Herbal Remedies in the United States: Potential Adverse Interactions With Anticancer Agents
Interest in the use of herbal products has grown dramatically in the Western world. Recent estimates
suggest an overall prevalence for herbal preparation use of 13% to 63% among cancer patients. With
the narrow therapeutic range associated with most anticancer drugs, there is an increasing need for
understanding possible adverse drug interactions in medical oncology.
In this article, a literature overview is provided of known or suspected interactions of the 15 best-selling
herbs in the United States with conventional allopathic therapies for cancer.
Herbs with the potential to significantly modulate the activity of drug-metabolizing enzymes (notably
cytochrome P450 isozymes) and/or the drug transporter P-glycoprotein include garlic (Allium sativum),
ginkgo (Ginkgo biloba), echinacea (Echinacea purpurea), ginseng (Panax ginseng), St John’s wort
(Hypericum perforatum), and kava (Piper methysticum). All of these products participate in potential
pharmacokinetic interactions with anticancer drugs.
It is suggested that health care professionals and consumers should be aware of the potential for
adverse interactions with these herbs, question their patients on their use of them, especially among
patients whose disease is not responding to treatments as expected, and urge patients to avoid herbs
that could confound their cancer care.