Dietary supplements use remains prevalent in a variety of patient populations including elderly, prescription medication users, and those with chronic health conditions. A dietary supplement is intended to supplement the nutritional diet and contains one or more dietary ingredients such as vitamins, minerals, herbs or other botanicals.
St. John's wort (SJW) has been used in alternative medicine as a likely effective aid in treating mild to moderate depression, anxiety, insomnia and menopausal symptoms. According to one of the studies published in The Journal of Alternative and Complementary Medicine, “Use of St. John’s Wort in Potentially Dangerous Combinations”, by A. Davis, many serious drug interactions can occur when certain medicines are used at the same time especially in elderly population and patients with renal and cardiovascular problems. Some of the medications that were analyzed in this study that could have potentially dangerous interaction with SJW were selective serotonin reuptake inhibitors, benzodiazepines, warfarin, statins, verapamil, digoxin, and oral contraceptives.
According to supplement-drug interaction checker, Coumadin and SLW if taken together can cause serious interaction. SJW will decrease the level or effect of coumadin by altering the drug machinist.
References
Davis, S. A., Feldman, S. R., & Taylor, S. L. (2014). Use of St. Johns Wort in Potentially Dangerous Combinations. The Journal of Alternative and Complementary Medicine,20(7), 578-579. doi:10.1089/acm.2013.0216