Safely Combining Prescription Drugs with Herbal Remedies

By Sheryl Sanchez, L.Ac.

Consumers buying herbal remedies are increasingly concerned about how these herbs may interact with pharmaceutical or prescription drugs that they are also taking. We tend to take more prescription drugs as we age, and the American populace is also continually increasing its use of complementary and alternative medicine (CAM), especially buying over-the-counter herbal preparations.

When I refer to herbs, I mean any Western or Chinese herbal remedy, singly or in combination, and vitamin supplements, including amino acids, minerals, glandulars, etc. (This does not include homeopathic remedies, because they are very safe to use, even when used in combination with drugs). And drugs refers to any pharmaceutical medication, whether you buy it over the counter or via prescription.

With the broad selection of herbs available, from traditional Western to Chinese to Amazonian to Ayurvedic, the process of buying herbal and vitamin supplements may often be a research project in itself! Therefore, if one is taking several prescription drugs and/or has serious medical conditions, it may be a wiser choice to seek out the knowledge of a professional trained in both herbology and pharmacology, and specifically, in herb/drug interactions

Understanding What Interactions Really Are

What are the real issues about herb/drug interactions? First, an interaction is a change in the pharmacological or therapeutic action of a drug when a herb is also taken. This change can either be an exaggeration of the drug’s effects or a reduction in its efficacy. Interactions can occur when taking a herb with a drug and can cause changes in absorption, distribution, metabolism, and elimination. Absorption occurs primarily in the intestines, and changes in how a drug or herb is absorbed can occur in several ways: A drug may cause binding in the gastrointestinal (GI) tract, which means that a drug’s molecules can combine with those of a herb and create a condition in which neither substance can be absorbed; herb absorption can be affected by a change of pH in the stomach due to consumption of antacids; and laxatives or drugs that bind the stool can affect GI motility or peristalsis, resulting in decreased or increased absorption.

Distribution refers to how the herb or drug is distributed to the various parts of the body. The only real known concern here is with anticoagulant drugs or blood-thinners such as Coumadin. The breakdown or metabolism of drugs or herbs occurs in the liver. A herb or drug may either inhibit or increase liver enzymes, with the result being a decreased or increased therapeutic effect, respectively.

A few drugs are known to inhibit liver enzymes, such as alcohol and certain anti-candida drugs. A few herbs, and notably grapefruit juice, are known to increase the effect of certain drugs (this effect is also known to occur slowly, in the timeframe of a few weeks). Elimination is a kidney function, so the main concern here is with patients who have kidney damage, because they will have a slower rate of elimination. Therefore, it is important for a practitioner to know what drugs a patient is taking; if any might cause kidney damage, lower dosages of herbs are used to prevent unwanted side effects. Interactions also occur if there is either a synergistic or an antagonistic reaction between herb and drug molecules. The synergistic ability of herbs is actually used for advantageous clinical outcomes in Chinese herbalism; in other words, two herbs are often combined to create a stronger medicinal effect. Interactions of this type primarily occur with anticoagulant, diuretic, and antidiabetic drugs.

Therefore, herbs that have these same properties blood-thinners and those that promote urination or lower blood glucose levels must be used under the supervision of a qualified health-care professional. A quick aside: I recommend that patients always take their herbs (and vitamins too, remember!) at a different time from their pharmaceuticals, with at least an hour (if not two) in between so that digestion and absorption can occur separately. Now that you have a clearer understanding of the real concerns in combining herbs with drugs, let me allay your fears by noting that most herb/drug interactions are actually minimally or not clinically significant(1). This means that most of the interactions that occur cause little or no potential harm to the patient because the interactions are infrequent and cause few or no adverse effects.

In summary, if patients know that they have any liver or kidney damage, or if they are regularly taking antacids or anti-candida, antidiabetic, or anticoagulant drugs, the best advice is to see a health-care professional who is trained in pharmacology and herbal medicine, and specifically, in herb and drug interactions. (1) Bob Flaws, Herb Toxicity and Drug-Herb Interactions with Chinese Medicine. Heavenly Herbs and Acupuncture Sheryl Murata, L.Ac. 530-877-7003 This should not be considered a substitute for medical advice. Consult your physician before making any health decisions.