St. John’s Wort May Cause Dangerous Drug Interactions Interview with:
Scott A. Davis, MA
Research Administrative Coordinator
Department of Dermatology
Wake Forest School of Medicine

MedicalResearch: What are the main findings of the study?

Answer: St. John’s wort (SJW), a common complementary and alternative medicine (CAM) treatment for depression, is frequently used together with drugs that may interact dangerously with it. In data from the 1993-2010 National Ambulatory Medical Care Survey, a nationally representative survey of physician visits from the National Center for Health Statistics, SJW was prescribed together with drugs such as selective serotonin reuptake inhibitors (SSRIs), benzodiazepines, warfarin, statins, digoxin, verapamil, and oral contraceptives. Using SJW together with other antidepressants may cause serotonin syndrome, a potentially fatal condition.

MedicalResearch: Were any of the findings unexpected?

Answer: Yes, in 28% of St. John’s wort visits, we observed prescription of drugs that may have a dangerous interaction. This is a disturbingly high rate of co-prescribing these combinations of drugs, exposing patients to considerable risk of serious consequences they are probably not aware of.

MedicalResearch: What should clinicians and patients take away from your report?

Answer: Clinicians should be aware that St. John’s wort is a very common, popular treatment that many patients like to use, but it also has significant interactions with many drugs. They should not assume that because it is “all natural”, it is necessarily completely safe. Many patients are on multiple other drugs and may have unexpected reactions, such as failure of their antihypertensive treatments or contraceptives, when St. John’s wort is added.

Patients should be very careful to inform their doctor fully of all medications and supplements they are taking, such as SJW, and should be sure they know all potential risks of drug interactions before starting a new medication.

MedicalResearch: What recommendations do you have for future research as a result of this study?

Answer: Future research should define more precisely the risks associated with drug interactions involving St. John’s wort, especially interactions with other antidepressants. Research should also seek to inform physicians and patients more fully about how to avoid unsafe interactions when using complementary and alternative medicine treatments like St. John’s wort.


Use of St. John’s Wort in Potentially Dangerous Combinations
DavisScott A., FeldmanSteven R., and TaylorSarah L.. The Journal of Alternative and Complementary Medicine. -Not available-, ahead of print. doi:10.1089/acm.2013.0216.

Last Updated on July 2, 2014 by Marie Benz MD FAAD