Because Tibetans lived very spread out in a vast and sparsely populated territory, Tibetan medicine makes heavy use of ready-made pills. This is because Tibetans may only see their doctor once or twice a year. Therefore, Tibetan formulas tend to contain relatively low doses of each ingredient but many ingredients. By administering small doses of many different medicinals which all accomplish a similar group of functions, A) there is less likelihood for side effects from any one ingredient, and B) should the patient's symptoms change over time, one or more ingredients should cover any new symptoms. Further, because of the low doses involved, Tibetan doctors can use some very powerful but otherwise toxic ingredients, such as Ma Qian Zi (Semen Strychnotis). Therefore, such a large formula achieves very comprehensive, rounded effects.1