Source 出处 · Shanghan Lun · Doses are not given here: they are set by a licensed practitioner for the individual.
Safety. Wu Zhu Yu Tang is built around a single movement: sending what has gone upward back down. Four ingredients do it. Wu zhu yu is acrid and hot and warms the middle; ren shen supplements; sheng jiang, in a larger proportion than most formulas carry, settles the stomach; da zao harmonises and buffers. The classical text attaches the same composition to three separate tract discussions - yangming, shaoyin and jueyin - and that is worth noticing. The picture behind all three is one picture: vomiting, or vomiting together with diarrhoea, cold in the middle, and a head that aches on top of it. The line most often quoted is the jueyin one - dry retching, spittle, and headache. What makes the formula interesting is that one composition is being read across three different frameworks; what makes it necessary to read it carefully is that the symptom it addresses is vomiting, and vomiting has one of the longest differential lists in medicine.
That list has to come first. Vomiting is produced by gastroenteritis, by gastric outlet obstruction and intestinal obstruction, by pregnancy, by uraemia, by raised intracranial pressure, by inferior-wall myocardial infarction, by ketoacidosis, and by a long line of drugs - digoxin, opioids, antibiotics, chemotherapy among them. Projectile vomiting in an infant, vomiting of bile or of blood, and vomiting with colicky pain but no passage of stool or flatus are all reasons to be assessed rather than to have the middle warmed. Headache accompanied by vomiting carries its own list. A thunderclap headache that is maximal from the first second, headache with neck stiffness or fever or altered consciousness, and a new and different headache in someone past fifty, are the presentations behind subarachnoid haemorrhage, meningitis and intracranial space-occupying lesions. Jueyin headache is a category inside the classical framework. It is not a modern diagnosis, and this entry does not present it as one.
Three cautions follow from the herbs themselves. Wu zhu yu is the fruit of Evodia (Tetradium), and it is among the herbs the Chinese pharmacopoeia annotates as having minor toxicity; liver injury has been reported in association with it, and constituents of the herb including rutaecarpine inhibit several cytochrome P450 enzymes in laboratory work, which is the reason for caution where other medicines depend on those enzymes for clearance. It is not the same plant as wu tou, whatever the resemblance in sound suggests. Ren shen is immunologically active and has documented case reports of interaction with warfarin; the direction and size of that effect are not settled, and saying the evidence is mixed is more honest than repeating either claim as established. Fresh ginger is well tolerated in food quantities and the antiplatelet concern is theoretical and weak - a small signal, not a prohibition. Jujube fruit is sugar, and this is a formula given to people who are not eating.
吴茱萸汤只做一件事：把上逆的东西送回去。四味药各司其职：吴茱萸辛热温中，人参补虚，生姜用量在诸方中偏大而重在降逆和胃，大枣调和。古典文献把同一首方挂在三处不同的讨论里 —— 阳明、少阴、厥阴，这一点值得注意。三处背后其实是同一个画面：呕吐，或吐而兼利，中焦有寒，上面还伴着头痛。被引用最多的是厥阴那一条：干呕、吐涎沫、头痛。此方有意思之处在于一首方被三个不同框架同时解读；必须谨慎读它的原因在于，它所对的是呕吐，而呕吐是医学里鉴别清单最长的症状之一。
这份清单必须排在前面。呕吐可由胃肠炎引起，也可由幽门梗阻与肠梗阻、妊娠、尿毒症、颅内压升高、下壁心肌梗死、酮症酸中毒引起，还可由一长串药物引起 —— 地高辛、阿片类、抗生素、化疗药都在其中。婴儿的喷射性呕吐、呕出胆汁或血液、以及绞痛伴不排便不排气，这些都属于应当接受评估而不是去温中的情形。头痛伴呕吐另有清单：起病瞬间即达峰值的雷击样头痛、伴颈项强直或发热或意识改变的头痛、以及五十岁以上新出现的性质不同的头痛，其背后是蛛网膜下腔出血、脑膜炎与颅内占位。厥阴头痛是古典框架内的一个类别，它不是现代诊断，本条目不把它当作诊断来呈现。
三处注意来自药物本身。吴茱萸是吴茱萸属（Evodia / Tetradium）的果实，属中国药典标注「小毒」的药材之列；与之相关的肝损伤有病例报告，其所含成分（如吴茱萸次碱）在实验研究中抑制若干细胞色素 P450 酶，这是与其他经这些酶清除的药物同用时须谨慎的理由。它读音虽近，却不是乌头。人参具免疫活性，与华法林相互作用的病例报告有文献记载，但作用方向与大小并未定论 —— 说证据混杂比把任何一方的说法当成定论更诚实。生姜在食物量级上耐受良好，抗血小板方面的顾虑是理论性的且证据较弱：这是个小信号，不是禁令。大枣是糖，而这首方恰恰是给吃不下东西的人用的。