Some Common Herbal Supplements May Have Dangerous Interactions With Common Prescription Drugs, Review Study Suggests.
TIME (1/24, MacMillan) reports some “common herbal supplements, including green tea and Ginkgo biloba, can interact with prescription medications” in “dangerous or deadly” ways, “according to a new research review published in the British Journal of Clinical Pharmacology.” Researchers reviewed “49 case reports of adverse drug reactions, along with two observational studies,” and concluded that herb-drug interactions were “highly probable” in 8% of the reports, “probable” in 51%, possible in 37%, and doubtful in 4%.
In one case report, a patient who took statins complained of intense leg cramps and pain—a commonly reported side effect—after drinking three cups of green tea a day. The reaction was attributed to green tea’s effects on statin levels in the blood, the researchers wrote, although they say more research is needed to rule out other possible causes.
In another report, a patient died after having a seizure while swimming, even though he was regularly taking anticonvulsant drugs for his condition. His autopsy, however, showed decreased levels of those drugs in his blood, likely due to the way Ginkgo biloba supplements—which he’d also been taking regularly—had affected their metabolism.
Taking herbal supplements has also been associated with worsening depression symptoms in people taking antidepressants, the authors wrote in their paper, and with organ rejection in those who had received kidney, heart or liver transplants. For cancer patients, chemotherapy drugs have been shown to interact with herbal supplements including ginseng, echinacea and chokeberry juice.
The analysis also showed that patients taking warfarin, a blood thinner, reported “clinically significant interactions” after taking herbal medicines containing sage, flaxseed, St. John’s wort, cranberry, goji juice and chamomilla. These herbs may affect the metabolism of warfarin, the researchers hypothesize, which may reduce its anticoagulation abilities or cause bleeding episodes.
