herbal medicine

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The study or use of medicinal herbs to prevent and treat diseases and ailments or to promote health and healing.
2. n. A drug or preparation made from a plant or plants and used for any of such purposes.

Wiktionary

1. n. herbalism
2. n. A herbal drug or similar preparation

WordNet 3.0

1. n. a medicine made from plants and used to prevent or treat disease or promote health
2. n. the use of medicinal herbs to prevent or treat disease or promote health