Herbal Supplements May Cause Dangerous Drug Interactions

Alhough complementary and alternative medical treatments such as herbal
supplements are growing in popularity, a review article published in the
Journal of the American Academy of Orthopaedic Surgeons notes a
number of these products can have serious, potentially harmful side effects
when combined with medications prescribed during surgery and postoperatively.

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According to the review, around 20% of prescription users also take an
herbal supplement — with rates climbing as high as anywhere from 35% to
70% among orthopedic patients who are candidates for surgery.

“Herbal remedies are classified as dietary supplements, meaning
they are exempt from the safety and efficacy regulations that the Food and Drug
Administration requires for prescription and over-the-counter
medications,” review author

David T. Rispler, MD, stated in an press release. “As a result,
individual herbal remedies have not been thoroughly evaluated in large clinical
trials, and little information is available on the interactions between drugs
and herbs.”

Noteworthy interactions

The review noted that many of the most popular herbal supplements in use
today can result in serious side effects when used in conjunction with
prescription medications. Feverfew, ginger, cranberry, St. John’s Wort and
ginseng, for example, reportedly interact with warfarin. Other examples cited
in the release include:

  • Feverfew, ginger and gingko, which can interact with aspirin;
  • Valerian, which can intensify anesthetics;
  • St. John’s Wort, which can reportedly interact with
    immunosuppressive drugs and potentially lead to transplant rejection;
  • Glucosamine, chondroitin and flavocoxid, which can affect clotting
  • Black cohosh, which can interact with tamoxifen; and
  • Cat’s claw, which can interact with clotting agents.

The review also cautioned that many herbal products can pose additional
danger due to being marketed as “natural” or “homeopathic,”
resulting in patients assuming there is no danger of interaction.

Communication is key

Rispler noted physicians rarely ask patients about alternative medical
products during intake interviews — and thus these patients may continue
using the products because they perceive no risks.

“One of the main reasons that patients do not disclose the use of a
[complementary and alternative medical (CAM)] product is that they may not
believe it is important information to convey to the physician because they
feel they are safe to use and all-natural,” he stated. “Patients may
also decide not to report CAM product use if they are worried their physician
may be prejudiced against the supplement’s use, or believe their physician
will not have an understanding of the supplement.”

According to the release, most surgery-related side effects can be
avoided by ceasing use of the CAM product at least 1 week to 2 weeks
preoperatively and during the postoperative period while prescription
medications are being administered. The problem, Rispler stated, arises when
physicians do not know a patient is using a CAM product — thus,
communication with the patient about the use of CAM products should be taken
into account.

For more information:

  • Rispler DT, Sara J. The impact of complementary and alternative
    treatment modalities on the care of orthopaedic patients. J Am Acad
    Orthop Surg
    . 2011;19(10):634-643.

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