It has been used for 2,000 years as an herbal remedy for a variety of ailments, particularly liver, kidney, and gall bladder problems. Several scientific studies suggest that substances in milk thistle (especially a flavonoid called silymarin) protect the liver from toxins, including drugs, such as acetaminophen (Tylenol), which can cause liver damage in high doses. It may have antioxidant and anti-inflammatory properties, protecting against cancer, diabetes and high cholesterol.
Milk thistle is generally regarded as safe. It can sometimes act as a laxative, leading to diarrhea and minor stomach issues, such as bloating, nausea, flatulence and lack of appetite. People with a history of hormone-related cancers, including breast, uterine, and prostate cancer, should not take milk thistle. Neither should those allergic to ragweed, chrysanthemums, marigolds, chamomile, yarrow, or daisies.
Milk thistle may interfere with the following medications, because both milk thistle and these medications are broken down by the same liver enzymes:
- Allergy drugs -- Such as fexofenadine (Allegra)
- Drugs for high cholesterol -- Including statins such as lovastatin (Mevacor, Altocor)
- Anti-anxiety drugs -- Including alprazolam (Xanax), diazepam (Valium), and lorazepam (Ativan)
- Antiplatelet and anticoagulant drugs (blood thinners) -- Including clopidogrel (Plavix) and warfarin (Coumadin)
- Some cancer drugs
- Drugs broken down by the liver
- Antipsychotics -- Includes butyrophenones (such as haloperidol) and phenothiazines (such as chlorpromazine, fluphenazine, and promethazine)
- Phenytoin(Dilantin) -- A medication used for seizures
- Halothane -- A medication used during general anesthesia
- Birth control pills or hormone replacement therapy