Herbal Monograph – Milk Thistle

Traditional uses of Milk Thistle

Herbal drugs have been used traditionally by physicians, herbalists and folk healers worldwide for the prevention and treatment of liver disease. Among medicinal plants, milk thistle (Silybum marianum) has been used for centuries as a natural remedy for upper gastrointestinal disturbances, for diseases of the liver and the gall bladder, as well as for menstrual disorders, varicose veins and other indications.


  • Liver Diseases

    Milk Thistle is one of the most widely researched herbs for the treatment of a range of liver diseases. Researchers have reviewed the history, pharmacology and properties of Milk Thistle, as well as the clinical trials in patients with acute and chronic liver disease and have concluded that Milk Thistle may be effective in improving the clinical courses of both acute and chronic, viral, drug, and alcohol-induced liver disorders1.

  • Milk Thistle Benefits Liver Cirrhosis Sufferers

    A study performed to determine the effect of Milk Thistle on the outcome of patients with cirrhosis of the liver looked at 170 patients presenting with cirrhosis. Of these, 87 patients were treated with 140mg of Milk Thistle three times daily, while the other 83 patients received a placebo. The patients were observed for a total of 41 months. In the placebo group, 31 individuals died of liver disease, while in the Milk Thistle treated group only 18 died of liver disease. The 4-year survival rate was 58% in Milk Thistle-treated patients and 39% in the placebo group. Analysis of subgroups of the patients indicated that treatment was most effective in patients with alcoholic cirrhosis2.

Anticarcinogenic effects of Milk Thistle

Milk Thistle has also has been found to prevent skin cancer in animals. The mechanism of the anti-carcinogenic effect of Milk Thistle was tested in mice. Tumour promoters (such as chemical toxins) have been shown to induce oxidative stress as one of the mechanisms of cancer promotion. Oxidative stress leads to the damage of DNA, lipids and proteins. Milk Thistle inhibits the depletion of antioxidant enzyme activities in the skin, which results in reduction of damaging oxidative stress. Thus Milk Thistle acts as a potent skin protective agent against cancer and free radical damage3.

Extensive studies with Milk Thistle and prostate cancer cells have shown anti-cancer effects leading to cell growth inhibition in vitro (test tubes). The underlying mechanisms of Milk Thistle efficacy against prostate cancer cells involve improving the way cells replicate, leading to a reduced incidence in cancer formation. Milk Thistle also synergises the therapeutic effects of some chemotherapeutic drugs in prostate cancer cells, making it a strong candidate for combination chemotherapy. Milk Thistle also inhibits the secretion of growth factors from tumour cells, and causes growth inhibition and cancer cell death. More importantly, Milk Thistle inhibits the growth of advanced human prostate tumours. Recently, due to its non-toxic and mechanism-based strong preventive/therapeutic efficacy, Milk Thistle was included in a Phase I clinical trial in prostate cancer patients.

Contraindications of Milk Thistle

Milk Thistle is generally regarded as a very safe herb however it should be avoided during pregnancy unless professionally prescribed. Although the adverse effect profile and tolerability of this herb are excellent, long-term safety studies are lacking4.

Drug Interaction with Milk Thistle

Although Milk Thistle, like any herbal medicine, can conflict with medications, no significant herb/drug interactions with Milk Thistle have been reported. However, we do advise that before using this herb or any other herbal preparation, to consult your health care professional.

Therapeutic/safe dosages of Milk Thistle

Most herbalists recommend the equivalent of 3-18 grams of dried Milk Thistle per day for therapeutic purposes. This equates to 75-450 mg of the principal active ingredient, Silybin. If using Milk Thistle capsules or tablets that have been standardized to contain 80% Silybin, the usual dosage is 200-1,050 mg per day (this equates to 160-840 mg of Silybin per day). It is desirable to take Milk Thistle supplements as three equally divided doses during the day.

Other herbs that can be used with Milk Thistle
As with many herbal preparations, herbs are often combined to make a formula. This formula usually contains herbs with a similar action thus improving the effectiveness over a single herbal preparation. Herbs that are commonly found with Milk Thistle include:

  • Dandelion Root. This herb does help restore proper functioning of the liver. Dandelion also increases bile flow from the gall bladder and bile production from the liver. Most herbalists suggest that while Milk Thistle is better for repairing damaged liver cells, Dandelion is better for cleaning the liver and increasing bile flow. Along with Milk Thistle, Dandelion will benefit people undergoing detoxification of the liver.

  • Schizandra. Well known for its beneficial effects on the central nervous system, Schizandra possesses highly beneficial effects on the liver. It works primarily as a liver rebuilding agent for conditions such as hepatitis and liver poisoning. Schizandra combines well with Milk Thistle for individuals with severe liver damage.

  • Green tea. Green tea is a widely researched herb which has been found to be beneficial for the prevention and treatment of most types of cancer, including prostate and skin cancers. Green tea also induces beneficial effects on the liver and antioxidant status in humans.


Milk Thistle is a highly prized herb and has been used for thousands of years for the treatment of gastrointestinal and liver disorders. More recently it has been found to be beneficial for the treatment of some cancers. Clinical trials now support these uses and there is weighty scientific data that supports the medicinal uses of this herb. While Milk Thistle is generally regarded as safe, interactions between this herb and medical drugs are possible. If you are on medication of any kind, please check with your health care professional before taking any herbs.


1. Flora K, H.M., Rosen H, et al., Milk thistle (Silybum marianum) for the therapy of liver disease. Am J Gastroenterol, 1998. 93: p. 139-43.
2. Ferenci P, D.B., Dittrich H, et al., Randomized controlled trial of Milk Thistle treatment in patients with cirrhosis of the liver. J Hepatol, 1989. 9: p. 105-113.
3. SK., K., Milk Thistle and skin cancer prevention: anti-inflammatory, antioxidant and immunomodulatory effects (Review). Int J Oncol., 2005. 26(1): p. 169-76.
4. Laekeman G, D.C.S., De Meyer K. K.U.Leuven., St. Mary's Thistle: an overview. J Pharm Belg., 2003. 58(1): p. 28-31.

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