Milk Thistle

Are there any interactions with medications?

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Medications changed by the liver (Cytochrome P450 2C9 (CYP2C9) substrates)
Interaction Rating: Moderate Be cautious with this combination.
Talk with 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 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.

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Medications changed by the liver (Cytochrome P450 3A4 (CYP3A4) substrates)
Interaction Rating: Moderate Be cautious with this combination.
Talk with 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 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.

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Medications changed by the liver (Glucuronidated drugs)
Interaction Rating: Moderate Be cautious with this combination.
Talk with 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 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.

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Tamoxifen (Nolvadex)
Interaction Rating: Moderate Be cautious with this combination.
Talk with your health provider.

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.

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Estrogens
Interaction Rating: Minor Be cautious with this combination.
Talk with your health provider.

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.

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Medications used for lowering cholesterol (Statins)
Interaction Rating: Minor Be cautious with this combination.
Talk with your health provider.

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).

Dosing considerations for Milk Thistle.

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.