How Drugs and Herbs Interact

How Drugs and Herbs Interact


Medications and supplements are a common part of many people’s lives. According to the CDC about half the population is on at least one prescription medication. Another survey from the CDC reported an estimated 62% of American use some form of alternative medicine, including supplements, specialized diets and natural medicine practitioners. With many people on prescription medications and/or self medicating with supplements and medical diets, an area of important concern in healthcare is the interactions of medications and supplements. Though an estimated hundred million Americans take herbal supplements, only eighteen percent mention these supplements to their doctors. There are many ways in which supplements and medications can interact with each other and being aware of the complexity and strength of these interactions can reduce risk of toxicity or rendering a medication or supplement less effective.



Many medications require nutrients to be completely effective or otherwise are made stronger when supported with nutrients. For example, some drugs used to support bone density require an adequate intake of calcium. The supplements and medications do not have the same specific action, but work together with the same goal in mind. Adequate supplementation of supporting nutrients may enhance the function of some medications or herbs.



Everything the body consumes requires nutrients to process it, to make it active as well as to aid in clearing it from the body. These requirements for medications and botanicals, as well as specific nutrients are known by physicians and should be accounted for when considering the nutritional needs of each individual. Taking supplements or medications can create deficiencies which may cause side effects as well as potentially making other medicines less effective.



Many medications were first discovered from plant and herb sources. Red yeast rice and white willow bark are two examples of natural substances that were used to create what are now pharmaceuticals such as statin drugs and aspirin. Because they work on the same pathways with the same actions, taking supplements or medications with the same mechanism of action can increase the response and can become toxic.



Some substances may work on the same receptors and pathways, but instead of supporting each other, they are competing. This competition often renders one or both substances less effective.



The liver, kidneys and colon are responsible for the removal of medications and supplements from the body. The liver utilizes two phases, appropriately named phases one and two, to package up substances to be removed from the body. These phases are a set of enzymes and biochemical pathways that can be dramatically affected by many substances. Certain medications and supplements, such as St. John’s Wort, speed up these pathways, increasing the clearance and decreasing the effectiveness of other medicines. Other herbs and even foods, such as grapefruit, slow down these pathways and keep some drugs and supplements in the body longer, posing a risk of toxicity. The kidney and colon’s ability to clear substances can also be altered. The length that a supplement or medication can stay in the body can vary substantially when other substances are taken along with it.



Anything we consume must compete to assimilate and absorb into our bodies. Foods, supplements and medications alike need to pass through the digestive tract to have their effect on the body. Many times these can inhibit each other and therefore the dose ingested is not the dose absorbed. For example, soy as well as black tea can inhibit the absorption of iron. Understanding how to effectively take supplements and medications will ensure they are assimilated into the body properly.


Everyday researchers are finding new medications, natural substances and foods that can promote wellness, however, appreciating their interactions will allow them to work optimally and affect their goal, improving health.


Dr. Lauren Young is a board certified naturopathic physician with a family practice in Manchester, CT. She is currently accepting new patients and is in network with most insurance companies. To make an appointment, call (860)533-0179 or visit

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