Plant Profile

Milk Thistle

Compiled by the Omnia Sana editorial team from the plant database ·Last updated August 15, 2026

Silybum marianum

Family: Asteraceae · Parts used: Seed (fruit) · Also known as: Mary thistle, Holy thistle, Silybum

The complete database record: 2 documented constituents, 6 pharmacological actions, 7 traditional / indicated uses, with 18 cited sources.

Botanical Description

Robust biennial (occasionally annual) thistle (Asteraceae), 30-150 cm tall. Leaves are glossy dark green with distinctive white marbled veining (the 'milk' of legend), spiny-margined and deeply lobed. Large, solitary, purple-pink thistle-type flower heads are surrounded by spiny bracts, followed by shiny, mottled brown-black seeds - the part used.^[12]

Height: 30-150 cm

Habit: Robust biennial (occasionally annual) thistle

Leaves: Glossy dark green with white marbled veining, spiny-margined, deeply lobed

Flowers: Large, solitary, purple-pink thistle heads with spiny bracts

Stem: Erect, ridged

Root: Deep taproot

Fruit: Shiny, mottled brown-black seed (achene)

Flowering Period: June-August

Habitat & Distribution

Native to the Mediterranean region, now naturalised worldwide on disturbed, sunny ground - roadsides, waste places and dry pastures - and widely cultivated commercially for its seed.^[12]

Harvesting

Seed heads are harvested once fully dry (late summer), and the seeds (fruit) are threshed out.^[12]

Parts: Seed (fruit)

Season: Late summer

Key Constituents

Silymarin (a flavonolignan complex)^{[12, 13]}

The active complex; silybin (silibinin) is the most active component, with silydianin and silychristin.

Silymarin (silybin)

Flavonoids^[13]

Additional antioxidant constituents of the seed.

Flavonoids

Pharmacological Actions

Anti-inflammatory^{[11, 12, 13]}

Anti-inflammatory and antioxidant

Anticancer (preclinical)^{[5, 13]}

Antidiabetic (blood-sugar lowering)^{[10, 15]}

Improves glycemic control in type 2 diabetes - lowers fasting blood glucose and HbA1c

Antioxidant^{[2, 6, 12, 13]}

Anti-inflammatory and antioxidant; Hepatoprotective / liver support (protects liver cells, antioxidant and antifibrotic)

Digestive aid^[12]

Digestive support / mild dyspepsia (traditional)

Hepatoprotective (liver support)^{[1, 2, 3, 4, 6, 7, 9, 12, 13, 16]}

Hepatoprotective / liver support (protects liver cells, antioxidant and antifibrotic); May improve liver enzymes and hepatic fat in non-alcoholic fatty liver disease (NAFLD); Supports liver recovery and 'detox' (traditional framing of the hepatoprotective action)

Traditional & Indicated Uses

Arthritis / joint pain

inferred from anti-inflammatory action

Mechanistic Exclude Ids: REF-0483, REF-0484

Evidence: 1

Label: Arthritis / joint pain

more plants for arthritis / joint pain →detailed sources →

Blood sugar / diabetes support^[15]Good · 7/10

Improves glycemic control in type 2 diabetes - lowers fasting blood glucose and HbA1c

Evidence: 7

Label: Blood sugar / diabetes support

more plants for blood sugar / diabetes support →detailed sources →

Cancer (anticancer research)^{[5, 13]}Good · 7/10

inferred from anticancer action

Evidence: 7

Label: Cancer (anticancer research)

more plants for cancer (anticancer research) →detailed sources →

Detox / cleansing^[12]Moderate · 5/10

Supports liver recovery and 'detox' (traditional framing of the hepatoprotective action)

Evidence: 5

Label: Detox / cleansing

more plants for detox / cleansing →detailed sources →

Inflammation (general)^[13]Preliminary · 2/10

inferred from anti-inflammatory action

Mechanistic Exclude Ids: REF-0483

Evidence: 2

Label: Inflammation (general)

more plants for inflammation (general) →detailed sources →

Liver support^{[12, 13, 16]}Good · 8/10

Hepatoprotective / liver support (protects liver cells, antioxidant and antifibrotic); May improve liver enzymes and hepatic fat in non-alcoholic fatty liver disease (NAFLD)

Evidence: 8

Label: Liver support

more plants for liver support →detailed sources →

Metabolic support^[15]Good · 7/10

inferred from antidiabetic action

Evidence: 7

Label: Metabolic support

more plants for metabolic support →detailed sources →

Traditional Use & History

Milk thistle has a very long European folk-medicine tradition, documented since antiquity, as a liver tonic, and its seed extract, standardised to the flavonolignan complex silymarin, is one of the most extensively studied herbal hepatoprotectants. Modern research supports antioxidant, anti-inflammatory and liver-protective activity, with growing interest in metabolic/blood-sugar effects.^{[12, 13]}

Preparations

Standardised extract (capsule/tablet)^{[12, 13]}

Standardised to silymarin content (typically 70-80%), the clinically studied commercial form.

Dosage

Standardised extract^{[12, 13]}

Clinical trials have most often used standardised extract providing 200-450 mg/day of silymarin, divided into 2-3 doses. Educational reference only, not a prescription.

Safety, Cautions & Contraindications

Safety note^[12]Info

Very well tolerated, even at high doses; the main effects are mild gastrointestinal upset (nausea, loose stools). As a member of the daisy family (Asteraceae), it can cause allergic reactions in sensitive people.

Safety note^[12]Caution

Has a low potential for drug interactions (little effect on liver CYP enzymes), but use caution with medicines that have a narrow therapeutic window. Human pregnancy data are limited, so use cautiously.

Herb-Drug Interactions

Cyp3a4 Substrates^[17]Likely-safe

Mechanism: Milk thistle (silymarin) was once thought to inhibit the CYP3A4 enzyme, but a controlled human study found no meaningful effect on a CYP3A4 test drug, so clinically important interactions with CYP3A4-metabolised medicines are unlikely at usual doses.

Reviewed By: Omnia Sana (owner-authorized)

Reviewed Date: 2026-07-03

Antidiabetics^{[15, 18]}Caution

Mechanism: Milk thistle (silymarin) reduced fasting blood glucose and HbA1c across randomized trials in type 2 diabetes; combined with diabetes medicines it may add to blood-sugar lowering, so monitor blood sugar.

Reviewed By: Omnia Sana (owner-authorized)

Reviewed Date: 2026-07-03

Harvest Readiness

^[14]

Part: seed

Signals: Collect the seed in late summer to autumn, as the flower heads ripen, dry and open to release the pappus-borne seed.

Basis: traditional

Source Quote: the seeds ripen from August to October

Species Confirmed: 1

Notes: PFAF (REF-3337); the seeds ripen in late summer to autumn (August-October), harvested as the heads dry. Single lineage -> provisional.

External Identifiers

GBIF ›Wikidata ›

References & Sources

Abenavoli, L., Izzo, A.A., Milic, N., Cicala, C., Santini, A. and Capasso, R (2018) 'Milk thistle (Silybum marianum): A concise overview on its chemistry, pharmacological, and nutraceutical uses in liver diseases', Phytotherapy Research, 32(11), pp. 2202-2213. doi:10.1002/ptr.6171 Meta-analysis / review
https://doi.org/10.1002/ptr.6171
Bahmani, M., Shirzad, H., Rafieian, S. and Rafieian-Kopaei, M (2015) 'Silybum marianum: Beyond Hepatoprotection', Journal of Evidence-Based Complementary & Alternative Medicine, 20(4), pp. 292-301. doi:10.1177/2156587215571116 Meta-analysis / review
https://doi.org/10.1177/2156587215571116
Wang, X., Zhang, Z. and Wu, S (2020) 'Health Benefits of Silybum marianum: Phytochemistry, Pharmacology, and Applications', Journal of Agricultural and Food Chemistry, 68(42), pp. 11644-11664. doi:10.1021/acs.jafc.0c04791 Meta-analysis / review
https://doi.org/10.1021/acs.jafc.0c04791
Marmouzi, I., Bouyahya, A., Ezzat, S.M., El Jemli, M. and Kharbach, M (2020) 'The food plant Silybum marianum (L.) Gaertn.: Phytochemistry, Ethnopharmacology and clinical evidence', Journal of Ethnopharmacology, 265, pp. 113303. doi:10.1016/j.jep.2020.113303 Meta-analysis / review
https://doi.org/10.1016/j.jep.2020.113303
Greenlee, H., Abascal, K., Yarnell, E. and Ladas, E (2007) 'Clinical applications of Silybum marianum in oncology', Integrative Cancer Therapies, 6(2), pp. 158-165. doi:10.1177/1534735407301727 Meta-analysis / review
https://doi.org/10.1177/1534735407301727
Shaker, E., Mahmoud, H. and Mnaa, S (2009) 'Silymarin, the antioxidant component and Silybum marianum extracts prevent liver damage', Food and Chemical Toxicology, 48(3), pp. 803-806. doi:10.1016/j.fct.2009.12.011 Preclinical
https://doi.org/10.1016/j.fct.2009.12.011
Flora, K., Hahn, M., Rosen, H. and Benner, K (1998) 'Milk thistle (Silybum marianum) for the therapy of liver disease', American Journal of Gastroenterology, 93(2), pp. 139-143. doi:10.1111/j.1572-0241.1998.00139.x Meta-analysis / review
https://doi.org/10.1111/j.1572-0241.1998.00139.x
Csupor, D., Csorba, A. and Hohmann, J (2016) 'Recent advances in the analysis of flavonolignans of Silybum marianum', Journal of Pharmaceutical and Biomedical Analysis, 130, pp. 301-317. doi:10.1016/j.jpba.2016.05.034 Meta-analysis / review
https://doi.org/10.1016/j.jpba.2016.05.034
Ball, K.R. and Kowdley, K.V (2005) 'A review of Silybum marianum (milk thistle) as a treatment for alcoholic liver disease', Journal of Clinical Gastroenterology, 39(6), pp. 520-528. doi:10.1097/01.mcg.0000165668.79530.a0 Meta-analysis / review
https://doi.org/10.1097/01.mcg.0000165668.79530.a0
Tajmohammadi, A., Razavi, B.M. and Hosseinzadeh, H (2018) 'Silybum marianum (milk thistle) and its main constituent, silymarin, as a potential therapeutic plant in metabolic syndrome: A review', Phytotherapy Research, 32(10), pp. 1933-1949. doi:10.1002/ptr.6153 Meta-analysis / review
https://doi.org/10.1002/ptr.6153
Ghahfarrokhi, S.H., Heidari-Soureshjani, S., Sherwin, C.M.T. and Azadegan-Dehkordi, Z (2024) 'Efficacy and Mechanisms of Silybum marianum, Silymarin, and Silibinin on Rheumatoid Arthritis and Osteoarthritis Symptoms: A Systematic Review', Current Rheumatology Reviews, 20(4), pp. 414-425. doi:10.2174/0115733971266397231122080247 Meta-analysis / review
https://doi.org/10.2174/0115733971266397231122080247
Soleimani, V., Delghandi, P.S., Moallem, S.A. and Karimi, G (2019) 'Safety and toxicity of silymarin, the major constituent of milk thistle extract: An updated review', Phytotherapy Research. doi:10.1002/ptr.6361 Randomized trial
https://doi.org/10.1002/ptr.6361
Fallah, M., Davoodvandi, A., Nikmanzar, S., Aghili, S., Mirazimi, S.M.A., Aschner, M., Rashidian, A., Hamblin, M.R., Chamanara, M., Naghsh, N. and Mirzaei, H (2021) 'Silymarin (milk thistle extract) as a therapeutic agent in gastrointestinal cancer', Biomedicine & Pharmacotherapy. doi:10.1016/j.biopha.2021.112024 Preclinical
https://doi.org/10.1016/j.biopha.2021.112024
Plants For A Future 'Silybum marianum (Milk Thistle)'. Available at: https://pfaf.org/user/Plant.aspx?LatinName=Silybum+marianum Traditional / reference
https://pfaf.org/user/Plant.aspx?LatinName=Silybum+marianum
Voroneanu, L., Nistor, I., Dumea, R., Apetrii, M. and Covic, A (2016) 'Silymarin in Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis of Randomized Controlled Trials', Journal of Diabetes Research. doi:10.1155/2016/5147468 Meta-analysis / review
https://doi.org/10.1155/2016/5147468
Zhou, J., Chen, Y., Yu, J., Li, T., Lu, Z., Chen, Y., Zhang, X. and Ye, F (2021) 'The efficacy of novel metabolic targeted agents and natural plant drugs for nonalcoholic fatty liver disease treatment: A PRISMA-compliant network meta-analysis of randomized controlled trials', Medicine (Baltimore), 100(12). doi:10.1097/MD.0000000000024884 Meta-analysis / review
https://doi.org/10.1097/MD.0000000000024884
Fuhr, U., Beckmann-Knopp, S., Jetter, A., Lueck, H. and Mengs, U (2007) 'The effect of silymarin on oral nifedipine pharmacokinetics', Planta Medica, 73(14), pp. 1429-1435. doi:10.1055/s-2007-990256 Randomized trial
https://doi.org/10.1055/s-2007-990256
Hadi, A., Pourmasoumi, M., Mohammadi, H., Symonds, M. and Miraghajani, M (2018) 'The effects of silymarin supplementation on metabolic status and oxidative stress in patients with type 2 diabetes mellitus: A systematic review and meta-analysis of clinical trials', Complementary Therapies in Medicine, 41, pp. 311-319. doi:10.1016/j.ctim.2018.08.010 Meta-analysis / review
https://doi.org/10.1016/j.ctim.2018.08.010

Selected studies & references

ReviewEfficacy and Mechanisms of Silybum marianum, Silymarin, and Silibinin on Rheumatoid Arthritis and Osteoarthritis Symptoms: A Systematic Review source↗ (2024)

ReviewThe efficacy of novel metabolic targeted agents and natural plant drugs for nonalcoholic fatty liver disease treatment: A PRISMA-compliant network meta-analysis of randomized controlled trials source↗ (2021)

ReviewHealth Benefits of Silybum marianum: Phytochemistry, Pharmacology, and Applications source↗ (2020)

ReviewThe food plant Silybum marianum (L.) Gaertn.: Phytochemistry, Ethnopharmacology and clinical evidence source↗ (2020)

ReviewMilk thistle (Silybum marianum): A concise overview on its chemistry, pharmacological, and nutraceutical uses in liver diseases source↗ (2018)

ReviewSilybum marianum (milk thistle) and its main constituent, silymarin, as a potential therapeutic plant in metabolic syndrome: A review source↗ (2018)

ReviewThe effects of silymarin supplementation on metabolic status and oxidative stress in patients with type 2 diabetes mellitus: A systematic review and meta-analysis of clinical trials source↗ (2018)

ReviewRecent advances in the analysis of flavonolignans of Silybum marianum source↗ (2016)

All 17 studies in the Knowledge Finder →

Educational use only. This profile summarises traditional and scientific sources for reference. It is not medical advice and not a substitute for a qualified practitioner. Some plants carry safety cautions and drug interactions - always check before use.
This profile is assembled automatically from the Omnia Sana plant database, which we curate by hand. How this site is built.

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