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Interactions

Interactions with Drugs

Animal studies suggest that milk thistle may interfere with the way the body processes certain drugs using the liver's "cytochrome P450" enzyme system. As a result, the levels of these drugs may be increased in the blood, and may cause increased effects or adverse reactions. Many types of drugs may be affected. Individuals should speak with a qualified health care provider to obtain a list of these drugs and their possible interactions. In theory, milk thistle may lower blood sugar levels. Caution is advised when using medications that may also lower blood sugar. Patients taking drugs for diabetes by mouth or insulin should be monitored closely by a qualified healthcare provider. Medication adjustments may be necessary.

A possible interaction with phenytoin (Dilantin®) has been reported with milk thistle. However, the facts are unclear.

Milk thistle ingredients have been reported to prevent amiodarone toxicity in animal studies. Based on laboratory and animal study, milk thistle may increase the effects chemotherapy drugs like doxorubicin, cisplatin and carboplatin. Milk thistle may interact with hormonal agents, alcohol, antiretroviral drugs or indinivir.

Interactions with Herbs and Dietary Supplements

Animal studies suggest that milk thistle may interfere with the way the body processes certain herbs or supplements using the liver's "cytochrome P450" enzyme system. As a result, the levels of other herbs or supplements to be too high in the blood. It may also alter the effects that other herbs or supplements have on the P450 system.

Milk thistle may lower blood sugar levels. Caution is advised when using herbs or supplements that may also lower blood sugar. Blood glucose levels may require monitoring, and doses may need adjustment.

Milk thistle may interact with hormonal agents. Silymarin and vitamin E have been reported to prevent amiodarone toxicity in animal studies. Milk thistle may chelate iron and slow calcium metabolism.

Milk thistle may also interact with antiretroviral herbs.

Attribution

This information is based on a professional level monograph edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com): E-P Barrette, MD (Case Western Reserve University School of Medicine); Ethan Basch, MD (Memorial Sloan-Kettering Cancer Center); Samuel Basch, MD (Mt. Sinai Medical Center, NY); Heather Boon, B.Sc.Phm, PhD (University of Toronto); Ivo Foppa, MD, ScD (Harvard School of Public Health); Paul Hammerness, MD (Harvard Medical School); David Sollars, MAc, HMC (New England School of Acupuncture); Philippe Szapary, MD (University of Pennsylvania); Catherine Ulbricht, PharmD (Massachusetts General Hospital); Wendy Weissner, BA (Natural Standard Research Collaboration); Meng Yeng, PharmD (ACS-Consultec).