How do herbs work?

In plenty of cases, scientists aren' t sure what specific ingredient in a specific herb works to treat a condition or disease. Whole herbs contain plenty of ingredients, & they may work together to produce a beneficial effect. Plenty of factors decide how effective an herb will be. For example, the type of surroundings (climate, bugs, soil quality) in which a plant grew will affect it, as will how & when it was harvested & processed.