Milk Thistle

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What is it?

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, South America, Africa, Australia, and Asia. The above ground parts and seeds are used to make medicine.

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 mushroom poisoning, nonalcoholic fatty liver disease, chronic inflammatory liver disease, cirrhosis of the liver, and chronic hepatitis.

Some people apply milk thistle directly to the skin for skin damage caused by radiation.

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).

It is effective?
Natural Medicines 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.

Possibly Effective for …

  • Diabetes. Taking milk thistle extract or milk thistle extract plus tree turmeric extract along with antidiabetes drugs seems to decrease blood sugar levels before meals in people with diabetes. It also seems to decrease average blood sugar levels in these people. It might take more than 3 months for milk thistle products to show benefit. Specific milk thistle products used in research include Livergol by Goldaru Herbal Products and Berberol by PharmExtracta.

Insufficient Evidence to Make a Determination for …

  • Acne. Taking milk thistle might lessen acne severity. But the benefits, if any, are small.
  • Liver disease in people who drink alcohol. There is conflicting evidence about the effectiveness of milk thistle for treating alcohol-related liver disease. Early research shows that taking milk thistle by mouth might improve liver function and reduce risk of death. However, other research shows no benefit.
  • Mushroom poisoning. Early research shows that giving silibinin, a chemical found in milk thistle may lessen liver damage caused by Amanita phalloides mushroom (death cap mushroom) poisoning. However, it is hard to obtain silibinin in the US.
  • A blood disorder that reduces levels of protein in the blood called hemoglobin (beta-thalassemia). Early research in children with this blood disorder shows that taking a specific milk thistle extract for 6-9 months, along with conventional medicine, might decrease iron levels better than conventional medicine alone.
  • An adverse skin reaction caused by cancer drug treatment (chemotherapy-induced acral erythema). Early research shows that applying a gel containing milk thistle extract to the hands and feet beginning on the first day of chemotherapy and continuing for 9 weeks decreases the severity of this skin reaction caused by a cancer drug called capecitabine.
  • Liver damage caused by cancer drugs. Early research shows that taking a specific milk thistle product containing the chemical silibinin beginning at the start of chemotherapy treatment does not significantly reduce liver toxicity caused by chemotherapy.
  • Kidney damage caused by cancer drugs. Early research shows that taking milk thistle extract beginning 24-48 hours before starting therapy with cisplatin, and continuing until the end of the treatment course, does not prevent or decrease the rates of kidney injury.
  • Liver scarring (cirrhosis). Early research shows that milk thistle extract might reduce the risk of death and improve liver function in people with cirrhosis. However, milk thistle extract does not seem to benefit all patients with liver disease.
  • Kidney disease in people with diabetes (diabetic nephropathy). Early research shows that taking milk thistle extract together with conventional treatment might help treat kidney disease in people with diabetes.
  • Hay fever. Some research shows that taking milk thistle extract by mouth along with the allergy medication cetirizine (Zyrtec) reduces seasonal allergies more than taking cetirizine alone.
  • Swelling (inflammation) of the liver (hepatitis). Research on the effects of milk thistle in people with hepatitis is not consistent. Some research shows that taking milk thistle extract by mouth for 4 weeks reduces hepatitis symptoms, such as dark urine and jaundice, but does not improve liver function tests. But taking a product containing the milk thistle constituent silybin plus phosphatidylcholine by mouth for 2 weeks to 3 months might improve some liver function tests.
  • Swelling (inflammation) of the liver caused by the hepatitis B virus (hepatitis B). Research on the effects of milk thistle in people with hepatitis B is not consistent. Early research shows that taking milk thistle extract by mouth for up to one year, or taking a product containing the milk thistle constituent silybin plus phosphatidylcholine by mouth for 1 week, improves liver function tests. But other research shows no benefit.
  • Swelling (inflammation) of the liver caused by the hepatitis C virus (hepatitis C). Research on the effects of milk thistle in people with hepatitis C is inconsistent. Early research shows that taking milk thistle extract by mouth for up to one year, or taking a product containing the milk thistle constituent silybin plus phosphatidylcholine by mouth for 1 week, improves liver function tests. But other research shows no benefit.
  • High levels of lipoproteins in the blood (hyperlipoproteinemia). Taking milk thistle doesn’t seem to lower lipid levels in the blood in people with high levels due to liver disease.
  • Liver damage caused by low oxygen levels. Early research shows that taking milk thistle extract might reduce liver damage caused by low levels of oxygen in the blood.
  • Inability to become pregnant within a year of trying to conceive (infertility). Early research shows that taking milk thistle extract along with fertility hormones might provide some benefits for women undergoing in vitro fertilization due to male infertility.
  • Breast feeding. Early research shows that taking milk thistle extract for 4 weeks does not increase milk production in mothers of premature infants.
  • Build-up of fat in the liver in people who drink little or no alcohol (nonalcoholic fatty liver disease or NAFLD). There is evidence that milk thistle extract improves markers of liver injury in people with NAFLD. But these markers aren’t always linked with the NAFLD severity. Most experts recommend that people with NAFLD lose weight to reduce fat build-up in the liver and lower their cholesterol to reduce the risk of heart disease. Taking milk thistle does not seem to improve either of these outcomes. But there is some evidence that milk thistle might benefit people with a severe form of NAFLD called nonalcoholic steatohepatitis (NASH). While taking milk thistle doesn’t seems to improve the overall severity of NASH, it does seem to reduce scarring of the liver.
  • Swelling (inflammation) and build up of fat in the liver in people who drink little or no alcohol (nonalcoholic steatohepatitis or NASH). While taking milk thistle doesn’t seems to improve the overall severity of NASH, it does seem to reduce scarring of the liver.
  • A type of anxiety marked by recurrent thoughts and repetitive behaviors (obsessive-compulsive disorder or OCD). Early research shows that taking milk thistle leaf extract by mouth three times daily for 8 weeks has a limited effect on OCD symptoms. It does not appear to more beneficial than conventional medication.
  • Skin toxicity caused by radiation. Early research shows that applying a specific product containing the milk thistle extract reduces the effect of radiation on the skin in women being treated for breast cancer.
  • Inflammation and ulcers (mucositis) caused by radiation. Early research shows that taking milk thistle extract starting on the first day of radiation and continuing for 6 weeks thereafter decreases the severity of ulcers in the mouth and gut caused by radiation.
  • Liver damage caused by chemicals. The effect of milk thistle on liver damage caused by chemicals is inconsistent. Taking milk thistle by mouth helps the liver to function in people who have been exposed to the chemicals toluene or xylene. It also seems to help the liver in people who take isotretinoin for acne or drugs for tuberculosis. But taking milk thistle extract by mouth does not seem to prevent liver damage associated with the drug tacrine (Cognex) in people with Alzheimer’s disease.
  • Hair pulling (trichotillomania). Early research shows that milk thistle taken for 6 weeks does not reduce the symptoms of hair pulling.
  • A type of inflammatory bowel disease (ulcerative colitis). Early research shows that taking milk thistle extract by mouth for 6 months, in addition to standard medications, decreases the symptoms of ulcerative colitis and helps maintain remission.
  • A skin disorder that causes white patches to develop on the skin (vitiligo). Early research shows that taking the milk thistle constituent silymarin along with phototherapy for 3 months is no better than phototherapy alone for improving vitiligo severity.
  • Alzheimer disease.
  • Enlarged prostate (benign prostatic hyperplasia or BPH).
  • High cholesterol.
  • Indigestion (dyspepsia).
  • Kidney damage caused by contrast dyes (contrast induced nephropathy).
  • Multiple sclerosis (MS).
  • Parkinson disease.
  • Prostate cancer.
  • Symptoms of menopause.
  • Other conditions.

More evidence is needed to rate the effectiveness of milk thistle for these uses.

How does it work?
Milk thistle seed might protect liver cells from toxic chemicals and drugs. It also seems to have blood sugar-lowering, antioxidant, and anti-inflammatory effects.

Is there concern for the safety of its use?
When taken by mouth: Milk thistle extract is LIKELY SAFE for most people when taken by mouth. In some people, taking milk thistle extract can cause diarrhea, nausea, intestinal gas, fullness, loss of appetite, and possibly headache.

When applied to the skin: Milk thistle extract is POSSIBLY SAFE when applied directly to the skin for short periods of time.

Special Precautions & Warnings:

Pregnancy and breast-feeding: There isn’t enough reliable information to know if milk thistle is safe to use when pregnant or breast-feeding. Stay on the safe side and avoid use.

Children: Milk thistle is POSSIBLY SAFE when taken by mouth, appropriately, for up to 9 months in children 1 year of age and older.

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: 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.

Are there any drug interactions?

Estrogens

Interaction Rating=Minor Be watchful with this combination.

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 changed by the liver (Cytochrome P450 2C9 (CYP2C9) substrates)

Interaction Rating=Moderate Be cautious with this combination.

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 (Glucuronidated Drugs)

Interaction Rating=Moderate Be cautious with this combination.

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.

Medications used for lowering cholesterol (Statins)

Interaction Rating=Minor Be watchful with this combination.

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 any interactions with herbs and supplements?
Herbs and supplements that might lower blood sugar: Milk thistle can lower blood glucose levels. Using it with other herbs or supplements that have the same effect might cause blood sugar levels to drop too low. Some herbs and supplements that can lower blood sugar include alpha-lipoic acid, bitter melon, chromium, devil’s claw, fenugreek, garlic, guar gum, horse chestnut, Panax ginseng, psyllium, Siberian ginseng, and others.

Are there any interactions with food?
There are no known interactions with foods.

What dose is used?
The following doses have been studied in scientific research:

ADULTS
BY MOUTH:

  • For diabetes: A specific product (Livergol, Goldaru Herbal Products Pharmaceutical Company) containing 140 mg of milk thistle extract has been taken three times daily for 45 days. 200 mg of milk thistle extract has been taken once daily or three times daily for 4 months to one year. A specific product (Berberol, PharmExtracta) containing 210 mg of milk thistle extract and 1176 mg of tree turmeric extract has been taken daily for 3-12 months.

By what other names is the product known?
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.

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