Supplement: Herb-Drug Interactions: How to Identify a Problem and What to Do
The Food and Drug Administration (FDA), as well as health care professionals and organizations, receives many inquiries each year from consumers seeking health-related information, especially about herbal supplements. Clearly, people choosing to supplement their diets (with herbals, vitamins, minerals, or other substances) want to know more about the products they choose so that they can make informed decisions about them. The choice to use an herb can be a wise decision that provides health benefits. However, under certain circumstances, these products may be unnecessary for good health or they may even create unexpected risks.
Assessing the clinical data
Given the abundance and conflicting nature of information now available about herbal supplements, you may need help to sort the reliable information from the questionable. In 2001, Fugh-Berman and Ernst reviewed the medical literature for herb-drug interactions, identifying 108 suspected cases of herb-drug interactions (see Table 1 below).
| Table 1 |
| Herb-drug interaction data |
|
• 108 cases
of suspected herb-drug interactions
Adapted from:
Fugh-Berman A, Ernst E. Herb-drug interactions: Review and assessment
of report reliability. Br J Clin Pharmacol 2001;52:587-595 |
These authors also developed a 10-point scale to evaluate the quality of a case report (see Table 2).
| Table 2 |
| 10-point scale for reliable reporting of an herb-drug interaction |
|
Criteria: A point is given for each of the following criteria:
Scale: 0-3 points: unevaluable—report contains insufficient information to determine the likelihood of an interaction 4-7 points: possible interaction—evidence points to an interaction, but other causes may be involved 8-10 points: likely interaction—report provides reliable evidence for an interaction Adapted from:
Fugh-Berman A, Ernst E. Herb-drug interactions: Review and assessment
of report reliability. Br J Clin Pharmacol 2001;52:587-595. |
When to suspect an herb-drug interaction
Surveys of patients with chronic conditions indicate their willingness to explore alternative therapies. Unfortunately, because they usually take medication to treat their conditions, these patients are at increased risk of an adverse effect when taking herbal remedies. Tables 3 and 4 list common signs of an herb-drug interaction and the circumstances in which a serious interaction can occur.
| Table 3 |
| When to suspect an herb-drug interaction |
|
| Table 4 |
| Circumstances in which a serious herb-drug interaction can occur |
|
Reporting adverse events
If you believe an adverse event is related to the use of any dietary supplement product, contact the FDA’s MedWatch program by phone (800) FDA-1088, fax (800) FDA-0178, or on-line: www.fda.gov/medwatch/how.htm.
Table 5 outlines several steps you should consider if you suspect an herb-drug interaction.
| Table 5 |
| What to do if you suspect an herb-drug interaction |
|
Source: Food and Drug Administration. Available at: www.cfsan.fda.gov/~dms/ds-savvy.html.
Herb-drug interactions: How to identify one and what to do. Altern Med Alert 2003;6(3 suppl):S1-S2.
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