Common Names: milk thistle, Mary thistle, holy thistle
Latin Names: Silybum marianum, synonym Carduus marianus
- Milk thistle is native to Europe and was introduced into North America by early colonists. Milk thistle is found throughout the eastern United States, California, South America, Africa, Australia, and Asia.
- The terms “milk thistle” and “silymarin” are often used interchangeably.
- Historically, people have used milk thistle for liver disorders and gallbladder problems.
- Milk thistle is promoted as a dietary supplement for hepatitis, cirrhosis, jaundice, diabetes, indigestion, and other conditions.
How Much Do We Know?
- We know little about whether milk thistle is effective in people, as only a few well-designed clinical studies have been conducted.
What Have We Learned?
- Results from clinical trials of milk thistle for liver diseases have been conflicting or haven’t been clinically meaningful. Some of the studies have been of poor quality, too.
- Although some studies have shown positive results on milk thistle for people with chronic hepatitis C virus (HCV) infection, the overall research does not show a benefit.
- A small number of studies have suggested that milk thistle extract might be beneficial for diabetes, but the conclusions about its effectiveness are not definite.
- It’s not known whether milk thistle is helpful for other conditions.
What Do We Know About Safety?
- In clinical trials, milk thistle appears to be well tolerated in recommended doses. Occasionally, people report various digestive 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).
- Milk thistle may lower blood sugar levels in people with type 2 diabetes. People with diabetes should use caution.
- Little is known about whether it’s safe to use milk thistle during pregnancy or while breastfeeding.
Keep in Mind
- Take charge of your health—talk with your health care providers about any complementary health approaches you use. Together, you can make shared, well-informed decisions.
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- Abenavoli L, Izzo AA, Millić N, et al. Milk thistle (Silybum marianum): a concise overview of its chemistry, pharmacological and nutraceutical uses in liver diseases. Phytotherapy Research. 2018;32(11):2202-2213.
- Camini FC, Costa DC. Silymarin: not just another antioxidant. Journal of Basic and Clinical Physiology and Pharmacology. 2020;31(4): :/j/jbcpp.2020.31.issue-4/jbcpp-2019-0206/jbcpp-2019-0206.xml.
- de Avelar CR, Pereira EM, de Farias Costa PR, et al. Effect of silymarin on biochemical indicators in patients with liver disease: systematic review with meta-analysis. World Journal of Gastroenterology. 2017;23(27):5004-5017.
- Milk Thistle. Natural Medicines website. Accessed at naturalmedicines.therapeuticresearch.com on April 1, 2020. [Database subscription].
- Tajmohammadi A, Razavi BM, Hosseinzadeh H. Silybum marianum (milk thistle) and its main constituent, silymarin, as a potential therapeutic plant in metabolic syndrome: a review. Phytotherapy Research. 2018;32(10):1933-1949.
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