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From the National Institutes of HealthNational Institutes of Health

Milk thistle


What is it?

Milk thistle is a plant. The above ground parts and seeds are used to make medicine. The seeds are more commonly used.

Milk thistle is used most often for liver disorders, including liver damage caused by chemicals, Amanita phalloides mushroom poisoning, jaundice, chronic inflammatory liver disease, cirrhosis of the liver, and chronic hepatitis. Nevertheless, researchers have not yet concluded with certainty that milk thistle is effective for any of these uses.

Milk thistle is also used for loss of appetite, heartburn (dyspepsia), and gallbladder complaints.

Some people use milk thistle for diabetes, hangover, diseases of the spleen, prostate cancer, malaria, depression, uterine complaints, increasing breast milk flow, allergy symptoms, and starting menstrual flow.

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.

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

How effective is it?

Natural Medicines Comprehensive Database rates effectiveness based on scientific evidence according to the following scale: Effective, Likely Effective, Possibly Effective, Possibly Ineffective, Likely Ineffective, Ineffective, and Insufficient Evidence to Rate.

The effectiveness ratings for MILK THISTLE are as follows:

Possibly effective for...

  • Seasonal allergies (allergic rhinitis). Some research shows that people who take a milk thistle extract in combination with a conventional antihistamine have reduced symptoms compared to people who just use an antihistamine.
  • Heartburn (dyspepsia), when a combination of milk thistle and several other herbs is used. The combination product (Iberogast, Medical Futures, Inc) contains milk thistle plus peppermint leaf, German chamomile, caraway, licorice, clown’s mustard plant, celandine, angelica, and lemon balm. When used daily over a period of 4 weeks, this combination seems to reduce severity of acid reflux, stomach pain, cramping, nausea, and vomiting.
Most studies of milk thistle’s effectiveness have used a specific extract standardized to 70% to 80% silymarin. In the U.S., this formulation is found in the brand name product Thisilyn (Nature’s Way).

Insufficient evidence to rate effectiveness for...

  • Liver disease caused by excessive use of alcohol. There is conflicting evidence about the effectiveness of milk thistle for treating alcohol-related liver disease.
  • Amanita mushroom poisoning. Giving silibinin, a chemical found in milk thistle, intravenously (by IV) may lessen liver damage due to Amanita phalloides mushroom (death cap) poisoning. However, it is hard to get silibinin in the U.S.
  • Hepatitis B or hepatitis C. Milk thistle and some of the chemicals in it do not seem to improve survival or decrease liver function tests in people with hepatitis B or C.
  • Liver disease caused by chemicals. Some research suggests milk thistle may limit liver damage after exposure to industrial poisons such as toluene and xylene.
  • Spleen disorders.
  • Gallbladder problems.
  • Swelling of the lungs (pleurisy).
  • Malaria.
  • Menstrual problems.
  • Other conditions.
More evidence is needed to rate the effectiveness of milk thistle for these uses.

How does it work?

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Milk thistle seed might protect liver cells from toxic chemicals and drugs. It also seems to have antioxidant and anti-inflammatory effects. Milk thistle plant extract might enhance the effects of estrogen.

Are there safety concerns?

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Milk thistle is LIKELY SAFE 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.

Special precautions & warnings:

Pregnancy and breast-feeding: Not enough is known about the use of milk thistle during pregnancy and 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.

Hormone-sensitive conditions such as breast cancer, uterine cancer, ovarian cancer, endometriosis, or uterine fibroids: Extracts from milk thistle PLANT might act like estrogen. If you have any condition that might be made worse by exposure to estrogen, don’t use these extracts. In contrast, the more commonly used milk thistle SEED extracts do not seem to act like estrogen.

Are there interactions with medications?

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Moderate

Be cautious with this combination.

Medications changed by the liver (Cytochrome P450 2C9 (CYP2C9) substrates)
Some medications are changed and broken down by the liver. Milk thistle might decrease how quickly the liver breaks down some medications. Taking milk thistle along with some medications that are broken down by the liver can increase the effects and side effects of some medications. Before taking milk thistle, talk to your healthcare provider if you take any medications that are changed by the liver.

Some medications that are changed by the liver include amitriptyline (Elavil), diazepam (Valium), zileuton (Zyflo), celecoxib (Celebrex), diclofenac (Voltaren), fluvastatin (Lescol), glipizide (Glucotrol), ibuprofen (Advil, Motrin), irbesartan (Avapro), losartan (Cozaar), phenytoin (Dilantin), piroxicam (Feldene), tamoxifen (Nolvadex), tolbutamide (Tolinase), torsemide (Demadex), warfarin (Coumadin), and others.

Medications changed by the liver (Cytochrome P450 3A4 (CYP3A4) substrates)
Some medications are changed and broken down by the liver. Milk thistle might decrease how quickly the liver breaks down some medications. Taking milk thistle along with some medications that are broken down by the liver can increase the effects and side effects of some medications. Before taking milk thistle, talk to your healthcare provider if you take any medications that are changed by the liver.

Some medications changed by the liver include lovastatin (Mevacor), ketoconazole (Nizoral), itraconazole (Sporanox), fexofenadine (Allegra), triazolam (Halcion), and many others.

Medications changed by the liver (Glucuronidated drugs)
The body breaks down some medications to get rid of them. The liver helps break down these medications. Taking milk thistle might affect how well the liver breaks down drugs. This could increase or decrease how well some of these medications work.

Some of these medications changed by the liver include acetaminophen, atorvastatin (Lipitor), diazepam (Valium), digoxin, entacapone (Comtan), estrogen, irinotecan (Camptosar), lamotrigine (Lamictal), lorazepam (Ativan), lovastatin (Mevacor), meprobamate, morphine, oxazepam (Serax), and others.

Tamoxifen (Nolvadex)
Milk thistle might increase how much tamoxifen is absorbed by the body. Before taking milk thistle, talk to your healthcare provider if you are taking tamoxifen.

Minor

Be watchful with this combination.

Estrogens
Milk thistle might decrease hormones in the body. Milk thistle might help the body break down estrogen pills to get rid of them. Taking milk thistle along with estrogens might decrease the effectiveness of estrogen pills. Milk thistle contains a chemical called silymarin. Silymarin might be the part of milk thistle that helps the body break down estrogens.

Some estrogen pills include conjugated equine estrogens (Premarin), ethinyl estradiol, estradiol, and others.

Medications used for lowering cholesterol (Statins)
Theoretically, milk thistle might change the levels of some medications used for lowering cholesterol (statins). This could increase or decrease how well these medications work.
Some medications used for lowering cholesterol include atorvastatin (Lipitor), fluvastatin (Lescol), lovastatin (Mevacor), pravastatin (Pravachol), and rosuvastatin (Crestor).

Are there interactions with herbs and supplements?

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There are no known interactions with herbs and supplements.

Are there interactions with foods?

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There are no known interactions with foods.

What dose is used?

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The following doses have been studied in scientific research:

BY MOUTH:
  • For seasonal allergies (allergic rhinitis): Milk thistle extract of silymarin 140 mg three times daily.
  • For upset stomach (dyspepsia): A specific combination product containing milk thistle (Iberogast, Medical Futures, Inc) and several other herbs has been used in a dose of 1 mL three times daily.

Other names

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Artichaut Sauvage, Blessed Milk Thistle, Cardo Lechoso, Cardui Mariae Fructus, Cardui Mariae Herba, Carduus Marianum, Carduus marianus, Chardon Argenté, Chardon de Marie, Chardon de Notre-Dame, Chardon Marbré, Chardon-Marie, Épine Blanche, Holy Thistle, Lady's Thistle, Lait de Notre-Dame, Legalon, Marian Thistle, Mariendistel, Mary Thistle, Our Lady's Thistle, Shui Fei Ji, Silibinin, Silybe de Marie, Silybin, Silybum, Silybum marianum, Silymarin, Silymarine, St. Mary Thistle, St. Marys Thistle.

Methodology

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To learn more about how this article was written, please see the Natural Medicines Comprehensive Database methodology.methodology (http://www.nlm.nih.gov/medlineplus/druginfo/natural/methodology.html).

References

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To see all references for the Milk thistle page, please go to http://www.nlm.nih.gov/medlineplus/druginfo/natural/138.html.

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Last reviewed - 08/17/2012

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Page last updated: 06 September 2012