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Although use of many dietary supplements has leveled off or decreased in the past few years, many patients are still interested in trying supplements, either in place of (alternative) or along with (complementary) prescription and OTC therapies. Patients have a continued desire for knowledge on the potential benefits and risks of these therapies, and often expect pharmacists and other healthcare providers to provide information they can use in determining what treatment option is preferred.

As part of providing appropriate care, clinicians have a duty to help individual patients avoid interactions with their drug therapies and prevent use of products unsafe for them because of other disease state contraindications. That is a fairly straightforward task when dealing with prescription and OTC therapies; there is so much information and research available that most problems and risks are well understood. If a patient is prescribed a contraindicated drug, we can ensure that he or she does not receive it. With dietary supplements, there is often not enough information available to make clear-cut judgments about risks. We also cannot prevent patients from taking supplements even if supplements are known to be unsafe or risky for them, because we do not control their access to those therapies. Instead, we are limited to providing as much guidance as possible to help maximize any possible benefit and minimize possible harm.


The following questions regarding supplement therapy aid in the decision-making process and will be addressed in the “Clinical Course” section of the Casebook. It is assumed that necessary information about a patient’s medical history and current drug regimen has already been obtained.

1. What is the known or proposed mechanism of action?

  • The pharmacology of FDA-approved prescription medications is generally understood, but many supplements are used with only limited knowledge about their pharmacologic activities. Botanical supplements, in particular, are extremely complex and may have multiple activities, some synergistic to the desired effect and some in opposition or unrelated. When there is little or no definitive human evidence for either efficacy or safety, we must often extrapolate based on in vitro or animal data in order to provide patients with information or instructions. For example, if a plant extract has been shown to improve glucose uptake in tissue studies, it is reasonable to expect that activity to some extent when taken by human beings. It would also be reasonable to offer cautions about use with sulfonylurea drugs or other hypoglycemic agents, even when no case studies or clinical trials have reported interactions. Depending on the risks if an interaction should happen, appropriate real-life statements to patients can range from: “If you use this supplement, you ...

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