卫生方云。夫人身本地水火风。四大假合。阴阳和会。上焦属火为阳。下焦属水为阴。遇有
寒热。见上热下寒之疾。不能升降既济之。而反用药。实实虚虚。则水火解散。而人身坏矣。尝谓
见柳司教彭亮一曰。染瘴身热心烦。自以为实热乘渴。以冷水吞黄连黄芩丸。又取冷水以渍胸膈。
至日晡小便渐多。更服黄芩汤小柴胡汤。是夜连进数服。小便愈数。次日早。热渐才退。而即逝。可
畏哉。夫下元为人身根本。根本既虚。身乎何有。小柴胡汤。今人但知为可用退热。抑知其所以
用乎。夫仲景制方惟用之以治足少阳胆经伤寒。盖胆无出入道路。柴胡乃本经药。邪在半表半里。
非柴胡黄芩之苦。能发传经之热
则不可。佐以半夏之辛。以散除烦呕。复用人参甘草之甘。以缓中和之气。又且存攻守之意也。
倘不择其可而概用之。鲜有不蹈彭司教之辙者。大凡瘴病误用柴胡汤后。愈增烦渴。舌愈黑。身沉
重。自利频频。手稍冷。渐渐厥者。二三日决死。或发哕者。七日内死。或痰逆而哑者。七日死。
俱所目击者。或曰。若然柴胡断不可用与。余曰。柴胡能治邪气在半表。非不可用也。但必须
其症一定。不可已。方可用之。亦不可遽用。其性极寒。必须先温中。固下正气后。及十四日后。
其病退时。脉亦弦数。外症的系实热。方可用之。亦当与正气平胃养胃兼用可也。或李待制柴胡散。
尤为稳当。
《卫生方》中说：人的身体原本由地、水、火、风“四大”元素假借聚合而成，阴阳调和交会。上焦属火为阳，下焦属水为阴。如果遇到寒热交替的症状，出现上热下寒的疾病，不能通过升降气机使水火既济（即心肾相交、阴阳平衡），反而错误用药，导致实证更实、虚证更虚，那么水火之气就会离散，人体就会败坏死亡。
我曾见到柳司教彭亮说：他感染瘴气后身体发热、心中烦躁，自认为是实热证，口渴难耐，便用冷水吞服黄连丸和黄芩丸，又取冷水浸泡胸膈部位。到了傍晚时分，小便逐渐增多，他又服用黄芩汤和小柴胡汤（Chaihu Tang, Bupleurum Decoction）。当天夜里连续服用了数次，小便次数更加频繁。第二天早上，发热稍微减退，但随即病情恶化去世，真是令人畏惧啊！
下元（指肾及下焦元气）是人身体的根本，根本既然虚弱，身体还能存在什么呢？小柴胡汤，现在的人只知道它可用于退热，却不知为什么要这样使用。张仲景创制此方，专门用于治疗足少阳胆经的伤寒病。因为胆经没有直接的出入道路，柴胡是本经的药物，邪气在半表半里之间，如果不是柴胡和黄芩的苦寒之性，能够发散传经之热，那是不行的；辅以半夏的辛味，以散除烦闷和呕吐；再用人参、甘草的甘味，以缓和并补益中焦之气，这其中也包含了攻邪与守正相结合的意思。
如果不加选择地普遍使用，很少有不重蹈彭司教覆辙的。大凡瘴病误用小柴胡汤后，如果症状表现为烦躁口渴加重、舌苔变黑、身体沉重、腹泻频繁、手脚稍冷、逐渐发展为四肢厥逆的，两三天内必然死亡；或者出现呃逆（哕）的，七日内死亡；或者痰气上逆导致失声哑默的，七日内死亡。这些都是我亲眼目睹的案例。
有人问：既然如此，柴胡就绝对不可用了吗？我说：柴胡能治疗邪气在半表的病症，并非不可用。但必须症状确切符合，且病程未到不可妄用的阶段，才可以应用。也不能急于使用。因为柴胡药性偏寒，必须先温补中焦，固护下焦正气之后，等到十四日后，病情消退时，脉象呈现弦数，外在症状确系实热，才可以应用。同时也应当配合正气平胃散（Pingwei San, Poria and Atractylodes Macrocephala Powder）等调理脾胃的药物一同使用。或者使用李待制的柴胡散，更为稳妥妥当。
The *Weisheng Fang* (Prescriptions for Health Preservation) states: The human body is originally formed by the temporary aggregation of the "Four Elements" (Earth, Water, Fire, Wind). When Yin and Yang harmonize and intersect, the Upper Jiao (Upper Burner) belongs to Fire and is Yang, while the Lower Jiao (Lower Burner) belongs to Water and is Yin. If one encounters alternating chills and fever, presenting with a disease pattern of upper heat and lower cold, and fails to regulate the ascending and descending of Qi to achieve the mutual intersection of Water and Fire (i.e., the interaction between Heart and Kidney), but instead uses medication incorrectly, causing excess patterns to become more excessive and deficiency patterns to become more deficient, then the energies of Water and Fire will disperse, and the human body will deteriorate and die.
I once heard Liu Sijiao Peng Liang say: After contracting miasma (Zhang), his body became hot and he felt restless in his chest. Believing it to be an excess-heat syndrome due to thirst, he swallowed pills of Huanglian (Coptidis Rhizoma) and Huangqin (Scutellariae Radix) with cold water, and also soaked his chest and diaphragm area with cold water. By late afternoon, his urination gradually increased. He then took Huangqin Tang (Scutellaria Decoction) and Xiaochaihu Tang (Minor Bupleurum Decoction). That night, he took several doses consecutively, and his urination became even more frequent. Early the next morning, his fever subsided slightly, but he suddenly passed away. This is truly terrifying.
The Lower Yuan (the root of vitality, referring to the Kidneys and Lower Jiao Qi) is the foundation of the human body. If the foundation is depleted, how can the body exist? Xiaochaihu Tang (Minor Bupleurum Decoction): People today only know that it can be used to reduce fever, but do they understand why it is used? Zhang Zhongjing formulated this prescription specifically to treat Shaoyang Cold Damage (Shanghan affecting the Foot-Shaoyang Gallbladder Meridian). Since the Gallbladder Meridian has no direct pathways of entry and exit, Chaihu (Bupleuri Radix) is the herb of this meridian. When pathogenic factors are located at the half-exterior and half-interior level, unless the bitter-cold nature of Chaihu and Huangqin can dissipate the heat transmitted through the meridians, treatment would be ineffective. It is assisted by the acridity of Banxia (Pinelliae Rhizoma) to dissipate restlessness and vomiting, and further supplemented by the sweetness of Renshen (Ginseng Radix et Rhizoma) and Gancao (Glycyrrhizae Radix et Rhizoma) to moderate and tonify the Middle Jiao Qi. This formulation embodies the intent of both attacking pathogens and preserving healthy Qi.
If one uses it indiscriminately without selecting appropriate cases, few will avoid following the tragic path of Instructor Peng. Generally, if Miasma diseases are mistakenly treated with Xiaochaihu Tang, and symptoms worsen with increased restlessness and thirst, blackening of the tongue coating, heaviness of the body, frequent spontaneous diarrhea, slight coldness of the hands, and gradual progression to extremity coldness (Jue), death will occur within two or three days. If hiccups (Yue) develop, death occurs within seven days. If phlegm rebels upward leading to aphonia (loss of voice), death occurs within seven days. These are all cases I have witnessed personally.
Someone asked: If so, is Chaihu absolutely contraindicated? I reply: Chaihu can treat pathogenic factors at the half-exterior level; it is not absolutely unusable. However, it must be used only when the symptoms strictly match the indication and the timing is appropriate. It should not be used hastily. Its nature is extremely cold. One must first warm the Middle Jiao and consolidate the righteous Qi of the Lower Jiao. Only after fourteen days, when the disease recedes, the pulse becomes wiry and rapid, and the external symptoms are confirmed as excess-heat, may it be used. Furthermore, it should be administered concurrently with formulas that support righteous Qi and regulate the Stomach, such as Pingwei San (Poria and Atractylodes Macrocephala Powder). Alternatively, Chaihu San prepared by Li Daizhi is even more secure and appropriate.