This book's first edition (1997) was the first of its kind in addressing herbal interactions with drugs. This 4th edition keeps current with research findings and scrupulously distinguishes between what is known through (1) empirical clinical observations such as case reports, (2) data obtained from modern clinical human studies, (3) different types of laboratory research on animals and with tissues and cells. Over 2700 medical and scientific sources are cited to document these findings.

In addition, the type of preparation studied is described to emphasize differences between preparations from the same herb, along with dosage size and duration. Conflicting results are utilized to put these issues in context.

This fourth edition further highlights those combinations of herbal preparations with drugs shown to beneficially enhance therapeutic activity or reduce adverse effects, identified for 98 of the 321 herbs listed in the main text. In addition, extensive appendices organize information on these 321 and additional herbal remedies into categories addressing specific cautions, interactions with particular types of drugs, precautions for mothers, infants and children, drug interactions with vitamins and minerals, and advantageous combinations with medicines used
for inflammations, infections, cancer, and for addressing substance abuse.

The appendix sections addressing herbal influences on drug absorption and metabolism involving transport proteins, cytochrome P450 isoenzymes, and conjugating enzymes are the most extensive compilations available anywhere.