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Many patients regularly use or occasionally try supplements, either along with prescription and over-the-counter (OTC) therapies, or in place of some therapies. Because pharmacists must educate and advise patients on drug therapies, it is essential to have a basic understanding of dietary supplements (DS) in order to assist in avoiding harm, whether from drug interactions, use of a contraindicated supplement, or a poor quality product. Pharmacists do not control access to these products, but can provide essential advice and recommendations.

Although some dispensing software systems include a few DS and check for interactions, there are thousands of botanical and nonbotanical DS. Every pharmacy should have one or more comprehensive resources available to be able to look up information when necessary. However, all pharmacists should be familiar with the most commonly used DS and those that present possible risks of greatest severity. Additionally, familiarity with the key points for investigating safety and making recommendations when encountering previously unknown supplements is essential.


The following questions assume that the pharmacist has fully gathered pertinent information about a patient’s medical history, current drug regimen, and reason for considering use of a DS.

  1. Does the supplement work?

    What clinical trial data are available to support effectiveness? When this is minimal, the type and severity of the patient’s disease state is a large factor in weighing risks and benefits, that is, what is risk of harm if the patient tries the supplement for a while and it is not effective? Risk is minimal with a self-limiting condition such as a cold but far greater for uncontrolled diabetes or hypertension. When the evidence to support effectiveness is stronger, it may be appropriate to use the supplement. For example, a trial period of 4 weeks in a patient with mild hypertension could be appropriate, but not with severe hypertension.

  2. Is the supplement safe?

    Often, this information is not well-understood because of a lack of long-term clinical trials, and therefore must be extrapolated from the mechanism of action, small animal studies, or case reports. Both in mass media and in medical literature, safety issues are sometimes underemphasized and sometimes overemphasized. The possible risks to the particular patient should be realistically balanced with the possible benefits.

    Patient education rule for all supplements: stop all use 10 to 14 days before any scheduled surgical procedures to avoid possible drug and anesthesia interactions or increased bleeding risks.

  3. How does the supplement work?

    This information is important for cautions and limitations in use. If well-researched, the mechanism of action may be available in general resources, but sometimes must be extrapolated from very limited in vitro or animal studies. For example, if animal studies have shown increased vasodilation, then it is reasonable to recommend caution, or to not use at all, when decreased blood pressure could be problematic, either due to a disease state ...

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