Question: St. John's Wort Drug Interactions
I've heard that St. John's Wort can interact with certain prescription drugs. What can you tell me about this?
Answer: On February 10th, 2000 the FDA issued a Public Health Advisory (link no longer available) for certain drugs that may potentially interact with St. John's Wort. A study at The National Institutes of Health (NIH) showed a significant drug interaction between St John's wort and Indinavir, a protease inhibitor used to treat HIV infection. Concomitant administration of St. John’s Wort and Indinavir substantially decreased Indinavir plasma concentrations. Based on this study and reports in the medical literature, St. John's Wort appears to be an inducer of an important metabolic pathway, cytochrome P450. As many prescription drugs used to treat heart disease, depression, seizures, certain cancers or to prevent conditions such as transplant rejection or pregnancy (oral contraceptives) are metabolized via this pathway, the FDA recommended that health care providers should alert their patients that St. John's Wort use might reduce the effectiveness of their medications. If you are taking any prescription medications, consult with your doctor before using St. John's Wort.
