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Although use of many dietary supplements has leveled off or decreased in the last few years (with a few notable exceptions, such as vitamin D and fish oil), many patients are still interested in trying supplements, either in place of (alternative) or along with (complementary) prescription and OTC therapies. Patients have increased desire for knowledge on the potential benefits and risks of these therapies and are more often expecting pharmacists and other healthcare providers to provide information they can use to make decisions.

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 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 section “Clinical Course” 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?

    • This might be a silly question for prescription medications, but many supplements are used with only a small amount of knowledge regarding 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 reasonable information or instructions. For example, if a plant extract has been shown to improve glucose uptake in tissue studies, then 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 will have to ...

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