In a broad sense, cold disease refers to all exogenous diseases. In ancient times, it was believed that there were three major causes responsible for various diseases, namely external causes (such as pathogenic wind, cold, summer-heat, dampness, dryness and fire), internal causes (such as improper diet, physical exhaustion and emotional changes) and non-internal and non-external causes (such as wound due to fighting and bite by insects and animals). Nan Jing (Canon on Eighty-One Difficult Issues) says that there are five kinds of cold diseases, namely Zhongfeng 中风 (wind stroke), Shang han 伤寒 (cold attack), Shi wen 湿温(dampness warmth), Re bing 热病 (febrile disease) and Wen bing 温病 (warm disease).
Shang Han Za Bing Lun (Treatise on Cold Diseases and Miscellaneous Diseases) was compiled by Zhang Zhongjing (about 150-219) in the late Eastern Han Dynasty. This book deals with two kinds of diseases. In dealing with exogenous disease (cold disease), it differentiates the duration and nature of the disease according to three yang and three yin (tai yang, yang ming, shao yang, tai yin, shao yin and jue yin). It has developed specific therapeutic principle and prescriptions for each type of disease. Take tai yang disease with symptoms of fever, aversion to cold and headache for example. If there is no sweating, it can be treated by The Prescription of Mahuang Tang; if there is sweating, it should be treated by The Prescription of Guizhi Tang. In some cases both prescriptions can be used together. If the patient is weak, Ren shen can be added. If the disease is exogenous, but there is no fever, the pulse is weak and the patient is sleepy, it is shao yin disease, it can only be treated by Ren shen and Fu zi to rescue from collapse by restoring yang.
Shang Han Za Bing Lun (Treatise on Cold Diseases and Miscellaneous Diseases) was lost in history due to war. The part about cold disease was collected by Wang Shuhe, an imperial doctor in the Western Jin Dynasty, and known as Shang Han Lun (Treatise on Cold Diseases). Since it covers the theory, therapeutic principles and prescriptions for the treatment of exogenous diseases, it was and is still of great importance in medicine. The part about miscellaneous diseases in the original book was later on compiled into another book known as Jin Kui Yao Lue (Synopsis of Golden Cabinet).