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...
Insufficient Evidence to Rate Effectiveness for...
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.
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.
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) 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)
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.
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)
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)
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)
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.
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)
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)
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)
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).
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).
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).
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).
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:
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.
Natural Medicines disclaims any responsibility related to medical consequences of using any medical product. Effort is made to ensure that the information contained in this monograph is accurate at the time it was published. Consumers and medical professionals who consult this monograph are cautioned that any medical or product related decision is the sole responsibility of the consumer and/or the health care professional. A legal License Agreement sets limitations on downloading, storing, or printing content from this Database. Except for any possible exceptions written into your License Agreement, no reproduction of this monograph or any content from this Database is permitted without written permission from the publisher. Unlawful to download, store, or distribute content from this site.
For the latest comprehensive data on this and every other natural medicine, health professionals should consult the Professional Version of the Natural Medicines. It is fully referenced and updated daily.
© Copyright 1995-2019. Therapeutic Research Faculty, publishers of Natural Medicines, Prescriber's Letter, and Pharmacist's Letter. All rights reserved.
Discover the different ways you can help
1-877 GO KOMEN(1-877-465-6636)
Give hope to others in your situation