NEW YORK Herb-using individuals who are at risk of bleeding should be advised to use caution, despite uncertainty about the actual degree of risk that may be involved, Adrian Fugh-Berman, M.D., said at a meeting on botanical medicine sponsored by Columbia University and the University of Arizona.
"Actual, theoretical, and fanciful herbal adverse events and interactions infest the medical literature," said Dr. Fugh-Berman of Georgetown University, Washington.
Given the level of uncertainty, it is prudent to check international normalized ratio (INR) of anticoagulated patients 714 days after starting any herbal, dietary supplement, or weight-loss regimen. By the same token, all herbs and supplements should be discontinued 2 weeks before surgery, she said.
Many herbs contain coumarins, most of which are benign. Some inhibit platelet aggregation in vitro, but few have been associated with actual bleeding episodes.
In one study, a 10-g dose of ginger decreased platelet aggregation 4 hours later, and a case was reported in which a 76-year-old woman developed nosebleeds and showed changes in INR after eating dried ginger and drinking tea made from it for several weeks. But three clinical studies found that up to 4 g of fresh ginger daily had no effect on bleeding.
Garlic oil has been shown to decrease platelet aggregation for up to 6 hours, and two cases of excessive postsurgical bleeding have been reported in which patients had consumed garlic-laden meals the night before.
"Tell patients not to consume meals heavy in garlic within a few days of surgery," Dr. Fugh-Berman advised.
Ginkgolide B, a component of Ginkgo biloba, is a known platelet aggregation factor antagonist, and the herb, alone or with analgesics, has been associated with intracranial bleeding events.
Clinical studies, however, found that one standardized ginkgo preparation (EGb761) had no effect on hemostasis, coagulation, or fibrinolysis in healthy men, and another (Bio-Biloba) did not change INR in patients who had been stabilized on warfarin.