小青龍湯出自東漢張仲景著作，根據原文描述，症狀包括喘、咳、小便不利、少腹滿、倚息不得臥、其形如腫等，其描述似較接近心臟衰竭之症狀，與肺水腫等病理因素關係密切，然而依據明代醫家薛己、王肯堂與張景岳之論述，小青龍湯主治偏重呼吸系統疾病，屬肺中有形痰飲，對於心血管症狀之描述已明顯減少，其間轉變頗令人好奇。 歸納近年期刊文章，現代醫家多以小青龍湯治療呼吸道疾病，包括支氣管哮喘與慢性阻塞性肺病。依中醫觀點，這類患者常因外寒引發內飲而致病，由於小青龍湯含麻桂可宣散表邪，細辛、乾薑等藥可溫陽蠲飲，近代學者則發現小青龍湯具有鬆弛支氣管平滑肌等功效。 綜觀歷代醫學理論發展，醫家普遍認同小青龍湯可處理外寒內飲疾病，然而《傷寒論》及《金匱要略》所描述之水氣泛溢於全身，症狀接近心臟衰竭及肺水腫。明代醫家則認爲小青龍湯適用於痰飲相關之呼吸道疾病。現代中醫臨床經驗及研究皆接近明代醫家理論，可見臨床小青龍湯逐漸聚焦於肺部疾病，與仲景當時之描述不同，值得進一步的考據。

Xiao-Qing-Long-Tang (XQLT) constructed by Zhang Zhongjing, during the Eastern-Han dynasty was recorded in Shanghanlun and Jinguiyaolue. Base on the description of Zhang's writing, the symptoms including dyspnea, cough, decreased urine output, lower abdominal fullness, orthopnea, and legs edema. The above symptoms are noted in patient with congestion heart failure or pulmonary edema. However, a consensus of XQLT focusing on respiratory system diseases was emphasized by famous doctors in the Ming dynasty such as Xue Ji, Wang Kentang, and Zhang Jiebin. This change of XQLT's theory from the Eastern-Han to the Ming dynasty is fascinating.
XQLT was used to treat airway diseases, such as asthma or chronic obstructive pulmonary disease in recent years. According to the opinion of Chinese Medicine, acute exacerbation of such respiratory diseases could be induced by upper respiratory infection (URI). Herba Ephedrae and Rumulus Cinnamomi, in XQLT can improve the symptoms of URI. The other components in XQLT work on bronchial smooth muscle relaxation.
Considering the development of TCM from the Eastern-Han dynasty, the clinical doctors used XQLT to treat diseases associated with internal fluid retention induced by external cold in Chinese Medicine opinion Base on symptoms descripted in Shanghanlun and Jinguiyaolue, XQLT can treat heart failure with pulmonary edema and generalized edema. However, as the opinion of the Ming's physicians, XQLT was used to treat airway diseases associated with fluid retention. In clinical experiences and studies of Chinese Medicine, XQLT is close to theories published in the Ming dynasty. Therefore, the theories of XQLT focus on lung diseases, and differ from Zhang Zhongjing's description in the Eastern-Han. The further studies should be done for XQLT in the future.