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Milk Thistle


Laura Shane-McWhorter

, PharmD, University of Utah College of Pharmacy

Last full review/revision Jul 2020| Content last modified Jul 2020
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Milk thistle is a purple-flowered plant. Its sap and seeds contain the active ingredient silymarin, a potent antioxidant and a term often used interchangeably with milk thistle. (See also Overview of Dietary Supplements.)

Medicinal claims

Milk thistle is claimed to protect the liver from damage by viruses, toxic substances (such as alcohol and the toxins from death cap mushrooms), and certain drugs that are toxic to the liver (such as acetaminophen). Thus, people take milk thistle to prevent and treat mushroom poisoning and other liver disorders, such as cirrhosis and hepatitis C. Well-designed scientific studies do not show that milk thistle significantly benefits people with a liver disorder or decreases death due to liver toxicity.

Milk thistle also may cause a slight to moderate decrease in blood glucose and hemoglobin A1c in people with type 2 diabetes.

Possible side effects

No serious side effects have been reported.

Women who have hormone-sensitive conditions (such as breast, uterine, or ovarian cancer, endometriosis, or uterine fibroids) should avoid the above-ground parts of milk thistle.

Possible drug interactions

Milk thistle may intensify the effects of drugs that decrease blood sugar levels (hypoglycemic drugs) and may interfere with drugs used to treat human immunodeficiency virus (HIV) infection (such as indinavir or saquinavir).

More Information about Milk Thistle

The following is an English-language resource that may be useful. Please note that THE MANUAL is not responsible for the content of this resource.

NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
Click here for the Professional Version
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