下法首创于东汉医圣张仲景,他遵循《内经》“其下者,引而竭之,中满者,泻之于内”“结者散之,坚者削之,留者下之”的旨意,拟承气汤为下法的代表性方剂,方药简练,结构谨严,配伍适当,疗效昭著。《伤寒论》三百九十七法、一百一十三方,下法方有三十多个,泻下方十八个,承气汤居其三。《金匮要略》一百七十八方,一百四十七味药,引用承气汤药味计大黄二十一次、枳实十四次、厚朴十一次、芒硝三次、甘草 Under the law, he was first created by the Eastern Han Dynasty Medical St. Zhang Zhongjing. He followed the “Inner Scripture” “the next one, and it was exhausted. The person in the full body was diarrhea.” The purpose is to formulate Chengqitang as the representative formula of the following method. The formula is concise, the structure is strict, the compatibility is appropriate, and the curative effect is obvious. The “Treatise on Febrile Diseases,” 397 methods, 113 squares, the next French side has more than 30, diarrhea below 18, Cheng Qi Tang ranks third. The “Golden Chamber” 178, 147 taste drugs, cited Chengqi Decoction flavor rhubarb twenty times, tamping fourteen times, Magnolia eleven, Glauber’s salt three times, licorice