Herb-Drug Interactions

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Herb-Drug Interactions
July 2021 The possibility of drug interactions, direct toxicities, and contamination with active pharmaceutical agents are among the safety concerns about dietary and herbal supplements. Although there is a widespread public perception that herbs and botanical products in dietary supplements are safe, research has demonstrated that these products carry the same dangers as other pharmacologically active compounds. Interactions may occur between prescription drugs, over-the-counter drugs, dietary supplements, and even small molecules in food—making it a daunting challenge to identify all interactions that are of clinical concern. Concerns about herb-drug interactions are often not based on rigorous research. Most herb-drug interactions identified in current sources are hypothetical, inferred from animal studies, cellular assays, or based on other indirect means; however, attention to this issue is needed for drugs with a narrow therapeutic index, such as cancer chemotherapeutic agents, warfarin, and digoxin. To date, well-designed clinical studies evaluating herbal supplement–drug interactions are limited and sometimes inconclusive. This issue of the Digest provides information about several herbs and their potential interactions with other agents.Read more »What the Science Says: Herb-Drug InteractionsLearn what current research has to say about:

Black Cohosh GarlicGinkgo BilobaGinseng (Asian)GoldensealSt. John’s WortRead more »Additional ResourcesScientific LiteratureInformation for Your PatientsRead more »
Visit NCCIH’s website to read the full issue of this month’s Clinical Digest.


NCCIH Clinical Digest is a service of the National Center for Complementary and Integrative Health (NCCIH), National Institutes of Health (NIH), U.S. Department of Health and Human Services. NCCIH Clinical Digest, a monthly e-newsletter, offers evidence-based information on complementary and integrative health, including scientific literature searches, summaries of NCCIH-funded research, fact sheets for patients, and more. NCCIH is 1 of 27 institutes and centers at the NIH. The mission of NCCIH is to define, through rigorous scientific investigation, the usefulness and safety of complementary and alternative medicine interventions and their roles in improving health and health care. For additional information, call NCCIH’s Clearinghouse toll free at 1-888-644-6226, or visit the NCCIH website at nccih.nih.gov.