Source 出处 · Shanghan Lun · Doses are not given here: they are set by a licensed practitioner for the individual.
Safety. Four ingredients. Dried ginger against scutellaria and coptis, with ginseng alongside. That is the whole formula, and the opposition is the point: one hot herb and two cold ones in the same decoction, which is the pattern later writers called 寒热格拒 — cold and heat refusing each other, heat above unable to descend, cold below unable to receive.
The line reads 伤寒本自寒下，医复吐下之，寒格更逆吐下，若食入口即吐，干姜黄芩黄连人参汤主之. Read it slowly: there was cold below to begin with, the practitioner then applied emesis and purgation, the blockage got worse, and now food is vomited the moment it enters the mouth. Like Chaihu Guizhi Ganjiang Tang and Mahuang Shengma Tang in this batch, the source names the treatment that preceded the deterioration. The classical text is not shy about this; modern quoting of these lines usually drops it.
食入口即吐 is the phrase worth stopping at, because it is not the same as ordinary nausea. Vomiting at the moment of swallowing has a short and fairly surgical list: gastric outlet obstruction, pyloric stenosis, duodenal obstruction, malrotation with volvulus in an infant, achalasia and oesophageal stricture, severe gastroparesis, pancreatitis and cholecystitis, bowel obstruction, raised intracranial pressure, diabetic ketoacidosis and adrenal crisis, uraemia, hyperemesis gravidarum, drug effects from opioids, GLP-1 receptor agonists or chemotherapy, and — again, and always — inferior wall myocardial ischaemia. In a young infant, effortless projectile vomiting without bile and without much abdominal pain is hypertrophic pyloric stenosis until an ultrasound says otherwise, and that is a surgical condition with an electrolyte problem attached to it.
The classical framing puts 干姜 at the top for the cold below and 黄芩、黄连 for the heat above. Modern pharmacology reads those two cold herbs rather differently from a formula chart. 黄连 is coptis, and its berberine is a demonstrated inhibitor of CYP3A4, CYP2D6 and P-glycoprotein; there are case reports of it raising cyclosporine and tacrolimus concentrations to clinically relevant degrees, which matters directly to anyone on a transplant regimen. Berberine also displaces bilirubin from albumin, which is why it is treated as unsuitable in jaundiced newborns and during pregnancy and breastfeeding — kernicterus is not a theoretical endpoint. 黄芩 carries the Scutellaria baicalensis versus Scutellaria lateriflora identification problem and the liver injury reports that travel with it. 人参 has the warfarin and hypoglycaemia reports. 干姜 is dried ginger, not fresh ginger and not galangal. 黄连 is not 胡黄连, which is an entirely different plant.
None of this makes the formula interesting as something to try. What makes it worth holding in a knowledge base is the structure: four herbs, two of them directly opposed, and a source line that names the practitioner's own intervention as part of the cause.
四味药。干姜对着黄芩、黄连，人参在一旁。整首方就这些，而对立本身就是要点：一味大热与两味苦寒同在一碗里，这就是后人说的「寒热格拒」—— 上热不得降、下寒不得纳。
条文的措辞值得逐字读：「伤寒本自寒下，医复吐下之，寒格更逆吐下，若食入口即吐，干姜黄芩黄连人参汤主之。」原本就有下寒，医者又用吐法与下法，格拒更逆，于是食物一入口就吐。和本批的柴胡桂枝干姜汤、麻黄升麻汤一样，**文献把导致恶化的那次治疗写了进去**。古典文献对此并不讳言，而今天引用这些条文时通常把这一句省掉。
「食入口即吐」是要停下来的那四个字，它不等于一般的恶心。**一咽下就吐，清单很短而且偏外科**：胃出口梗阻、幽门狭窄、十二指肠梗阻、婴儿肠旋转不良伴扭转、贲门失弛缓与食管狭窄、重度胃轻瘫、胰腺炎与胆囊炎、肠梗阻、颅内压升高、酮症酸中毒与肾上腺危象、尿毒症、妊娠剧吐、阿片类／GLP-1 受体激动剂／化疗的药物效应，以及 —— 再一次 —— 下壁心肌缺血。婴儿若出现无胆汁、腹痛不明显的喷射性呕吐，在超声排除之前按**肥厚性幽门狭窄**处理，那是外科情况且带着电解质问题。
古典把干姜列在前面治下寒，黄芩、黄连治上热。现代药理读这两味苦寒药的方式与方解不同：黄连含小檗碱，是已被证实的 CYP3A4／2D6／P-糖蛋白抑制剂，有升高环孢素与他克莫司浓度到临床相关程度的病例报告 —— 对移植后服药的人这直接关系到用药安全；小檗碱还置换胆红素，故黄疸新生儿与孕期哺乳期视为不宜，**核黄疸不是理论终点**。黄芩有 Scutellaria baicalensis 与美黄芩的误判问题及其肝损伤病例报告。人参有华法林与低血糖的报告。干姜不是生姜、也不是高良姜；**黄连不等于胡黄连**（完全不同的另一味药）。
这些都不构成「值得一试」的理由。它值得进知识库的是结构本身：四味药、两味正相对，而文献把自己的那次干预写进了病因。