According to a literature review and survey of 132 Canadian pharmacists, 47 percent of pharmacists have encountered an adverse interaction between a natural health product and a drug.
Only two of them, however, reported the event to the Canadian authorities. On the other hand, 19 percent of pharmacists have reported adverse reactions involving prescription or non-prescription drugs. As a result of the lack of reports of adverse interactions between natural health products and drugs, the frequency of such interactions may be considerably underestimated.
The surveyed pharmacists estimated that only five percent of their patients even ask for counseling about health products such as vitamins, St. John’s wort, Echinacea, and garlic, probably because they see natural and herbal products as less risky than standard drugs.
Dr. Sunita Vohra, professor at the University of Alberta and director of Edmonton’s Complementary and Alternative Research and Education program, led the study. She advises making certain pharmacies into sentinel sites, which would actively ask about and then report every adverse interaction. In this way, events involving natural health product-drug combinations could be more accurately tracked.
Sources: EurekAlert; The Annals of Pharmacotherapy, July 2007