Traditional Chinese medicine (TCM) classic formulae have evolved over hundreds of years; however, their applications and modifications can be further developed. The classic formula Ban Xia Xie Xin Tang (Pinellia Decoction to Drain the Epigastrium; BXXXT), which was originally prescribed by Zhang Zhong-Jing in the Han dynasty (150–219), can be modified and used flexibly in treating various abdominal disorders. In the Qing dynasty (1644–1911), Wu Ju-Tong (1758–1836) wrote the book Wen Bing Tiao Bian (Systematised Identification of Warm Pathogen Diseases), outlining his eight modifications to BXXXT based on Ye Tian-Shi’s (1667–1746) clinical applications of BXXXT and its patterns. Ye applied BXXXT in two main ways. The first involved the use of bitter, pungent, dispersing and purging herbs to treat damp heat; the second was used to purge jue yin and unblock yang ming in order to treat various symptoms caused by Liver wood attacking Stomach earth. Wu followed Ye’s methodology and developed eight modifications to BXXXT. These can treat summer heat-damp (shu shi), lurking summer heat (fu shu) and damp-warm (shi wen) conditions. They can also treat jue yin Liver conditions or Liver Qi attacking Stomach patterns. This article discusses the use of Wu Ju-Tong’s eight modifications. Modern clinical cases including nausea, vomiting, abdominal distension, stomach ache, diarrhoea and infertility have been used as examples to illustrate the flexible use of BXXXT.