From The Summer 2004 Issue of Natural Grocery Buyer

Herbs and Drugs: Friends or Foes?

Mitchell Clute

With the mainstream media’s coverage of herbal products bordering on the hysterical, retailers may find themselves entertaining many questions from shoppers concerned about possible interactions between supplements and prescription medications. In most cases, there is little risk involved in herb/drug interactions, but it’s important to be able to provide clear, accurate and appropriate information to consumers—especially older shoppers who may be more likely to be taking one or more long-term prescriptions.

“Theoretically, herb contraindications and drug interactions are not a serious problem,” says Don Summerfield, vice president of integrative medicine for Boulder, Colo.-based Pharmaca Integrative Pharmacy. “There is a much bigger problem with drug/drug interactions or drug/OTC interactions. But as more shoppers include dietary supplements in their health regimes, responsible retailers need to make their staffs aware of these interaction possibilities.”

Herb contraindications are another issue for retailers to be aware of. “In general, women who are pregnant or breast-feeding should stay away from most herbal medicines,” Summerfield says. The exceptions are a handful of herbs with mild action, such as chamomile or red raspberry leaf, which can be used for relaxation.

“There are very few known and proven herb/drug interactions,” says Rob McCaleb, president of Herb Research Foundation, also based in Boulder. “Almost all of it is theoretical.” However, there are a few interactions that are either well-documented or particularly dangerous, and retailers should be aware of these when they help customers make shopping decisions.

“I see the most concern related to interaction between certain herbs and blood-thinning medications, especially warfarin,” says Michael McGuffin, president of the American Herbal Products Association, based in Silver Spring, Md. Garlic, ginkgo, willow bark, vitamin E and a number of other herbal products and supplements have potential blood-thinning action; the concern is that if these herbs potentiate the prescription medication, the result could be internal bleeding. “However,” McGuffin says, “anyone on warfarin is under close medical supervision, and should be.” In fact, this interaction and many others have a positive side. Because herbs are almost always safer than prescription drugs, it’s possible that supplementing with a blood-thinning herb, such as ginkgo, could allow a consumer to take a smaller dosage of a medication such as warfarin. Of course, this is a matter that consumers must discuss with a physician or pharmacist.

St. John’s wort is one herb that has well-researched interactions with several drugs, and potential interactions with many more. St. John’s wort induces a particular enzyme system in the liver, which speeds up the metabolism of the many drugs that enter the body through this particular enzyme system. Two drugs known to be affected are the transplant anti-rejection drug cyclosporin and the anti-AIDS drug indinavir. “Consequently, the dose of the drug in the patient’s system will be lower than needed or intended,” says Mark Blumenthal, executive director of the American Botanical Council, based in Austin, Texas. “The bottom line is, people shouldn’t take St. John’s wort with any conventional drug until talking to a physician or pharmacist.”

But even in the case of St. John’s wort, there is a positive aspect to this information. “When you look at this interaction, you see that St. John’s wort is actually enhancing the body’s ability to detoxify, in the case of endinovir, or strengthening the body’s immune response, in the case of cyclosporin,” says McCaleb. “This is not a negative, even though it may have a negative effect on these particular drugs.”

Though some interactions are negative, others are positive. “Some supplements actually enhance the effectiveness or reduce the toxicity of certain drugs,” Summerfield says. For example, the best-selling drug in America is Lipitor, a statin drug used to control cholesterol. However, statin drugs can make the body’s store of the enzyme Co-Q10 unavailable, which in turn can lead to heart problems, including heart attacks. “This is a drug/nutrient depletion issue, and supplementing with Co-Q10 is a very positive preventive treatment for people taking statin drugs,” Summerfield says. It’s also important for consumers to avoid taking herbs and supplements that, in effect, cancel each other out. “For example, you wouldn’t want to take a stimulant herb and a sedative herb at the same time, or an herb which raises blood pressure and another that lowers it,” McCaleb says. Another issue is any supplement that might interfere with the absorption of a prescription medication. Psyllium, a bulking agent, is one such supplement. “Stimulant laxatives can also have a negative effect,” McCaleb says, “because they may hurry things through the digestive system faster than normal, thus preventing the absorption of therapeutic amounts of the drug.”

Retailers may not be herbal experts, but they can and should point customers toward resources that will answer their questions and address any concerns they may have about combining prescription drugs with herbal products. “I’d suggest that any store that sells herbal products purchase a copy of the revised and expanded Herb Contraindications and Drug Interactions, 3rd Edition, by Francis J. Brinker, N.D., (Eclectic Medical Publications, 2001),” says Summerfield.

Retailers should also make use of the resources in their own store. “Customers should be referred back to their primary care physician or, if there is a pharmacy in the store, to the staff pharmacist,” Summerfield says. “The pharmacist can be a very important resource in terms of addressing these issues.”

The key for retailers is making sure that consumers get the information they need. “I think the best advice for retailers is to mention to customers that they should keep their primary care practitioner informed of what supplements they’re taking if they are on medications for a serious condition,” McCaleb says. “Retailers can help keep the hysteria at bay by keeping in mind that interactions between herbs and drugs are rare, rarely hazardous and almost never life-threatening.”