Study Finds Low Risk of Dietary Supplement and Prescription Drug Interactions

The pharmaceutical industry has warned of drug/supplement interactions for many years. This concern has even been the basis of potential legislation to limit your access to dietary supplements. However, recently it has been found that these "interactions" occur less frequently than had been thought. In fact, it is only a handful of products that seem to have this issue.

Courtney Cavaliere of the American Botanical Council recently reported on a study published in the March edition of the American Journal of Medicine which found very little actual risk of harm from dietary supplement and prescription drug interactions.

According to Ms. Cavaliere, the authors of the study based their results on responses to an 85-question survey administered to 1818 patients from 6 specialty clinics of the Mayo Clinic from September 2002 through July 2003. Of the 1795 patients who responded to the survey, 710 (or 39.6%) reported that they used dietary supplements. Survey respondents provided medical records with information on their prescription medications, and respondents indicated in the survey whether they concurrently used dietary supplements by choosing from a list of 52 dietary supplements or entering the names of unlisted supplements. Prescription medications included physician-prescribed pharmaceuticals, as well as aspirin.

The authors of the study compiled a master list of potential medication interactions based upon potential herb-drug interactions noted in the various databases and textbooks. Based on the survey data, the authors identified 369 potential interactions among 236 patients, and 107 of these interactions were considered to have potential clinical significance.

Here are the 5 most commonly used dietary supplements with a potential for interaction: Garlic [Allium sativum], Valerian [Valeriana officinalis], Kava [Piper methysticum], Ginkgo [Ginkgo biloba], and St. John’s wort [Hypericum perforatum]. These five accounted for nearly 70% of all possible interactions.

The 4 most common prescription medication classes with a potential for interaction with supplements include: Antithrombotic medications, Sedatives, Antidepressants, and Antidiabetic agents. These classes of drugs accounted for 94% of all possible interactions. However, not one patient who participated in the survey experienced serious harm from a possible interaction during the study period, as determined by the patients’ medical records. “Serious harm” was defined as hospitalization for an aggravated underlying medical condition or for a new medical problem caused by an interaction.

According to the researchers, the study showed that only a small number of prescription medications and dietary supplements accounted for most potential herb-drug interactions. Moreover, the fact that no actual interactions were noted during the survey period demonstrated that the real potential for harm is quite low. The authors added that some interactions included in the study may have even been considered speculative.

Dave