Xiao Jian Zhong Tang (Minor Construct the Middle Decoction): A Formula to Warm the Centre or Supplement Yin?

This article discusses whether Xiao Jian Zhong Tang (Minor Construct the Middle Decoction) is a formula that warms the centre or one that supplements yin. The material analysed by the authors comprises of the lines on Xiao Jian Zhong Tang in the Shang Han Lun (On Cold Damage) and Jin Gui Yao Lüe (Essential Prescriptions of the Golden Cabinet), their interpretation by commentators since the Han and Tang dynasties, and related discussions in contemporary journals. To understand the essence of the formula the authors approach it from four different perspectives: they analyse and contrast the debates in the literature, analyse signs and symptoms for which the formula is recommended, discuss its composition and consider its clinical applications. From this analysis, the authors show that the heart vexation, nosebleeds, wild dreams with seminal loss, vexing heat in the hands and feet, dry mouth and throat and the other heat signs listed amongst the indications of Xiao Jian Zhong Tang can be considered as manifestations of a cold pattern. The pathomechanism behind such symptoms is vacuity cold of the Spleen and Stomach, exuberant yin forcing out the yang, and yang vacuity with floating fire. This formula is very effective at warming the middle and dispersing cold. Clinical applications include various kinds of digestive, respiratory and haematological problems due to vacuity cold. The authors conclude that Xiao Jian Zhong Tang should be viewed as a representative formula to warm the middle and disperse cold.