Detractors of herbal medicine use have legitimate con-cerns about dosage variability, possible toxicity and adulteration, herb–drug interactions, and above all, lack of FDA regulation. Far from being intrinsically harm-less, many pharmacologically active plant alkaloids and other compounds are natural defensive poisons; their very effectiveness may be an unanticipated conse-quence of their adaptive toxicity to grazing animals and
insects. Thus, herbal products like digitalis, while quite “natural,” may also be dangerous or even fatal in over-dose. Other herbs may not be superior to better-researched pharmaceuticals, or they may delay the use of more effective therapy. While herbal research has un-derstandably lagged far behind that of patented med-ications, a surprising number of clinical trials exist, al-though some of them are fraught with methodological problems and much of the data is foreign and therefore not readily accessible to U. S. physicians. There is also the frustrating problem of interpreting conflicting re-search results; it is possible to assemble impressive arrays of studies both supporting and questioning the effectiveness of a particular herbal product. These con-flicting findings may result from flawed study design, the use of differing preparations, or different study end points. Unfortunately, despite the recent increase in herb research, significant gaps in knowledge remain. An additional concern is that few if any available studies have been conducted on pregnant women or children.
Some herbal preparations, particularly some un-branded Asian imports, have been found to contain in-active fillers or adulterants. In one assessment, 24% of imported herbs were found to contain ingredients not on the label. These included specific medications (as-pirin, caffeine, diuretics, and even benzodiazepines), not to mention heavy metals, such as lead. Some Asian for-mulations may also contain animal components. Therefore, it is advisable to buy only products that list the following information: botanical name or names, parts used, expiration date, batch or lot number, and the manufacturer’s name and address.
Of special concern today are the possible herb–drug interactions with which patients and their health care providers must be familiar. Some herbs, such as ginkgo, garlic, ginger, chamomile, horse chestnut, and feverfew, can prolong bleeding time and should be avoided with coumadin and antiplatelet regimens. It is also necessary that they be stopped 2 weeks prior to surgery. Other herbs, including kava, St. John’s wort, and valerian, also must be discontinued prior to surgery because they can unpredictably alter the effects of common anesthetics. Panax ginseng may cause blood pressure fluctuations, and some herbs, notably St. John’s wort, may lower the blood levels of many coadministered medications. For this reason, it is critical for consumers and their health care providers to maintain an open dialogue about herb use; the use of over-the-counter herbs and supplements should be inquired about when obtaining a medical his-tory. Patients are frequently reluctant to discuss their herb use either because they fear disapproval or be-cause of the all too often correct perception that the provider is not knowledgeable enough to warrant giving the information. Blanket condemnation of herb use of-ten has the counterproductive effect of terminating any further communication between physician and patient.
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