Xiao Xian Xiong Tang (Minor Chest-Binding Decoction) xiǎo xiàn xiōng tāng · 小陷胸汤

Safety. Xiao Xian Xiong Tang is recorded in Shanghan Lun. Three herbs, and the whole interest of the formula lies in how narrowly its indication is drawn. The classical line reads: in lesser chest binding the site is exactly below the heart, it hurts when pressed, and the pulse is floating and slippery. Two qualifiers do the work. 'Exactly below the heart' fixes a small region. 'Hurts when pressed' separates this pattern from the greater one, where the hardness runs from below the heart down to the lower abdomen and cannot be touched at all. Da Xian Xiong Tang, the greater formula, is built on da huang, mang xiao and gan sui and is among the most forceful purgative formulas in the literature; this one contains no purgative at all. The three herbs also read as an argument rather than a list. Huang lian clears the heat. Ban xia directs downward and dries. Gua lou shi is the cooling, moistening fruit that loosens what is stuck, and it is large enough in the composition to be treated as a partner to the other two rather than an addition. A second-century formula that sets a small, pressable, localised tenderness against a hardness that cannot be touched is doing something recognisable: it is grading severity by physical examination. What it was grading is not what a modern clinician would be grading, and the text does not claim otherwise. This matters because chest and upper abdominal pain has a differential that no classical text could have contained. Acute coronary syndrome, aortic dissection, pulmonary embolism, pneumothorax, pericarditis, oesophageal spasm or rupture, gastro-oesophageal reflux, biliary disease and pancreatitis all present in this region, and several of them are measured in minutes. Chest pain with breathlessness, sweating, nausea or radiation to the jaw, arm or back belongs on an emergency pathway, and so does abdominal pain with vomiting, distension and no passage of flatus or stool. Pulse and tongue examination cannot separate any of these. Safety. Both ban xia and gua lou appear in the classical list of herbs held to be antagonistic to the aconite group, so this is not a formula that would be combined with those herbs in traditional practice; that is reported here as a traditional rule, not as a demonstrated interaction. Raw ban xia is acrid and irritant to mucous membranes; only processed forms are used in dispensing practice. Huang lian contains berberine, which inhibits several drug-metabolising enzymes and transporters and displaces bilirubin, so it is unsuitable in jaundiced neonates and in G6PD deficiency; it is also constipating. Gua lou shi is the fruit of the same plant whose root is tian hua fen; they are two different herbs and not interchangeable, and the seeds are oily and may loosen the stool. Herbs of this group are traditionally cautioned in pregnancy. This library does not claim this formula resolves phlegm or treats any specific disease.