It's a troubling possibility: The herbs and drugs you take to make you healthier may, in combination, leave you worse off.  Fortunately, the Internet can provide some assistance. Information about herb-drug interactions appears in a number of places on the Web, although it differs in accessibility, cost and ease of use. 

Drugstore giant CVS has created a searchable database of interactions that is easy to use and up‑to-date. Its most visible drawback is that it is weighted toward pharmaceuticals; queries about brand-name prescription drugs produce results, while queries about herbal products with known contraindications do not. A good resource for someone on an herbal regimen who needs to check for potential problems with a newly prescribed drug.  

 MotherNature.com, a sizable natural products site, makes available a comprehensive encyclopedia of drug interactions. Clicking on the name of a drug (brand or generic) brings up a clearly organized table that lists interactions and gives medical journal references for the supporting research. 

Health Mall offers an easy‑to-read table of major interactions organized around herbal supplements. The herbs themselves and the drugs with which they may interfere are boldfaced and hyperlinked. 

Several publications have also posted useful articles explaining the dangers of herb drug interactions.

Mayohealth.org, the online newsletter of the well-known Mayo Clinic  

WebMD, a health and medical portal that has both consumer and professional audiences. 

Medical Acupuncture, the online version of a medical journal, recently carried an informative article about potential interactions with Chinese herbal products, written by a professor at the University of Southern California. Chinese preparations, which frequently combine numerous herbs in exact proportions, have not been examined in the United States to the degree that single-herb products have been.

For those taking complicated herbal or pharmaceutical regimens, the best resource may be a for-profit database. Two to consider:

Natural Medicines Comprehensive Database, compiled by and for pharmacists. Cost: $92 for 12 months. 

Interactions: The IBIS Guide to Drug‑Herb and Drug‑Nutrient Interactions. Compiled by Integrative BodyMind Information System, an alternative medical information company, and meant for use by physicians, this database is expected to be offered online soon; it is available on CD-ROM for $99.95

-- M.A.J. McKenna