Reported lack of interaction between ginseng or ginkgo biloba and other drugs

Research reported during the latest meeting of the American Society for Pharmacology and Experimental Therapeutics concludes that these herbals do not place people at risk for certain types of drug interactions.

Here are the details.

72 healthy adults were randomly assigned to one of 4 groups

  • Ginseng
  • Ginkgo biloba
  • Both herbs together
  • Placebo

First, they took a 5-drug combination without the herbals and again with the herbals. The 5-drugs were used as surrogates for a broader range of interaction risk.

The results show that “these herbal supplements do not alter how patients metabolize and clear drugs,” said Dr. Gregory Reed from Kansas Medical Center.

The bottom line?
My access to the results of this study is limited to a CNN article. Casual reading suggests that these herbals are perfectly safe, which they are not.

This type of study design does not guarantee that ginseng or ginkgo supplements at recommended doses will be devoid of additive or synergistic therapeutic effects with other drugs. It simply estimates the likelihood of a pharmacokinetic interaction (altered absorption, metabolism, excretion) with other drugs. Here is one they might have missed.

To his credit, Dr. Reed states, “We do not know if ginseng or ginkgo supplements at recommended doses can alter the effects of specific drugs in a patient.”

For more complete information on the use and safety of ginseng go here and here. More information on ginkgo biloba is here and here.

5/4/07 10:51 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.