干燥综合征是一种因津液不能濡润脏腑而出现一派燥象的病证。中土亏虚兼有阴火上乘、湿热蕴蒸，导致津液不得上承濡养口唇，是干燥综合征伴发唇炎的重要病机之一。甘草泻心汤在《伤寒论》中用于治疗心下痞，在《金匮要略》中用于治疗狐惑，通过分析相关条文可知，心下痞、狐惑的核心病机均为中土亏虚，甘草泻心汤可培固中土、降逆客气、清热燥湿。因此，甘草泻心汤可用于治疗中土亏虚导致的干燥综合征伴发唇炎。附验案1则，佐证上述理论，并展示相关处方用药。

Sj?gren's syndrome is a disease caused by body fluid failing to moisten the viscera and manifesting as dryness. One of the important pathogenesis of Sj?gren's syndrome complicated with cheilitis is deficiency of middle earth combined with yin-fire flaming upward and dampness-heat steaming which leads to body fluid can not flow upward to nourish the mouth and lips. In Treatise on Febrile Diseases,Gancao Xiexin Decoction（甘草泻心汤） is used to treat epigastric stuffiness,while in Synopsis of the Golden Chamber,it is used to treat Huhuo disease. By analyzing the relevant clauses,it can be seen that the core pathogenesis of epigastric stuffiness and Huhuo disease is deficiency of middle earth,and Gancao Xiexin Decoction can bank up the middle earth,descend the adverse qi,clear heat,and dry dampness. Therefore,Gancao Xiexin Decoction can be used to treat Sj?gren's syndrome complicated with cheilitis caused by deficiency of middle earth. A case is attached to prove the above theory and show the relevant prescriptions.