More threads by David Baxter PhD

David Baxter PhD

Late Founder
St. John's Wort

Derived from the aerial parts of the plant, St. John's wort generally is used for depression, seasonal affective disorder, and anxiety. Products currently are standardized based on hypericin content, although the hyperforin and bioflavonoid contents are also believed responsible for activity. St. John's wort is metabolized primarily by the liver.

Some studies comparing St. John's wort to standard antidepressants suggest that it may be as effective as imipramine or selective serotonin reuptake inhibitors (SSRIs) to treat mild to moderate depression. Results from another clinical trial indicate that the effectiveness of St. John's wort is comparable to paroxetine, an SSRI, in the treatment of moderate to severe depression and is well tolerated. But a meta-analysis shows that data are inconsistent. Studies also show possible efficacy in the management of anxiety and premenstrual syndrome, although additional research is necessary.

St. John's wort can interact with many medications owing to induction of cytochrome P-450 3A4 and other mechanisms. Significant interactions include decreased efficacy of antiretrovirals, cyclosporine, tacrolimus, antiepileptics, irinotecan, and other chemotherapeutic agents. Serotonin syndrome may occur when St. John's wort is combined with antidepressants, sympathomimetics, or triptans.

Frequently reported adverse events include nausea, headache, constipation, dizziness, confusion, fatigue, and dry mouth. St. John's wort should be used under medical supervision.

J Soc Integr Oncol. 2006 Winter;4(1):52-5.



Your best course would be to speak to your doctor, who should know all the medications you currently are prescribed, over the counter preparations such as cough meds, upset tummy meds and any other herbal preparations you use.

As is noted in David's posting by using St. John's Wort under medical supervision, you would receive the right guidance in your particular case.

For your own safety, it would not be adviseable to take the advice of a non medical person in this situation.


Thx Steve.. I will hold off on starting it until I talk to my Dr. I am not making a special trip, but next time I go.


FDA Source

February 10, 2000


Dear Health Care Professional:
The Food and Drug Administration would like to inform you about results from a study conducted by The National Institutes of Health (NIH) that showed a significant drug interaction between St John's wort (hypericum perforatum), an herbal product sold as a dietary supplement, and indinavir, a protease inhibitor used to treat HIV infection. In this study, concomitant administration of St. John?s wort and indinavir substantially decreased indinavir plasma concentrations, potentially due to induction of the cytochrome P450 metabolic pathway. For additional information on this study please refer to the February 12, 2000 Lancet publication (Piscitelli, et al).


Indinavir and other antiretroviral agents

At this time, pharmacokinetic data are available only for concomitant administration of indinavir with St. John?s wort. However, based on these results, it is expected that St John?s wort may significantly decrease blood concentrations of all of the currently marketed HIV protease inhibitors (PIs) and possibly other drugs (to varying degrees) that are similarly metabolized, including the nonnucleoside reverse transcriptase inhibitors (NNRTIs). Consequently, concomitant use of St John?s wort with PIs or NNRTIs is not recommended because this may result in suboptimal antiretroviral drug concentrations, leading to loss of virologic response and development of resistance or class cross-resistance.

Because herbal products are widely used in the United States and are available in various forms such as combination products and teas, it is important that health care professionals ask patients about concomitant use of products that could contain St. John?s wort (hypericum perforatum).

In addition, FDA is working closely with drug manufacturers to ensure that product labeling of antiretrovirals is revised to highlight the potential for drug interactions with St. John?s wort.

Other drugs

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 conditions such as heart disease, depression, seizures, certain cancers or to prevent conditions such as transplant rejection or pregnancy (oral contraceptives) are metabolized via this pathway, health care providers should alert patients about these potential drug interactions to prevent loss of therapeutic effect of any drug metabolized via the cytochrome P450 pathway.

All health care professionals are encouraged to report any serious adverse event associated with the concomitant use of prescription drugs and St. John?s wort products to the FDA?s MedWatch program at 1-800-FDA-1088 (fax 1-800-FDA-0178).

Sincerely yours,

Murray M. Lumpkin, M.D
Deputy Center Director (Review Management)
Center for Drug Evaluation and Research Susan Alpert, Ph.D., M.D.
Director of Food Safety
Center for Food Safety and Applied Nutrition
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