摘要The infection of SARS-CoV-2 has triggered the COVID-19 pandemic.In addition to the fever and respiratory symptoms in the process of coronavirus infections,gastrointestinal symptoms,especially diarrhea,are prominent features of its acute infection and long COVID.The associations between the lung and large intestine have been demonstrated by Western medicine in aspects such as tissue origin,microflora homeostasis,mucosal immunity,renin-angiotensin system(RAS)and autonomic nervous system as well,which are considered as the evidence of material basis and potential regulatory mechanisms for"gut-lung crosstalk(肺肠串扰)"in COVID-19.We have noticed that probiotics and other preparations can regulate the intestines,and further treat COVID-19 with effective and gratifying results.In the system of traditional Chinese medicine(TCM),there's a term of"exterior-interior pairing of the lung and large intestine(肺与大肠相表里)",showing an interconnection of the lung and the bowels."Exterior-interior pairing of the lung and large intestine"is an important part of the theory of visceral activities proposed by ancient physicians through a long-term observation and practice.It's considered that"lung"and"large intestine"are interconnected and mutually exterior-interior in the normal physical activities and the disease development,providing a theoretical basis for treating lung diseases and bowel diseases from the perspective of overall concept.The study aims to compare the term of"exterior-interior pairing of the lung and large intestine"in TCM and"gut-lung crosstalk"in Western medicine regarding the development of COVID-19 and its intestinal symptoms,and provide more ideas for diagnosing and treating lung and bowel related diseases.