Milk thistle is a purple-flowered plant. Its sap and seeds contain the active ingredient silymarin, a potent antioxidant.
Milk thistle is said to treat cirrhosis and to protect the liver from viral hepatitis, the damaging effects of alcohol, and hepatotoxic drugs. In vitro, silymarin increases levels of intrahepatic glutathione, an antioxidant important for detoxification. Well-designed studies do not show that milk thistle significantly benefits people with liver disease, although individual case reports claim fatality reduction in mushroom poisoning.
No serious adverse effects have been reported. Milk thistle may intensify the effects of antihyperglycemic drugs and may interfere with indinavir therapy. Women who have hormone-sensitive conditions (eg, breast, uterine, and ovarian cancer; endometriosis; and uterine fibroids) should avoid the above-ground parts of milk thistle.
Last full review/revision May 2009 by Ara DerMarderosian, PhD
Content last modified August 2013