What is silybin (silibinin)?

Silybin, also called silibinin, is the main bioactive flavonolignan in milk thistle (silymarin). It is commonly used for liver support and antioxidant effects.

What are the main benefits of silybin?

Silybin is best known for supporting liver cell protection and antioxidant defenses. It may also have anti-inflammatory effects, with emerging research as an adjunct in some clinical settings.

What is a typical silybin dosage?

Common supplemental dosing is about 200–400 mg per day, depending on the product and formulation. Follow the label and consider medical guidance for liver conditions.

Why is silybin bioavailability mentioned so often?

Standard oral silybin can be absorbed poorly, which may limit effects. Some products use enhanced-delivery forms to improve absorption.

Are there safety concerns or interactions with silybin?

Silybin is generally well tolerated but can cause mild gastrointestinal upset in some people. If you take prescription medicines or have liver disease, consult a clinician due to potential drug interaction and monitoring needs.

313 science-backed nutrients

3262 sources considered

Evidence-graded information

Explore by goal or category

Silybin

Moderate study situation·7/10

A higher score indicates better study conditions, but not necessarily effectiveness.

Primary active component of milk thistle silymarin, silybin is a flavonolignan best known for liver protection and antioxidant effects.

Anti-inflammatory Cancer-inhibitor Antioxidant Liver Health

dose range

200–400 mg

Divided 2–3 doses with meals.

Consumption

Take with food; phytosome (with phosphatidylcholine) preparations may improve absorption.

Fat-soluble: take with fat.

Best time

Best taken with the first or second meal of the day.

Description

Silybin (silibinin) is the major bioactive compound in silymarin, the extract of milk thistle seeds. It is widely used for liver health, antioxidant support, and as an adjunct in certain clinical situations, though limited by its oral bioavailability.

benefits

Main effects with level of evidence

Moderate

Note on evidence

Clinical studies support benefits for liver health, while most anti-inflammatory and anti-cancer findings are preliminary or preclinical.

Protects and supports liver health

Moderate

Silybin supports liver cell membrane stability, enhances regeneration, and protects the liver from toxins, alcohol, and certain drugs. It is used adjunctively in chronic liver diseases and may improve markers such as ALT, AST, and histological outcomes.

Particularly relevant for: Liver Health

2 · PubMed - Silymarin in Liver Diseases: What is the Clinical Evidence?5 · NIH LiverTox: Clinical and Research Information on Drug-Induced Liver Injury 6 · Examine.com - Milk Thistle (Silymarin)7 · National Center for Complementary and Integrative Health - Milk Thistle

Antioxidant activity

Moderate

Acts as a free radical scavenger and supports cellular antioxidant defense, reducing markers of oxidative stress, particularly in metabolic conditions.

Particularly relevant for: Antioxidant

3 · PubMed - Effects of Silybin-Phosphatidylcholine Complex on Oxidative Stress in Type 2 Diabetics 6 · Examine.com - Milk Thistle (Silymarin)

Anti-inflammatory effects

Limited

Preclinical and some clinical evidence suggests silybin may lower inflammation by inhibiting pro-inflammatory cytokines, potentially benefiting metabolic and inflammatory diseases.

Particularly relevant for: Anti-inflammatory

6 · Examine.com - Milk Thistle (Silymarin)7 · National Center for Complementary and Integrative Health - Milk Thistle

Emerging anti-cancer adjunct

Limited

Preclinical and limited clinical studies indicate potential in inhibiting tumor cell growth and enhancing effects of conventional cancer therapies.

Particularly relevant for: Cancer-inhibitor

4 · PubMed - Silybin and Cancer Chemoprevention: Insight from Bench to Bedside 6 · Examine.com - Milk Thistle (Silymarin)

Safety & Information

Important safety information & known risks

For educational purposes only • not medical advice

Generally well tolerated; main concerns are allergy, drug interactions, and use in special populations.

warning notices

Allergic reactions, including rash or difficulty breathing, can occur, especially in individuals hypersensitive to Asteraceae family plants.
Gastrointestinal upset, headache, and mild allergic symptoms are rare but possible.
Major drug interactions are uncommon but theoretically possible via hepatic enzyme modulation.
Avoid if allergic to Asteraceae/Compositae (daisy) family plants.
Use caution and consult a healthcare provider when taking anticoagulant or antidiabetic medications due to potential drug interactions.
Not recommended during pregnancy or breastfeeding due to limited safety data.
Monitor for signs of allergic reaction such as rash or difficulty breathing.

Known interactions with medications

Anticoagulants
Antidiabetic medications

Contraindications / special precautions

Allergy to milk thistle or other Asteraceae family plants
Pregnancy and breastfeeding (due to limited data)

interactions

Important interactions between active ingredient ↔ supplement / medication / food

Silybin may affect drug metabolism and glycemic control; also, its effects can be influenced by other flavonoids or supplements.

May potentiate effects of anticoagulant drugs.

drug · Anticoagulants

CautionLimited

Why

Silybin may affect cytochrome P450 enzymes involved in drug metabolism, potentially increasing anticoagulant activity.

recommendation

Use cautiously and monitor for increased bleeding risk.

1 · WebMD - Milk Thistle 6 · Examine.com - Milk Thistle (Silymarin)

May enhance hypoglycemic effect of antidiabetic drugs.

drug · Antidiabetic drugs

CautionLimited

Why

Silybin may reduce blood glucose and alter metabolism of diabetes medications.

recommendation

Monitor blood glucose closely if taken with antidiabetic agents.

1 · WebMD - Milk Thistle 6 · Examine.com - Milk Thistle (Silymarin)

mechanisms of action

Brief explanations of how it works

Antioxidant enzyme modulation

Silybin increases activity of antioxidant enzymes such as superoxide dismutase and glutathione peroxidase, helping to reduce oxidative stress in cells.

3 · PubMed - Effects of Silybin-Phosphatidylcholine Complex on Oxidative Stress in Type 2 Diabetics