With the growing interest in herbalism and making one's own plant preparations, people often dive in without really considering the ethical, environmental, and health impacts herb sourcing has. What kind of environment did your herbs grow in? What was in their soil, their water, or what was sprayed on them? Who harvested them, processed them? Were they fairly compensated for their efforts? These are the questions we should ask ourselves.
There are different categories of Herbs that interact with the immune system, most commonly known as Immunostimulants, Immunomodulators, and Adaptogens. Other groups - which are not necessarily exclusive, Herbs can have actions that can put them in multiple categories - include Antimicrobial and Antiviral.