The growing incidence of drug-supplement interactions

The combined use of supplements with prescription and non-prescription drugs is increasing along with the potential for significant interactions.

Here’s the evidence.

Researchers from the University of Washington in Seattle and Boise State University in Idaho reviewed the prevalence of CAM product use with conventional medications in 5052 elderly people receiving Medicare.

And, the results.

  • The years covered included 1994, 1995, 1997, and 1999.
  • The percent using CAM products increased from 6%, to 7%, 13%, and 15% during that time.
  • The percent using CAM products plus conventional drugs was 6%, to 6%, 12%, and 14%.
  • Among those taking CAM products plus conventional drugs, 6% took combinations with a significant risk for an adverse interaction.
  • Most of these cases involved a risk of bleeding due to the use of ginkgo, garlic, or ginseng together with aspirin, warfarin (Coumadin: blood thinner), ticlopidine (Ticlid: to reduce the risk of stroke), or pentoxifylline (Trental: to treat intermittent claudication).
  • Even more took combinations of theoretical or uncertain risk for an adverse interaction.

The bottom line?
I love this quote: In 1993, Senator Orrin Hatch said, “most of these [herbal remedies] have been on the market for 4,000 years, and the real issue is risk. And there is not much risk in any of these products.”

The consequences — good and bad — of this belief and subsequent legislation that resulted in the Dietary Supplement Health and Education Act (DSHEA) have been far reaching. However, when combined with the American Association of Poison Control Centers’ report on the risks of supplements, we should recognize that supplements are, in fact, drugs to be used carefully.

9/26/07 17:36 JR

Hi, I’m JR

John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at, a complementary and alternative medicine website.