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Herbal Supplements Can Interact with Drugs in Surgery Patients


If you are planning to undergo surgery, make sure you tell your doctor about any herbal supplements you are taking. Some of these products can interact with drugs taken during and after surgery and cause serious side effects, according to the authors of a new review from Michigan State University College of Human Medicine.

Herbal supplements are not always safe

A significant number of people who take herbal supplements also use prescription drugs—about 20% according to the new review, and among patients who are candidates for orthopedic surgery, the numbers may be as high as 35% to 70%. All of these individuals could be jeopardizing their health if they don’t tell their healthcare providers about their supplement use before undergoing surgery.

Yet some people believe if something is labeled “herbal” it must be completely safe. Although herbal supplements can be quite beneficial and often do not cause the side effects associated with conventional medications, they can have serious adverse effects when combined with medications.

David T. Rispler, MD, director of the Grand Rapids/Michigan State University Orthopedic Residency Program, noted that “individual herbal remedies have not been thoroughly evaluated in large clinical trials, and little information is available on the interactions between drugs and herbs.”

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Potentially dangerous events can be avoided if doctors know their patients are taking herbal supplements. Unfortunately, pre-surgery intake interviews do not always include questions about a patient’s use of alternative medicine. Some patients also don’t reveal they are taking these supplements because they are afraid their doctors will disapprove or don’t know enough about the products, or that the supplements are safe and therefore not important enough to mention.

But use of herbal supplements is well worth revealing. For example:

  • Black cohosh: can interact with tamoxifen (cancer drug)
  • Cat’s claw: can interact with blood thinners (e.g., warfarin), blood pressure medications, and cyclosporine (an immunosuppressive drug, helps prevent transplant rejection)
  • Cranberry: can interact with warfarin
  • Feverfew: can interact with warfarin
  • Garlic: can interfere with warfarin and cyclosporine
  • Ginger: can interact with aspirin and warfarin
  • Glucosamine and chondroitin: can affect blood thinners
  • St. John’s wort: can interact with warfarin and immunosuppressive drugs
  • Valerian: can increase the effects of anesthetics

Dr. Rispler noted that health/medical assessment forms should have questions concerning use of complementary medicine products so patients will be encouraged to reveal their use. In that way, their doctors can advise them to stop taking the supplements one to two weeks before surgery and during their recovery period and thus most surgery-related side effects can be avoided.

“By opening up a conversation on the use of herbal medications around the time of surgery and compiling a complete list of all prescribed and self-prescribed medications and supplements,” explained Dr. Rispler, “patients and physicians may be able to work together to decrease the risk of complications that can occur during and following surgery.”

Rispler DT, Sara J. Journal of the American Academy of Orthopaedic Surgeons 2011; 19(10): 634-43

Picture credit: Wikimedia Commons