What issues should be kept in mind when dealing with drug interactions involving herbal products?
Most drug interactions involving herbal products are not well documented. Reviews of herbal drug interactions are published with increasing frequency. Some of these reviews are rigorous and well written, but many tend to place more credence in the interactions than is justified by the available data. For example, dozens of herbal products are reported to increase the bleeding risk in patients receiving warfarin, but very few of them could be considered “well documented.”22 Herbal products may not contain what is indicated on the label. Some herbal products simply do not contain the product that is stated, while others are adulterated with other medications, some of which could produce serious toxicity. So, even if a patient has taken 1 herbal product with prescription medications without mishap, switching to a different brand of the same herbal product may produce an adverse drug interaction. In addition, because of the lack of regulatory requirements on the accuracy of labeled amount
