前人在临床实践中，发现某些药物不能同用，否则就会出现药效降低或消失，甚至出现毒副作用，故有配伍禁忌之戒。《神农本草经》称这些药物之间的关系为“相恶”和“相反”。自宋以后，将“相畏”关系也列为配伍禁忌，与“相恶”混淆不清。金元时期概括为“十九畏”、“十八反 In the clinical practice, the predecessors found that certain drugs could not be used together, otherwise there would be reduction or disappearance of efficacy, and even toxic side effects, so there are incompatibility rings. The “Shen Nong Ben Cao Jing” said that the relationship between these drugs is “evil” and “opposite.” Since the Song Dynasty, the “fight” relationship has also been classified as a taboo, which is not confusing with “evil”. The golden period was summarized as “nineteen fear” and "eighteen anti