And so Chinese medicinal ingredients are rarely employed by themselves in singular attacks on a germ or ailment. Instead ingredients in prescriptions play one of four different roles: "monarch, minister, assistant or guide." Based on the particulars of the illness and on whether the patient's constitution is characterized by "insufficiency or excess, heat or cold," the doctor will adjust the prescription.
因此中藥也很少只以單方殺一種病菌、而是以方劑（復方）治療，藥材有君、臣、佐、使之分，醫師依著患者虛、寒、實、熱不同的體質、病情來增減藥量、靈活配藥。