Milk thistle's use as a liver tonic goes back nearly 2,000 years, writes James A. Duke in "The Green Pharmacy Herbal Handbook." Medical texts by Culpepper, Gerard and Westmacott, writing in the 16th and 17th centuries, recommended milk thistle seeds and leaves to treat ailments of the liver, according to Maud Grieve, author of "A Modern Herbal."
Traditional herbalists may prescribe milk thistle seeds, extract or a tea made from milk thistle leaves to treat jaundice, hepatitis, cirrhosis, mushroom poisoning, diabetes, diabetic neuropathy, breast milk insufficiency and colic, according to Duke.
The German Commission E, which studies herbal and complementary treatments for the German government, approves milk thistle for the treatment of liver damage from toxins, cirrhosis and for chronic inflammation of the liver.
People who are allergic to ragweed, marigold, daisies and other members of the aster family may have allergic reactions to milk thistle and milk thistle supplements. Milk thistle may lower your blood sugar. Always discuss any herbal supplements or treatments with your doctor.