Source 出处 · Taiping Huimin Hejiju Fang · Doses are not given here: they are set by a licensed practitioner for the individual.
Safety. Su Zi Jiang Qi Tang is recorded in Taiping Huimin Hejiju Fang, the Song-dynasty official formulary, and it is one of the clearest surviving examples of a formula built around a single directional claim: the breath should go down. Its classical description is excess above, deficiency below — phlegm and congestion filling the chest while the lower source, described as the kidney's grasping of qi, has grown too weak to hold the breath. Perilla fruit and pinellia descend and transform; peucedanum and magnolia open the chest and move what has accumulated; cassia bark warms the lower burner; Chinese angelica appears in a breathing formula, which looks odd until one accepts that classical texts treat the blood aspect as inseparable from the holding of qi; honey-fried licorice guards the middle.
What matters for a modern reader is that excess above, deficiency below is a piece of classical mechanism rather than a diagnosis, and that the kidney in this sentence is the kidney of Chinese medicine's functional system, not the organ measured by a creatinine result. The cluster the formula was used for — chronic cough, wheeze, breathlessness worse on lying flat, copious white sputum — is now distributed across COPD, asthma, heart failure, bronchiectasis and interstitial lung disease, and those have very different treatments. Acute breathlessness is an emergency, not a pattern to be differentiated first. Breathlessness that is new, that wakes someone at night, that comes with chest pain, coughing blood, swelling of one leg, or fever needs assessment the same day, because pulmonary embolism, pneumothorax and cardiac causes all present this way and none of them waits for a formula.
Safety notes. Pinellia must be processed: raw pinellia's calcium oxalate raphides and lectins can cause severe throat swelling and threaten the airway, and it is traditionally held incompatible with aconite-type herbs. Magnolia bark comes from Magnolia officinalis, a species under genuine harvesting pressure; the bark is also used in neighbouring traditions, and the honest statement is that supply chains are not always what the label says. Cassia bark is Cinnamomum cassia rather than Ceylon cinnamon, and carries appreciably more coumarin, for which European food safety bodies have set a tolerable daily intake on liver findings. Dang gui contains furanocoumarins and has case reports of interaction with warfarin; it is sometimes marketed to western buyers as a hormone, and there is no good evidence for that claim. Qian hu is Peucedanum, another furanocoumarin-containing umbellifer with photosensitivity concerns and a long history of substitution between species. Perilla fruit is an oily seed, and the genus contains perilla ketone, which has caused pulmonary oedema in grazing animals, although no corresponding risk has been established for human preparations. And honey-fried licorice again: potassium, blood pressure and oedema, in relation to amount, duration and the other medicines a person is already taking.
苏子降气汤著录于《太平惠民和剂局方》，是「一个方向性主张」保存得最清楚的方剂之一：气该往下走。它的传统病机表述是「上实下虚」—— 痰与壅塞充塞于上，而下面那个被说成「肾主纳气」的本源已经弱到收不住气。紫苏子与半夏降气化痰，前胡与厚朴开胸散壅，肉桂温下元；当归出现在一首治喘的方里显得突兀，原因是古典文献把血这一层与「气之摄纳」看作不可分；炙甘草守中。
今天读它，要紧的是：「上实下虚」是一段古典病机推演，不是诊断；这句话里的「肾」是中医功能系统的肾，不是化验单上肌酐所测的那个器官。它所对应的症状群 —— 慢性咳嗽、喘息、平卧加重、痰多色白 —— 现在分布在慢阻肺、哮喘、心衰、支气管扩张与间质性肺病之间，而这几样的治疗差别很大。急性呼吸困难是急症，不是先辨证的场合。新发的、夜间憋醒的、伴胸痛或咯血或单侧下肢肿或发热的呼吸困难，都要当天评估：肺栓塞、气胸与心源性原因都以这种方式起病，没有一样会等一首方。
安全提示。半夏必须炮制：生品的草酸钙针晶与凝集素可致严重咽喉肿痛并威胁气道，传统亦不与乌头类同用。厚朴为 Magnolia officinalis 之树皮，采伐压力是真实存在的；该树皮在邻近传统里也用，诚实的一句是：供应链并不总是与标签一致。肉桂是 Cinnamomum cassia（中国肉桂）而非锡兰肉桂，香豆素含量明显更高，欧洲食品安全机构基于肝脏方面的发现为其设定了可耐受日摄入量。当归含呋喃香豆素，与华法林有病例报告的相互作用；它有时被当作「植物雌激素」推介给西方买家，这一点没有可靠证据。前胡是 Peucedanum，又一种含呋喃香豆素的伞形科药，有光敏顾虑与种间混用的长久历史。紫苏子是油性的种子，紫苏属含紫苏酮，曾在放牧牲畜中引起肺水肿，而人类制剂是否对应此风险未被证实。炙甘草仍是那一条：血钾、血压、水肿，与所用多少、服用时长以及正在同服的药相关。