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Milk Thistle (Silybum marianum)

Milk Thistle (Silybum marianum)

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.


Milk thistle is a plant that is native to Europe and was brought to North America by early colonists. Milk thistle is now found throughout the eastern United States, California, and South America. The plant grows up to 2 meters high and has large, bright purple flowers.

Milk thistle gets its name from the milky sap that comes out of the leaves when they are broken. The leaves also have unique white markings that, according to legend, were the Virgin Mary's milk. The above ground parts and seeds are used to make medicine. The seeds are more commonly used.

Milk thistle is taken by mouth most often for liver disorders, including liver damage caused by chemicals, alcohol, and chemotherapy, as well as liver damage caused by Amanita phalloides (death cap) mushroom poisoning, jaundice, chronic inflammatory liver disease, cirrhosis of the liver, and chronic hepatitis.

Milk thistle is also taken by mouth for loss of appetite, heartburn (dyspepsia), gallbladder complaints, enlarged prostate (benign prostatic hyperplasia), a blood disorder called beta-thalassemia, and infertility.

Some people take milk thistle by mouth for diabetes, kidney damage caused by diabetes, hangover, diseases of the spleen, prostate cancer, inflammation in the lungs and chest, malaria, depression, uterine complaints, increasing breast milk flow, allergy symptoms, starting menstrual flow, obsessive-compulsive disorder (OCD), Alzheimer's disease, Parkinson's disease, multiple sclerosis, high cholesterol, and menopausal symptoms.

People apply milk thistle to the skin for skin toxicity caused by radiation.

People use milk thistle intravenously (by IV) for Amanita phalloides (death cap) mushroom poisoning.

In foods, milk thistle leaves and flowers are eaten as a vegetable for salads and a substitute for spinach. The seeds are roasted for use as a coffee substitute.

Don't confuse milk thistle with blessed thistle (Cnicus benedictus).

How does it work?

Milk thistle seed might protect liver cells from toxic chemicals and drugs. It also seems to have antioxidant and anti-inflammatory effects.

Traditionally used for

Heartburn (dyspepsia).
Liver disease caused by excessive use of alcohol.
Seasonal allergies.
Alzheimer's disease.
Amanita mushroom poisoning.
Enlarged prostate (benign prostatic hyperplasia).
Blood disorder called beta-thalassemia.
Chemotherapy toxicity.
Liver scarring (cirrhosis).
Kidney disease in people with diabetes.
Menopausal symptoms.
Multiple sclerosis.
Nonalcoholic fatty liver disease (NAFLD).
Obsessive-compulsive disorder (OCD).
Parkinson's disease.
Skin toxicity caused by radiation.
Liver damage caused by chemicals.
Spleen disorders.
Gallbladder problems.
Swelling of the lungs (pleurisy).
Pain in the uterus.
Menstrual problems.
Low breast milk.


For diabetes: 200 mg of a specific product (Legalon, Madaus GmbH, Cologne, Germany) has been taken three times daily for 4 months to one year. 200 mg of a different silymarin product (Luna Co., Cairo, Egypt) has been daily for 120 days.

For upset stomach (dyspepsia): 1 mL of a specific combination product (Iberogast, Medical Futures, Inc) containing milk thistle and several other herbs has been used three times daily for 4 weeks.

Possible Side Effects

Milk thistle extract is SAFE when taken by mouth for most adults. Milk thistle sometimes causes a laxative effect. Other less common side effects are nausea, diarrhea, indigestion, intestinal gas, bloating, fullness or pain, and loss of appetite.

There isn't enough reliable information available to know if milk thistle is safe to apply to the skin or inject into the body.

Special Precautions & Warnings

Pregnancy and breast-feeding: There is not enough reliable information about the safety of taking milk thistle if you are pregnant or breast feeding. Stay on the safe side and avoid use.

Allergy to ragweed and related plants: Milk thistle may cause an allergic reaction in people who are sensitive to the Asteraceae/Compositae plant family. Members of this family include ragweed, chrysanthemums, marigolds, daisies, and many others. If you have allergies, be sure to check with your healthcare provider before taking milk thistle.

Diabetes: Certain chemicals in milk thistle might lower blood sugar in people with diabetes. Dosing adjustments to diabetes medications might be necessary.

Hormone-sensitive conditions such as breast cancer, uterine cancer, ovarian cancer, endometriosis, or uterine fibroids: Milk thistle extracts might act like estrogen. If you have any condition that might be made worse by exposure to estrogen, don't use these extracts.

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