Caution should be exercised in supplementing the diet with calcium when the patient is taking calcium channel blockers for hypertension or other cardiovascular disease. Additional medications that can potentially interact with calcium include aluminum-containing antacids, beta blockers, bile acid sequestrants, corticosteroids, estrogen supplements, some antibiotics, anticonvulsants, diuretics and thyroid supplements. The hypothesis that taking calcium supplements leads to development of gallstones or kidney stones is unsubstantiated. 

Interactions from another perspective

Just as clinicians should be aware of the possible effects of supplements their patients report using, they must also be aware of the potential for medications they prescribe to interact with vitamins, herbs and supplements. Table 2 provides a list of drugs with a high potential for drug/drug or drug/food interaction.

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Patients are using more and more nonprescription herbs, vitamins and supplements, and health-care providers are recognizing the contributions and benefit of using nonpharmaceutical supplementation in the treatment of certain illnesses and following injuries. These products can enhance or inhibit the potential effects of other substances patients are ingesting.

Many times, patients are reluctant to tell their clinician that they are using these OTC products. The patient may believe that the supplements are without risk, that the health-care provider may react negatively to use of nonprescription treatments or that the information is not important enough to share with their regular practitioner.

Whatever the reason, the likelihood is that your patient will use a vitamin, herb or dietary supplement of some sort to impact his or her health in the next year. As the health-care provider, you should be ready to question what products he or she is using and have a basic understanding of the effects these products can have — both beneficial and harmful.

You should also have a general understanding of dangerous combinations, side-effect profiles and the unregulated nature of supplement production. Having reference materials available to check unfamiliar products and to provide education to patients on the latest and greatest health-enhancement product is critical to maintaining optimum health status and preventing untoward drug/drug, drug/food and drug/supplement interactions. 

This article should not be construed as a complete or total list of potential vitamin, herb or supplement uses or interactions with other drugs, foods or supplements. It is simply an introduction to some common potential interactions and should serve as a resource to encourage providers to continue their education on this very important topic.

Lorraine W. Bock, MSN, CRNP, CEN, is Director of Legislative Health Services, Pennsylvania House of Representatives. She specializes in family medicine and is the owner of Bock CRNP Services in Harrisburg.


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