What Do I Need to Know About Dietary and Herbal Supplements and My Medications?

By Sarah Leslie, Phar.D., New Ulm Medical Center


More than 50 percent of American adults report using at least one dietary supplement on a daily basis at an annual cost of  more than $27 billion. But how safe and effective are these supplements?


The FDA regulates prescription and over-the-counter (OTC) drugs. To be sold, drugs must be safe and effective. Here are some other lesser-known facts about safety and effectiveness:

  • Makers of dietary supplements are not required to prove efficacy, safety or quality before marketing their product.    
  • The manufacturer of the supplement, not the FDA, is responsible for determining that its products are safe and produced under proper sanitary conditions.   
  • There is no law requiring a supplement manufacturer to share information about the safety or benefits of their products.
  • Labels of supplements are required to state: "This product is not intended to diagnose, treat, cure or prevent any disease."
  • Herbal and dietary supplements can vary widely in the amount of active ingredient. The plant species used (e.g., Echinacea purpurea vs. Echinacea pallida) and the part of the plant that is used (e.g., leaves vs. fruit) have different amounts of active ingredient.   
  • Harvesting, storing and processing may also affect the potency of a supplement. This makes it difficult for consumers to know exactly what dose is contained in a particular supplement.

Why is all this important?


  • Some drugs such as warfarin (Coumadin) interact with many dietary and herbal supplements.
  • Some supplements such as ginger, ginseng, blue cohosh and licorice may worsen high blood pressure.
  • Certain supplements may raise or lower blood glucose, which can be harmful in patients with diabetes as well as interact with prescription medications to treat diabetes.       
  • Many supplements need to be stopped prior to surgery as they can interfere with the body's ability to stop bleeding.
  • Other supplements may be toxic to the liver or kidneys, especially if used with other substances that have effects on these organs.
  • Children and the elderly may be especially sensitive to the effects of supplements.


Talk to your health care provider before starting any supplement


All medicines have risks, including dietary and herbal supplements. Just because something is natural doesn't mean it is safe. Before starting any supplement, ask your health care provider or pharmacist if the supplement is safe for you to use with your prescription or non-prescription medications or if the supplement can aggravate any medical conditions you may have.


Bring your supplement bottles to all medical appointments for your health care provider to review and discuss. Look for supplements with the USP Verified Mark indicating that the product contains the ingredients and dosage listed on the label, does not contain harmful contaminants and is manufactured under sanitary conditions.