Herbal Medicine is the use of plant, animal, and mineral compounds to affect body function. Various compounds in their natural state have been identified in having particular biological action since recorded history. The use of herbs in TCM does not separate its components from its natural state, which preserves the synergy of chemical structures within the herb. When the herb is used responsibly, it retains its safety and desired outcome, without side affects. A single herb is rarely used in a TCM prescription. Herbs are combined based on the diagnosed syndrome, and where in the body the syndrome is located. A TCM herbal prescription will have in it one or more chief herbs, assisting herbs, and adjunct herbs. A chief herb is one that creates the most change. An assisting herb can strengthen and modify a chief herb's function. An adjunct herb can act to synergistically "blend" the formula, and reduce toxicity of selected herbs. This way of combining herbs allows a more personalized prescription specific for the individual and health complaint. I only use herbs from companies that have tested for impurities, heavy metals, fungicide, pesticides, and correct species.