Plant remedies exist as folk medicine across cultural communities, and some Western physicians are already using plant medicines for yellow fever (such as True Ipecac from South America and lobelia). Thomson begins using a combination of remedies, including lobelia, to induce vomiting, as well as "a purgative to cleanse the bowels and the use of a sweat bath." Within two years, this proves a much more effective method for healing yellow fever. Thomson learns most of his remedies and practices from Indigenous healers, although he never acknowledges them in the development of his framework.