The Who, What, Where, When and Sometimes, Why.

Milk thistle

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

Milk thistle is also taken by mouth for heartburn (dyspepsia), inflammatory bowel disease (ulcerative colitis), enlarged prostate (benign prostatic hyperplasia), a blood disorder called beta-thalassemia, and infertility.

Some people also take milk thistle by mouth for diabetes, kidney damage caused by diabetes or contrast media use, prostate cancer, to decrease the side effects of chemotherapy and radiation, uterine complaints, increasing breast milk flow, allergy symptoms, starting menstrual flow, obsessive-compulsive disorder (OCD), Alzheimer’s disease, Parkinson’s disease, multiple sclerosis (MS), high cholesterol, and menopausal symptoms.

Some people apply milk thistle directly 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). 

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.

The Effectiveness ratings for Milk Thistle are as follows:

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.
  • Heartburn (dyspepsia). When used daily for 4 weeks, a specific combination product (Iberogast by Medical Futures, Inc.) that contains milk thistle plus eight other ingredients seems to reduce the severity of acid reflux, stomach pain, cramping, nausea, and vomiting.

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. Early research shows that taking milk thistle by mouth might improve liver function and reduce risk of death. However, other research shows no benefit.
  • Seasonal allergies. 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.
  • Alzheimer’s disease. Early research shows that taking a combination supplement containing milk thistle extract improves mental function in people with Alzheimer’ s disease.
  • Amanita mushroom poisoning. Early research shows that giving silibinin, a chemical found in milk thistle, intravenously (by IV) and then by mouth may lessen liver damage caused by Amanita phalloides mushroom (death cap) poisoning. However, it is hard to obtain silibinin in the US.
  • Enlarged prostate (benign prostatic hyperplasia). Early research shows that taking a specific combination of milk thistle extract and selenium for 6 months might improve symptoms of enlarged prostate in men.
  • Blood disorder called beta-thalassemia. Early research in children with the blood disorder beta-thalassemia 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.
  • Hand-foot syndrome. 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 a complication of chemotherapy called hand-foot syndrome.
  • Chemotherapy toxicity. 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 the chemotherapy drug cisplatin. 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. Early research shows that taking milk thistle extract together with conventional treatment might help treat kidney disease in people with diabetes.
  • 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 product containing the milk thistle constituent silybin plus phosphatidylcholine by mouth for 2 weeks to 3 months might improve some liver function tests.
  • 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.
  • 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 cholesterol. Taking milk thistle along with tree turmeric seems to prevent cholesterol levels from increasing in people with high cholesterol who are taking statins but who require their statin dose to be lowered. Taking this product also seems to help lower cholesterol when used alone or along with low-dose statins or ezetimibe in people with high cholesterol who can’t tolerate high dose statin treatment. It’s unclear if these benefits are due to milk thistle, tree turmeric, or the combination. There is also evidence that taking a similar product containing milk thistle, tree turmeric, and chemicals called monacolins also helps to lower cholesterol levels. Monacolins are chemicals similar to statin drugs. So, it’s not clear if the cholesterol reduction is due to milk thistle or the statin-like chemicals.
  • High levels of fat particles (lipids) in the blood. Taking milk thistle doesn’t seem to lower lipid levels in the blood in people with high levels due to liver disease.
  • 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.
  • Low milk production. Early research shows that taking milk thistle extract for 4 weeks does not increase milk production in mothers of premature infants.
  • Menopausal symptoms. Research shows that taking a specific combination product containing milk thistle and other ingredients by mouth for 3 months reduces hot flashes by 73% and night sweats by 69% in people with menopausal symptoms. Sleep quality also improves. It’ s not clear if these benefits are due to milk thistle or other ingredients.
  • Multiple sclerosis (MS). Early research shows that taking a combination supplement containing milk thistle extract can improve mental function and increase disease stabilization in people with multiple sclerosis.
  • Liver disease not caused by alcohol (nonalcoholic fatty liver disease; 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.
  • Obsessive-compulsive disorder (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.
  • Parkinson’s disease. Early research shows that taking a combination supplement containing milk thistle extract improves mental function and increases disease stabilization in people with Parkinson’s disease.
  • Prostate cancer. Prostate-specific antigen (PSA) is a protein in the blood that can be measured to diagnose and monitor prostate cancer. Early research shows that taking a supplement containing milk thistle extract, soy isoflavones, lycopene, vitamins, minerals and antioxidants by mouth daily can delay the rise in PSA levels in men with a history of prostate cancer. The effects of milk thistle alone are not clear.
  • 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 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 or those taking 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.
  • Inflammation of the digestive tract (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.
  • Depression.
  • Gallbladder problems.
  • Hangover.
  • Kidney damage caused by contrast media.
  • Low breast milk.
  • Malaria.
  • Menstrual problems.
  • Pain in the uterus.
  • Spleen disorders.
  • Swelling of the lungs (pleurisy).
  • Other conditions.

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

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

Milk thistle extractis LIKELY 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: 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.

Estrogens

Interaction Rating = Minor Be watchful with this combination.

Talk to your health provider.

Milk thistle might decrease the effects of estrogen pills by blocking how estrogen works in the body.

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

Indinavir (Reyataz)

Interaction Rating = Minor Be watchful with this combination.

Talk to your health provider.

Indinavir (Reyataz) is a drug that is changed and broken down by the liver. Milk thistle might increase how quickly the liver breaks down some medications. But milk thistle does not seem to affect how quickly the body breaks down indinavir (Reyataz).

Medications changed by the liver (Cytochrome P450 1A2 (CYP1A2) substrates)

Interaction Rating = Minor Be watchful with this combination.

Talk to your health provider.

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 might increase the effects and side effects of these 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 clozapine (Clozaril), cyclobenzaprine (Flexeril), fluvoxamine (Luvox), haloperidol (Haldol), imipramine (Tofranil), mexiletine (Mexitil), olanzapine (Zyprexa), pentazocine (Talwin), propranolol (Inderal), tacrine (Cognex), theophylline, zileuton (Zyflo), zolmitriptan (Zomig), and others.

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

Interaction Rating =  Minor Be watchful with this combination.

Talk to your health provider.

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 might increase the effects and side effects of these 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 2D6 (CYP2D6) substrates)

Interaction Rating =  Minor Be watchful with this combination.

Talk to your health provider.

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 might increase the effects and side effects of these 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 imipramine (Tofranil) and amitriptyline (Elavil); antipsychotics such as haloperidol (Haldol), risperidone (Risperdal), and chlorpromazine (Thorazine); beta-blockers such as propranolol (Inderal), metoprolol (Lopressor, Toprol XL), and carvedilol (Coreg); tamoxifen (Nolvadex); and others.

Medications changed by the liver (Cytochrome P450 3A4 (CYP3A4) substrates)

Interaction Rating =  Minor Be watchful with this combination.

Talk to your health provider.

Some medications are changed and broken down by the liver. Milk thistle might affect how quickly the liver breaks down some medications. Taking milk thistle along with some medications that are broken down by the liver might increase or decrease the effects of these 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), alprazolam (Xanax), amlodipine (Norvasc), clarithromycin (Biaxin), cyclosporine (Sandimmune), erythromycin, verapamil (Calan, Isoptin) and many others.

Medications changed by the liver (Cytochrome P450 3A5 (CYP3A5) substrates)

Interaction Rating = Minor Be watchful with this combination.

Talk to your health provider.

Some medications are changed and broken down by the liver. Milk thistle might affect how quickly the liver breaks down some medications. Taking milk thistle along with some medications that are broken down by the liver might increase or decrease the effects of these 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 testosterone, progesterone (Endometrin, Prometrium), nifedipine (Adalat CC, Procardia XL), cyclosporine (Sandimmune), and others.

Medications changed by the liver (Glucuronidated drugs)

Interaction Rating = Moderate Be cautious with this combination.

Talk to your health provider.

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 might increase or decrease how well some of these medications work.

Some of these medications changed by the liver include acetaminophen (Tylenol, others) and oxazepam (Serax), haloperidol (Haldol), lamotrigine (Lamictal), morphine (MS Contin, Roxanol), zidovudine (AZT, Retrovir), and others.

Medications for diabetes (Antidiabetes drugs)

Interaction Rating = Moderate Be cautious with this combination.

Talk to your health provider.

Milk thistle can lower blood sugar levels. Taking milk thistle along with diabetes medications might cause your blood sugar to be too low. Monitor your blood sugar closely. The dose of your diabetes medication might need to be changed.

Some medications used for diabetes include glimepiride (Amaryl), glyburide (DiaBeta, Glynase PresTab, Micronase), insulin, metformin (Glucophage), pioglitazone (Actos), rosiglitazone (Avandia), and others.

Medications moved by pumps in cells (P-Glycoprotein Substrates)

Interaction Rating = Moderate Be cautious with this combination.

Talk to your health provider.

Some medications are moved by pumps in cells. Milk thistle might make these pumps less active and increase how much of some medications get absorbed by the body. This might cause more side effects from some medications.

Some medications that are moved by these pumps include etoposide, paclitaxel, vinblastine, vincristine, vindesine, ketoconazole, itraconazole, amprenavir, indinavir, nelfinavir, saquinavir, cimetidine, ranitidine, diltiazem, verapamil, digoxin, corticosteroids, erythromycin, cisapride (Propulsid), fexofenadine (Allegra), cyclosporine, loperamide (Imodium), quinidine, and others.

Medications used for lowering cholesterol (Statins)

Interaction Rating = Minor Be watchful with this combination.

Talk to your health provider.

Theoretically, milk thistle might change the levels of some medications used for lowering cholesterol (statins). This might decrease how well these medications work.

Some medications used for lowering cholesterol include atorvastatin (Lipitor), fluvastatin (Lescol), lovastatin (Mevacor), pravastatin (Pravachol), and rosuvastatin (Crestor).

Raloxifene (Evista)

Interaction Rating = Moderate Be cautious with this combination.

Talk to your health provider.

Taking milk thistle might decrease how well the body breaks down raloxifene (Evista) in the intestines. This might increase the effects and side effects of raloxifene (Evista). Before taking milk thistle, talk to your healthcare provider if you are taking raloxifene (Evista).

Sirolimus (Rapamune)

Interaction Rating = Moderate Be cautious with this combination.

Talk to your health provider.

Taking milk thistle might decrease how well the liver breaks down sirolimus (Rapamune). This might increase the effects and side effects of sirolimus (Rapamune). Before taking milk thistle, talk to your healthcare provider if you are taking sirolimus (Rapamune).

Tamoxifen (Nolvadex)

Interaction Rating = Moderate Be cautious with this combination.

Talk to your health provider.

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

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.

There are no known interactions with foods.

The following doses have been studied in scientific research:

BY MOUTH:

  • 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.

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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