Mixing herbal and prescription meds - Clinical Advisor

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At a glance Herbal preparations and dietary supplements can have a significant impact on health and wellness. All that is natural is not necessarily safe, especially when combined with other pharmaceutical-grade medications or nonprescription dietary supplements. In order to avoid overdosing on any one component, consumers should be taking only one multivitamin or multimineral supplement at a time and should be aware of the ingredients if they intend to supplement with any other vitamin or mineral product. Manufacturers do not need to register with the FDA or obtain FDA approval prior to marketing a product, and there is no requirement for reporting of adverse events.

Herbal preparations have been used by mankind for medicinal purposes for more than 60,000 years. Moreover, field biologists have observed that sick animals change their diet, ingesting small amounts of bitter herbs and plants that they would otherwise avoid, to help facilitate healing.¹ There is little question that herbal preparations and dietary supplements can have a significant impact on health and wellness. Beware, however.

All that is natural is not necessarily safe, especially when combined with other pharmaceutical-grade medications or nonprescription dietary supplements. This article will discuss the magnitude of supplement and herb use in the United States today, review the most commonly used herbs and supplements and their purposes, and identify the most common pharmaceuticals that pose significant risk for drug/herb interaction. 


Big business


The use of complementary alternative medicine, including nonprescription drugs and supplements, is a booming business in the United States today. An estimated $33.9 billion a year is spent by consumers on nonprescription herbal supplements, natural/organic foods, natural personal care products, functional foods and other complementary alternative medicine practices.

With about $17 billion of this money spent exclusively on dietary supplements and herbs, this is big business.² Such purchases account for roughly 11% of all health-care drug spending and equal about 33% of what is being spent on prescription medications.^3,4 According to its company profile, in 2011, General Nutrition Centers, Inc, (GNC) spent nearly $53 million on advertising the nonprescription supplements and other health and wellness products sold in its more than 7,500 stores.⁵

Consumers are being bombarded on television, in magazines and by direct mail with information encouraging them to use "natural products" to lose weight, control their cholesterol, give them more energy, improve their sexual health and fulfill many other claims. 


Tracking safety


Supplements and herbal preparations fall under the jurisdiction of the Food and Drug Administration (FDA) via the Dietary Supplement Health and Education Act of 1994 (an amendment to the Food, Drug and Cosmetic Act).⁶ Requirements in the 1994 act specify that a product must be safe and that advertising claims must be truthful. Unfortunately, the act falls short of a few provisions that would provide additional protection for consumers.

Currently, manufacturers do not need to register with the FDA or obtain FDA approval prior to marketing a product, and there is no requirement for reporting of adverse events. Any claims against herb and supplement manufacturers are handled primarily through the Federal Trade Commission, including claims of false or misleading advertising and complaints of adverse medical events. 


Effects of commonly used supplements


Approximately 20% of the U.S. population admits to taking at least one supplement or herbal preparation daily, and more than 50% of the population admits to having used a natural preparation for medicinal purposes in the past 30 days.⁷ Therefore, understanding the purpose of the most commonly used substances and potential interactions with other supplements and prescription medications is critically important for health-care practitioners.

What exactly are we talking about? The discussion in this article will focus on any substance intended to be taken by mouth for the purpose of supplementing the diet and containing one of more of the following substances: vitamins, minerals, herbs, botanicals, amino acids or natural products, and/or labeled as a dietary supplement. Table 1 lists the most commonly used vitamins, herbs and supplements.


Multivitamins and multiminerals. The most widely used of all the dietary supplements by far, multivitamins and multiminerals come in the greatest number of varieties. From children's vitamins to preparations for the senior citizen, a vitamin and/or mineral supplement can be found for almost every health and wellness situation. The intended purpose is to provide added vitamins and minerals to one's diet and to supplement nutrition.

To avoid overdosing on any one component, consumers should be taking only one multivitamin or multimineral supplement at a time and should be aware of the ingredients if they intend to supplement with any other vitamin or mineral product. These products should not be taken with milk and or at the same time as an antacid.⁸ Furthermore, to avoid a dangerous elevation of potassium, patients taking multiminerals should not use salt substitutes, as most salt substitutes are made with potassium chloride.