellently tolerated, but unproven.

3 min read 7 sources

To the sources
Several glossy blue molecule chains of spheres float in two rows above a white podium in a bright lab, symbolic image for the compound mixture silymarin
Traditional use · in the EU only from long use, not from trials

Summary

At a glance

Sources checked on 26 Oct 2026

Goal reached in SyNCH
2 per group

154 people with hepatitis C, 24 weeks, the same number on placebo and both doses1

In the Cochrane review
1,088 patients

18 trials, no significant effect on mortality3

NASH primary goal reached
32.7 %

48 weeks, on placebo 26.0%, difference not significant4

Cirrhosis trial without survival benefit
200 patients

Alcohol-dependent patients, 15 versus 14 deaths, survival the same2

  • Silymarin is a mixture of six flavonolignans from the fruit of the milk thistle. In the lab it showed antioxidant, anti-inflammatory and antifibrotic effects.4
  • The methodologically strongest trials came out negative: in SyNCH only two participants per group reached the goal in hepatitis C, in alcoholic cirrhosis survival was the same.12
  • The Cochrane review of 18 trials with 1,088 patients found no effect on mortality. The benefit on liver-related mortality disappeared once only high-quality trials counted.3
  • Tolerability in the trials was good: side effects overall occurred as often as on placebo, gastrointestinal complaints somewhat more often.13
  • In the EU milk thistle only counts as a traditional herbal medicine, without proof of efficacy from trials. Everything here is the state of research, not a recommendation.6
Profile

Updated July 2026

Class
Plant extract

mixture of six flavonolignans

Use
Oral

2 to 3 times daily with food

Bioavailability
Low

poorly water-soluble

Tolerability
Excellent

side effects at placebo level

Efficacy
Not proven

the best trials came out negative

Contents 12 sections
  1. At a glance
  2. What is silymarin?
  3. How it works
  4. Use and dosing
  5. What the research shows
  6. Research status
  7. Side effects
  8. Storage
  9. Related compounds
  10. FAQ
  11. Glossary
  12. Sources

What is silymarin?

Silymarin is a mixture of six flavonolignans from the fruit of the milk thistle. The most important component is called silibinin. In cell assays it acts as a radical scavenger and is said to stabilise the membrane of the liver cell, so that less toxin gets in.

It is by far the best known liver preparation and at the same time one of the most poorly supported. This page says so openly, because the alternative would be selling you a benefit the studies do not deliver.

This information is for research and educational purposes only. No medical advice.

Comparison

What the lexicon lists for the liver

Entries in the TPD lexicon that relate to the liver, as described there. Tap a card to open its entry.

Plant extract, benefit unproven Silymarin (milk thistle)
Bile acid, documented in cholestasis Ursodeoxycholic acid (Ursodiol) The body's own antioxidant Glutathione Bioregulator peptide Livagen

Simplified: none of these replaces bloodwork, a limited cycle length or avoiding alcohol.

How it works

Part of the problem is absorption. Silymarin is poorly water-soluble and oral bioavailability is correspondingly low. Preparations with a phosphatidylcholine complex or as a silibinin phytosome improve this considerably. Anyone taking plain silymarin should combine it with a meal containing fat, otherwise even less arrives.

That is also a possible explanation for the negative trials: it may be that in several investigations simply too little drug reached the place it was meant to act. That cannot be proven. A hypothesis does not replace a result.

One use is cleanly documented: intravenous silibinin in death cap mushroom poisoning. That is an established emergency application and has little to do with the capsule.

Where it acts

Where silymarin was studied

Tap a point or a card. Grey = observed in studies, no confirmed target in the body is described.

  1. Liver

    Liver values, viral load and survival as on placebo1

    Observed in trials
  2. Stomach and gut

    Gastrointestinal complaints in 12 instead of 5 percent1

    Observed in trials
  3. Skin

    Allergic reactions possible, not with an allergy to the daisy family6

    Observed in trials
Translucent blue glass cells, a ring of blue spheres along the membrane of the central cell, blue molecule chains in between
In the lab silymarin is said to stabilise the membrane of the liver cell. Symbolic image.

Use and dosing

Dosing

Dosing, titration and syringe

Loading the dosing information …

  • Getting started and stepping up, drawn as a staircase
  • Units on the U-100 syringe for every step
  • How long one vial lasts
White folding box with the TPD logo next to a blister of ten round white tablets, two loose tablets in front on a bright lab bench
Tablets in a blister. Symbolic image.

What the research shows

The two methodologically strongest investigations came out negative. SyNCH (JAMA 2012) gave 154 hepatitis C patients high-dose silymarin or placebo over 24 weeks. Two participants in each group reached the primary endpoint. No effect on ALT, viral load or quality of life.

In alcoholic liver cirrhosis (J Hepatol 1998) survival under silymarin and placebo was identical across 200 patients. The Cochrane review (2007) reaches the same conclusion across 18 trials with 1,088 patients: no significant effect on mortality or histology. The apparent effect disappears once only the high-quality trials are considered.

In non-alcoholic steatohepatitis (Clin Gastroenterol Hepatol 2017) the primary endpoint was missed in 99 patients over 48 weeks. A secondary fibrosis finding was positive, but secondary endpoints are signals, not proof.

There is a widely cited positive trial from 1989 showing a survival advantage. It had 170 participants and the p-value sat just under the significance threshold. The effect never reappeared in any of the later, larger and better trials. That is the classic pattern of a chance finding.

Study results

What the trials measured

Interactive: switch tabs, tap points, show or hide arms. Arms are named relative to each other, no dosing advice.

Primary goal after 24 weeks1

Share with normal or halved liver value ALT, 154 people after failed interferon therapy

Primary goal reached1 2 participants per group
Placebo 3.8%
Lower study dose 4.0%
Highest study dose (700 mg) 3.8%

Both doses were well above the usual one. Viral load and quality of life did not differ from placebo either.

NASH after 48 weeks4

Share in percent, 99 people with a biopsy before and after

Primary goal: activity lowered by 30%4 not significant
Placebo 26.0%
Silymarin 32.7%
Less fibrosis in the biopsy4 secondary goal
Placebo 6.0%
Silymarin 22.4%
Liver stiffness down by 30%4 secondary goal
Placebo 2.3%
Silymarin 24.2%

The highest study dose was given. The primary goal was missed, the fibrosis values are secondary goals. The authors consider a larger trial necessary.

Two trials, two results52

Share in percent per group

Alive after 4 years5 1989, 170 people with cirrhosis, just significant
Placebo 39.0%
Silymarin 58.0%
Died during the trial2 1998, 200 alcohol-dependent patients, survival the same
Placebo 14.4%
Silymarin 14.6%

The benefit of the smaller 1989 trial did not reappear in the later, larger trial. The 1998 values are calculated from 14 of 97 and 15 of 103 deaths.

Flowering milk thistle with a purple flower in a beaker of water, next to it a glass liver model on a white table
The best trials came out negative. Symbolic image.

Research status

Where the research stands

On ClinicalTrials.gov 99 trials list silymarin among their interventions. Shown are the trials from this entry and the one on death cap poisoning. The two cirrhosis trials from 1989 and 1998 are not listed there. As of 26 Oct 2026. 7

  1. Preclinical Lab: antioxidant, anti-inflammatory and antifibrotic effects
  2. Phase 1 no registered trial
  3. Phase 2 4 trials, 3 completed, 1 stopped early
  4. Phase 3 no registered trial
  5. Approval in the EU only from long use, not from trials
No proof of efficacy: the EMA classifies milk thistle preparations only as traditional herbal medicines, based on long use and not on trials.6
Show all 4 phase 2 trials on a timelineHide timeline 3 completed 0 running 1 stopped early 2 with results
Phase 2

Bar: start to primary endpoint (planned for running trials). Green = completed, blue = progress until 26 Oct 2026, grey = stopped early.

Side effects

  • Very good tolerability: across all trials the side effect profile sat at placebo level. That is the strongest point of this substance.
  • Mild digestive complaints: occasional, usually temporary.
  • Allergic reactions: rare, possible with an allergy to the daisy family.
  • The real risk: lulling yourself into false security. Silymarin does not replace cycle limits or bloodwork.

Tolerability

Frequency in SyNCH

Out of 100 participants per group, how many had the event over 24 weeks.

5 of 100 Placebo
12 of 100 Silymarin (both doses)
Event PlaceboSilymarin (both doses)
Gastrointestinal complaints1 5%12%
At least one side effect1 40%33%
Serious event1 2%7%

Gastrointestinal values from the results text, the other two calculated from Table 3 of the full text (52 on placebo, 102 on silymarin). No difference was significant. The Cochrane review found no increased risk of side effects.13

Storage

Store dry, at room temperature and protected from light. Keep out of reach of children.

Three white tablet bottles on a bright shelf next to a folded light blue towel
Dry, at room temperature and away from light. Symbolic image.

Related

Related compounds

A different path: all in the TPD lexicon.

Silymarin (milk thistle)
Ursodeoxycholic acid (Ursodiol) Bile acid, also named as liver support Glutathione The body's own antioxidant Livagen Peptide aimed at the liver Anavar (Oxandrolone) 17-alkylated oral, strains the liver Winstrol (Stanozolol) 17-alkylated oral, strains the liver

FAQ

Common questions about Silymarin (milk thistle)

Short answers, each backed by the sources below.

Is silymarin an approved medicine?

Not in the sense of proven efficacy. The EMA classifies milk thistle preparations as traditional herbal medicines: for digestive complaints and to support liver function, after serious conditions have been ruled out by a doctor. The basis is long use, according to the EMA the trials are not enough for firm conclusions.6

What did the SyNCH trial show?

154 people with hepatitis C in whom interferon had not worked received placebo or one of two doses well above the usual one for 24 weeks. Only two participants per group reached the goal. Liver value ALT, viral load and quality of life did not differ.1

Does it help in liver cirrhosis?

That is not proven. A 1989 trial with 170 people found 58 instead of 39 percent alive after 4 years, just significant. A later trial with 200 alcohol-dependent patients found no difference. The Cochrane review of 18 trials saw no effect on mortality.523

And in fatty liver with inflammation (NASH)?

In a trial of 99 people over 48 weeks 32.7 percent reached the primary goal, on placebo 26.0 percent, no significant difference. Among the secondary goals the biopsy more often showed less fibrosis (22.4 versus 6.0 percent). Secondary goals are signals, not proof, the authors call for a larger trial.4

How well is silymarin tolerated?

Well. In SyNCH no more participants had side effects on silymarin than on placebo, gastrointestinal complaints occurred in 12 instead of 5 percent. The Cochrane review found no increased risk. According to the EMA mild gastrointestinal complaints, headache and allergic reactions are described.136

Who should not use it?

According to the EMA not with an allergy to milk thistle or other plants of the daisy family. The traditional preparations are only meant for adults. If complaints last longer than two weeks or get worse, a doctor should look at them.6

What about intravenous silibinin?

Silibinin is the main component of silymarin. Given into the vein it is used in death cap mushroom poisoning, the registry lists a trial with 148 participants that was stopped early. That is emergency treatment in hospital and has little to do with the capsule.7

Glossary

Terms explained briefly

Dotted words in the text open these explanations directly.

ALT
Alanine aminotransferase, a liver value in the blood. It rises when liver cells are damaged.
Bioavailability
Share of a substance that actually reaches the blood after intake.
Cirrhosis
Advanced remodelling of the liver with scar tissue, the liver then works only to a limited extent.
Cochrane review
Systematic analysis of all suitable trials on a question according to fixed rules.
Daisy family
Plant family that includes milk thistle, chamomile and arnica. Anyone reacting to one often reacts to others too.
Fibrosis
Scarring of tissue. In the liver a precursor of cirrhosis.
Flavonolignans
Plant compounds from milk thistle. Silymarin is a mixture of six of them.
NASH
Fatty liver with inflammation not caused by alcohol. It can lead to fibrosis and cirrhosis.
Placebo
Dummy preparation without active substance. Comparing against it shows what is due to the substance itself.
Primary endpoint
The main goal a trial sets in advance. Only this decides whether it succeeded.
Silibinin
The main component of silymarin, also called silybin.

Evidence

Sources

Show all 7 sourcesHide sources 5 Studies1 Trial registry1 Database checked 26 Oct 2026

Studies

  1. SyNCH: silymarin in hepatitis C after failed interferon therapy

    Fried et al., JAMA, 2012

    DOI 10.1001/jama.2012.8265 PMID 22797645 NCT00680342
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed, PMC (Volltext)
  2. Silymarin in alcoholic liver cirrhosis

    Parés et al., Journal of Hepatology, 1998

    DOI 10.1016/S0168-8278(98)80285-7 PMID 9566830
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  3. Cochrane review: milk thistle in alcoholic and viral liver disease

    Rambaldi et al., Cochrane Database of Systematic Reviews, 2007

    DOI 10.1002/14651858.CD003620.pub3 PMID 17943794
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  4. Silymarin in fatty liver with inflammation (NASH)

    Wah Kheong et al., Clinical Gastroenterology and Hepatology, 2017

    DOI 10.1016/j.cgh.2017.04.016 PMID 28419855 NCT02006498
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed
  5. Silymarin in liver cirrhosis, 4-year survival

    Ferenci et al., Journal of Hepatology, 1989

    DOI 10.1016/0168-8278(89)90083-4 PMID 2671116
    Checked 26 Oct 2026 via doi.org, Crossref, PubMed

Trial registry

  1. Trials on silymarin on ClinicalTrials.gov

    ClinicalTrials.gov, U.S. National Library of Medicine

    Checked 26 Oct 2026 via ClinicalTrials.gov API v2

Database

  1. EMA summary on milk thistle fruit (traditional use)

    European Medicines Agency, Ausschuss für pflanzliche Arzneimittel (HMPC)

    Checked 26 Oct 2026 via EMA