Xiao Chai Hu Tang is one of the most famous Chinese formulas because it treats a uniquely Chinese syndrome of “half-interior/ half exterior” (among other things). Books have been written about it and it is hotly debated up to the present and certainly into the future. It shows up first in the Shang Han Lun book in line 37.
太阳病 Tai Yang Bing，日已去，10 days already resolved
脉浮细而嗜卧者，floating thin pulse and wants to lie down
外已解也。Exterior already resolved.
设胸满胁痛者，fullness in chest, pain in ribs
与小柴胡汤，use Xiao Chai Hu Tang
Xiao Chai Hu Tang can do miracles but is easily misprescribed so be cautious. It has certainly been used a lot in Japan especially to help with symptoms of chronic hepatitis. However, it should not be used with interferon treatments! (Not sure about current HCV medications but those work so well that I wouldn’t take any herbs with it unless needed for something else.)