- Bull thistle, cardo blanco, Cardui mariae fructus, Cardui mariae herba, Cardum marianum L., Carduus marianus L., Chardon-Marie, emetic root, flavonolignans, Frauendistel, Fructus Silybi mariae, fruit de chardon Marie, heal thistle, holy thistle, isosilibinin, isosilybin, kanger, kocakavkas, kuub, lady’s thistle, Legalon®, Marian thistle, mariana mariana, Mariendistel, Marienkrörner, Mary thistle, mild thistle, milk ipecac, natursil, natursilum, Our Lady’s thistle, pig leaves, royal thistle, shui fei ji, silidianin, Silybi mariae fructus, silybin, silybinin, Silybum marianum, silychristin, silymarin, snake milk, sow thistle, St. Mary’s thistle, thisylin, Venus thistle, variegated thistle, wild artichoke.
- Milk thistle has been used medicinally for over 2,000 years, most commonly for the treatment of liver and gallbladder disorders. A flavonoid complex called silymarin can be extracted from the seeds of milk thistle and is believed to be the biologically active component. The terms “milk thistle” and “silymarin” are often used interchangeably.
- Milk thistle products are popular in Europe and the United States for various types of liver disease. Although numerous human trials have been published, most studies have not been well designed or reported.
These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.
Multiple studies from Europe suggest benefits of oral milk thistle for cirrhosis. In experiments up to five years long, milk thistle has improved liver function and decreased the number of deaths that occur in cirrhotic patients. Although these results are promising, most studies have been poorly designed. Better research is necessary before a strong recommendation can be made.
Several studies of oral milk thistle for hepatitis caused by viruses or alcohol report improvements in liver tests. However, most studies have been small and poorly designed. More research is needed before a strong recommendation can be made.
Research on milk thistle for acute viral hepatitis has not provided clear results, and milk thistle cannot be recommended for this potentially life-threatening condition.
Milk thistle has been used traditionally to treat Amanita phalloides mushroom poisoning. However, there are not enough reliable studies in humans to support this use of milk thistle.
There are early reports from laboratory experiments that the chemicals silymarin and silibinin in milk thistle reduce the growth of human breast, cervical, and prostate cancer cells. There is also one report of a patient with liver cancer who improved following treatment with milk thistle. However, this research is too early to draw a firm conclusion, and effects have not been shown in high-quality human trials.
A small number of studies suggest possible improvements of blood sugar control in cirrhotic patients with diabetes. However, there is not enough scientific evidence to recommend milk thistle for this use.
An herbal preparation containing milk thistle may be effective in decreasing symptoms of functional dyspepsia. However, milk thistle alone has not been researched.
Although animal and laboratory research suggests cholesterol-lowering effects of milk thistle, human studies have provided unclear results. Further studies are necessary before a firm recommendation can be made.
Several studies suggest possible benefits of milk thistle to treat or prevent liver damage caused by drugs or toxic chemicals. Results of this research are not clear, and most studies have been poorly designed. Therefore, there is not enough scientific evidence to recommend milk thistle for this use.
An herbal preparation containing milk thistle may be effective in decreasing menopausal symptoms. However, milk thistle alone has not been researched.
*Key to grades:
The below uses are based on tradition, scientific theories, or limited research. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. There may be other proposed uses that are not listed below.
Adults (over 18 years old)
- Silymarin (Legalon®) 230-600 milligrams per day divided into two to three doses has been studied.
- Silipide® (IdB 1016) 160-480 milligrams per day in silybin equivalents has also been studied.
Children (under 18 years old)
- There is not enough scientific data to recommend milk thistle for use in children.
The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.
- People with allergies to plants in the aster family (Compositae, Asteraceae) or to daisies, artichokes, common thistle, kiwi, or to any of milk thistle’s constituents (silibinin, silychistin, silydianin, silymonin, siliandrin) may have allergic reactions to milk thistle. Anaphylactic shock (a severe allergic reaction) from milk thistle tea or tablets has been reported in several patients. Overall, silymarin has a good safety record with rare case reports of gastrointestinal disturbances and allergic skin rashes published.
Side Effects and Warnings
- Milk thistle appears to be well tolerated in recommended doses for up to six years. Some patients in studies have experienced stomach upset, headache, and itching. There are rare reports of appetite loss, gas, heartburn, diarrhea, joint pain, and impotence with milk thistle use. One person experienced sweating, nausea, stomach pain, diarrhea, vomiting, weakness, and collapse after taking milk thistle. This reaction may have been due to an allergic reaction, and improved after 24 hours. High liver enzyme levels in one person taking milk thistle returned to normal after the person stopped taking the herb.
- In theory, milk thistle may lower blood sugar levels. Caution is advised in patients with diabetes or hypoglycemia, and in those taking drugs, herbs, or supplements that affect blood sugars. Serum glucose levels may need to be monitored by a healthcare provider, and medication adjustments may be necessary.
- Theoretically, because milk thistle plant extract might have estrogenic effects, women with hormone sensitive conditions should avoid milk thistle above ground parts. Some of these conditions include breast, uterine, and ovarian cancer, endometriosis, and uterine fibroids. The more commonly used milk thistle seed extracts are not known to have estrogenic effects.
- Exacerbation of hemochromatosis has been associated with ingestion of milk thistle.
Pregnancy and Breastfeeding
- Milk thistle has been used historically to improve breast milk flow, and two brief studies of milk thistle in pregnant women reported no side effects. However, there is not enough scientific evidence to support the safe use of milk thistle during pregnancy or breastfeeding at this time.
The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.
Interactions with Drugs
- Animal studies suggest that milk thistle may interfere with the way the body processes certain drugs using the liver’s “cytochrome P450” enzyme system. As a result, the levels of these drugs may be increased in the blood, and may cause increased effects or adverse reactions. Many types of drugs may be affected. Individuals should speak with a qualified healthcare provider to obtain a list of these drugs and their possible interactions. In theory, milk thistle may lower blood sugar levels. Caution is advised when using medications that may also lower blood sugar. Patients taking drugs for diabetes by mouth or insulin should be monitored closely by a qualified healthcare provider. Medication adjustments may be necessary.
- A possible interaction with phenytoin (Dilantin®) has been reported with milk thistle. However, the facts are unclear.
- Milk thistle ingredients have been reported to prevent amiodarone toxicity in animal studies. Based on laboratory and animal study, milk thistle may increase the effects of chemotherapy drugs like doxorubicin, cisplatin, and carboplatin. Milk thistle may interact with hormonal agents, alcohol, or antiretroviral drugs.
Interactions with Herbs and Dietary Supplements
- Animal studies suggest that milk thistle may interfere with the way the body processes certain herbs or supplements using the liver’s “cytochrome P450” enzyme system. As a result, the levels of other herbs or supplements may be too high in the blood. It may also alter the effects that other herbs or supplements have on the P450 system.
- Milk thistle may lower blood sugar levels. Caution is advised when using herbs or supplements that may also lower blood sugar. Blood glucose levels may require monitoring, and doses may need adjustment.
- Milk thistle may also interact with herbs and supplements with hormonal, antiretroviral or antioxidant effects. Milk thistle may interfere with iron absorption and slow calcium metabolism.
Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy.
- This information is based on a systematic review of scientific literature edited and peer-reviewed by contributors to the Natural Standard Research Collaboration ().
- Ladas EJ, Kelly KM. Milk thistle: is there a role for its use as an adjunct therapy in patients with cancer? J Altern Complement Med 2003;9(3):411-416.
- Lawrence V, Jacobs B, Dennehy C, et al. Report on milk thistle: effects on liver disease and cirrhosis and clinical adverse effects. Evidence Report/Technology Assessment No. 21 (Contract 290-97-0012 to the San Antonio Evidence-based Practice Center, based at the University of Texas Health Science Center at San Antonio, and The Veterans Evidence-based Research, Dissemination, and Implementation Center, a Veterans Affairs Services Research and Development Center of Excellence). AHRQ Publication No. 01-E025. Rockville, MD: Agency for Healthcare Research and Quality. October 2000.
- Lucena MI, Andrade RJ, de la Cruz JP, et al. Effects of silymarin MZ-80 on oxidative stress in patients with alcoholic cirrhosis. Results of a randomized, double-blind, placebo-controlled clinical study. Int J Clin Pharmacol Ther 2002;40(1):2-8.
- Madisch A, Melderis H, Mayr G, et al. [A plant extract and its modified preparation in functional dyspepsia. Results of a double-blind placebo controlled comparative study]. Z Gastroenterol 2001;39(7):511-517.
- McCord A. Milk thistle may help improve liver health in people with HIV and hepatitis C. Proj Inf Perspect. 2008 Sep;(46):18.
- Melhem A, Stern M, Shibolet O, et al. Treatment of chronic hepatitis C virus infection via antioxidants: results of a phase I clinical trial. J Clin Gastroenterol 2005 Sep;39(8):737-42.
- Pares A, Planas R, Torres M, et al. Effects of silymarin in alcoholic patients with cirrhosis of the liver: results of a controlled, double-blind, randomized and multicenter trial. J Hepatol 1998;28(4):615-621.
- Rambaldi A, Jacobs BP, Iaquinto G, et al. Milk thistle for alcoholic and/or hepatitis B or C liver diseases–a systematic cochrane hepato-biliary group review with meta-analyses of randomized clinical trials. Am J Gastroenterol 2005 Nov;100(11):2583-91.
- Rambaldi A, Jacobs BP, Gluud C. Milk thistle for alcoholic and/or hepatitis B or C virus liver diseases. Cochrane Database Syst Rev. 2007 Oct 17;(4):CD003620. Update of Cochrane Database Syst Rev 2005;(2):CD003620.
- Schroder FH, Roobol MJ, Boeve ER, et al. Randomized, double-blind, placebo-controlled crossover study in men with prostate cancer and rising PSA: effectiveness of a dietary supplement. Eur Urol 2005 Dec;48(6):922-30; discussion 930-1.
- Tyagi AK, Singh RP, Agarwal C, et al. Silibinin strongly synergizes human prostate carcinoma DU145 cells to doxorubicin-induced growth Inhibition, G2-M arrest, and apoptosis. Clin Cancer Res 2002;8(11):3512-3519.
- Velussi M, Cernigoi AM, Viezzoli L, et al. Silymarin reduces hyperinsulinemia, malondialdehyde levels, and daily insulin need in cirrhotic diabetic patients. Curr Ther Res 1993;53(5):533-545.
- Velussi M, Cernigoi AM, De Monte A, et al. Long-term (12 months) treatment with an anti-oxidant drug (silymarin) is effective on hyperinsulinemia, exogenous insulin need and malondialdehyde levels in cirrhotic diabetic patients. J Hepatol 1997;26(4):871-879.
- Whittington C. Exacerbation of hemochromatosis by ingestion of milk thistle. Can Fam Physician 2007 Oct;53(10):1671-3.
- Zuber R, Modriansky M, Dvorak Z, et al. Effect of silybin and its congeners on human liver microsomal cytochrome P450 activities. Phytother Res 2002;16(7):632-638.
Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to . Selected references are listed below.