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milk thistle

© 2018 Steven Foster

A milk thistle monograph for the home

Latin Name: Silybum marianum

Common Names: milk thistle, Mary thistle, holy thistle.

This milk thistle monograph provides basic information about milk thistle—common names, usefulness and safety, and resources for more information.


Milk Thistle Basics

  • Milk thistle is native to southern Europe, southern Russia, Asia Minor, and northern Africa. It also grows in North and South America and South Australia.
  • Silymarin is considered to be the main component of milk thistle seeds, but the terms “milk thistle” and “silymarin” often are used interchangeably.
  • Historically, people have used milk thistle for liver disorders, such as hepatitis and cirrhosis, and gallbladder problems.
  • Silymarin is the most commonly used herbal supplement in the United States for liver problems.
  • Milk thistle products are available as capsules, powders, and extracts.

Milk Thistle in Health Research

  • We know little about whether milk thistle is effective in people, as only a few well-designed clinical studies have been conducted.

Milk Thistle Research Summary

  • Results from clinical trials of milk thistle for liver diseases have been mixed, and two rigorously designed studies found no benefit.
  • The 2008 Hepatitis C Antiviral Long-Term Treatment Against Cirrhosis (HALT-C) study, sponsored by the National Institutes of Health (NIH), found that hepatitis C patients who used silymarin had fewer and milder symptoms of liver disease and somewhat better quality of life but no change in virus activity or liver inflammation.
  • A 2012 clinical trial, cofunded by the National Center for Complementary and Integrative Health (NCCIH) and the National Institute of Diabetes and Digestive and Kidney Diseases, showed that two higher-than-usual doses of silymarin were no better than placebo for chronic hepatitis C in people who had not responded to standard antiviral treatment.
  • Results from a 2013 clinical study suggest that milk thistle may enhance standard treatment in young people with a particular form of anemia (Cooley’s anemia).

Milk Thistle Safety

  • In clinical trials, milk thistle appears to be well tolerated in recommended doses. Occasionally, people report various gastrointestinal side effects.
  • Milk thistle may produce allergic reactions, which tend to be more common among people who are allergic to plants in the same family (for example, ragweed, chrysanthemum, marigold, and daisy).
  • Compounds in milk thistle may lower blood sugar levels in people with type 2 diabetes. People with diabetes should use caution.

Milk Thistle References


PubMed Articles About Silybum marianum

Source: National Center for Biotechnology Information (NCBI)[Internet]. Bethesda (MD): National Library of Medicine (US), National Center for Biotechnology Information; [1988] – [cited 2018 Apr 5]. Available from:

Saberi, Z., Gorji, N., Memariani, Z., Moeini, R., Shirafkan, H., Amiri, M., (2021) Evaluation of the effect of Silybum marianum extract on menopausal symptoms: A randomized, double-blind placebo-controlled trial.

The tendency to use herbs to manage menopausal symptoms has increased in recent years. The purpose of this study was to evaluate the effect of Silybum marianum (L.) compared with placebo in women with hot flashes. Eighty women were randomly allocated into two equal groups (S. marianum extract [400 mg/d] or placebo capsules). Hot flashes frequency and severity were evaluated in 12 weeks with the Greene Climacteric Scale (GCS) and the Hot Flash Related Daily Interference Scale (HFRDIS). The data were analyzed in SPSS software using t-test, Mann-Whitney, chi-square test and repeated measure analysis. Hot flashes frequency and severity decreased from 4.32 ± 0.20/day to 1.31 ± 0.15/day and from 5.25 ± 0.22 to 1.62 ± 0.08, respectively, during the study in test group (p < .001) which were significantly better than effects of placebo in all steps of study (p < .001). Significant decreases in GCS and HFRDIS scores were also detected in S. marianum group compared with placebo after 4, 8 and 12 weeks (p < .001). The results showed that S. marianum can decrease frequency and severity of hot flashes significantly. Considering the safety and high consumption of this herbal medicine worldwide, its use in women with menopausal symptoms can be helpful.

Shi, Z., Wu, J., Yang, Q., Xia, H., Deng, M., Yang, Y., (2021) Efficacy and safety of milk thistle preventive treatment of anti-tuberculosis drug-induced liver injury: A protocol for systematic review and meta-analysis.

Tuberculosis is an infectious disease caused by mycobacterium tuberculosis. It may occur in multiple parts and organs of the patients body, and the lung is the most common. It is a major health threat worldwide. Hepatotoxicity is a common adverse reaction of commonly used clinical anti-tuberculosis drugs, as well as one of the important factors leading to poor prognosis of tuberculosis. Milk thistle is a traditional Chinese medicine extract derived from the mature fruit of Silybum marianum. Clinical practice shows that milk thistle has a good anti-liver injury effect and can be used to prevent anti-tuberculosis drug-induced liver injury. However, there is a lack of evidence-based medicine. The research carried out in this protocol is to systematically evaluate the efficacy and safety of milk thistle preventive treatment of anti-tuberculosis drug-induced liver injury, and to improve the evidence-based basis for clinical application of milk thistle in the preventive treatment of anti-tuberculosis drug-induced liver injury.

Tóth, B., Németh, D., Soós, A., Hegyi, P., Pham-Dobor, G., Varga, O., Varga, V., Kiss, T., Sarlós, P., Erőss, B., Csupor, D., (2020) The Effects of a Fixed Combination of Berberis aristata and Silybum marianum on Dyslipidaemia - A Meta-analysis and Systematic Review.

A fixed combination of and (Berberol) has been used by patients with dyslipidaemia. The aim of the present meta-analysis was to systematically evaluate the efficacy and safety of a fixed combination of and (Berberol) on serum lipid levels compared to placebo in a meta-analysis based on randomised, controlled trials. The meta-analysis was reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement, using the PICO (patients, intervention, comparison, outcome) format, and it was registered in the International Prospective Register of Systematic Reviews. The Cochrane Central Register of Controlled Trials, PubMed, Embase, and Web of Science databases were searched for relevant studies. Placebo-controlled clinical studies involving adult patients with a condition of dyslipidaemia and receiving a fixed combination of and were included. Four randomised trials, including a total of 491 patients, were pooled in statistical analysis. According to the present meta-analysis, Berberol significantly lowered the low-density lipoprotein level, total cholesterol, fasting plasma glucose levels, and the Homeostatic Model Assessment index compared to placebo; however, its effects on the high-density lipoprotein level, triglyceride level, and body mass index were not statistically significant by the end of a 3-month treatment period. Berberol appeared to be safe, and it did not increase the levels of alanine transaminase, aspartate transaminase, and creatine kinase enzymes. Berberol is an effective and presumably safe complementary therapy for the treatment of dyslipidaemia; however, the evidence supporting its use is very limited. The optimum dose and duration of treatment are unclear. A comprehensive evaluation of efficacy and safety is required in further high-quality clinical studies involving larger patient populations.

Grant, JE., Redden, SA., Chamberlain, SR., (2020) Milk Thistle Treatment for Children and Adults with Trichotillomania: A Double-Blind, Placebo-Controlled, Crossover Negative Study.

Data on the pharmacological treatment of trichotillomania are limited. Milk thistle has antioxidant properties and showed promise in trichotillomania in a prior case report. The goal of the current study was to determine the efficacy and tolerability of silymarin in children and adults with trichotillomania.

Jowkar, F., Godarzi, H., Parvizi, MM., (2020) Can we consider silymarin as a treatment option for vitiligo? A double-blind controlled randomized clinical trial of phototherapy plus oral product versus phototherapy alone.

Vitiligo is a chronic skin disorder caused by destruction of the skin melanocytes, which presents as a depigmented area in the skin. This study examined the effect of Phototherapy plus oral on the treatment of skin lesions of Vitiligo. In this randomized controlled clinical trial, 34 patients with vitiligo who were referred to Dermatology Clinic of Shahid Faghihi Hospital, Shiraz, Iran, were randomly divided into two groups. The first group was treated with phototherapy plus Narrowband UVB plus oral silymarin and the other group was treated with phototherapy with placebo. The patients in both groups were evaluated with vitiligo area severity index (VASI) at the beginning and end of the study. SPSS software version 23 was used for statistical analyses. The mean of the VASI score showed a statistically significant decrease in both groups at the end of the study ( < .05), but the decrease in the VASI score in patients who received was more in comparison with the other group. This study showed that probably is a good choice for patients with vitiligo; however, further studies are recommended to be conducted to confirm our result.