柴胡（半斤味苦微寒） 黄芩（三两味苦寒） 人参（三两味甘温） 甘草（三两
味甘平） 半夏（半升洗味辛温） 生姜（三两切味辛温） 大枣（十三擘味甘平）
上七味。以水一斗二升。煮取六升。去滓。再煎。取三升。温服一升。日三服。
内经曰。热淫于内。以苦发之。柴胡黄芩之苦。以后传邪之热。里不足者。以甘缓
之。人麦甘草之甘。以缓中和之气。邪半入里。则里气逆。辛以散之。半夏以除烦呕。邪
半在表。则荣卫争之。辛甘解之。姜枣以和荣卫。
成氏云。伤寒邪气在表者。必渍形以为汗。邪气在里者。必荡涤以取利。其于不外不
内。半表半里。是当和解则可也。小柴胡。和解表里之剂。
王三阳云。此证在半表半里。或中风。或伤寒。三四日得之也。或有传经而得。或
直中此经。始终不传者。医人但见一证。而以脉合之。盒饭照此方治药。不可汗下。亦
不可求诸证悉具也。
后加减法
若胸中烦而不呕。去半夏人参。加栝蒌实一枚。
胸中烦而不呕。热聚而气不逆也。甘者令人中满。方热聚。无用人参之补。辛散
逆气。既不呕。无用半夏之辛。温热宜寒。疗聚宜苦。栝蒌实苦寒。以泄胸中蕴热。若
渴者。去半夏。加人参。合前成四两半。栝蒌根四两。
半夏燥津液。非渴者所宜。人参甘而润。栝蒌根苦而凉。彻热生津。二物为当。
若腹中痛者。去黄芩。加芍药三两。
去黄芩。恶寒中。加芍药。以通壅。
若胁下痞硬。去大枣。加牡蛎四两。
甘令人中满。痞者。去大枣之甘。咸以软之。痞硬者。加牡蛎之咸。
王三阳云。不如枳桔稳当。
若心下悸。小便不利者。去黄芩、加茯苓四两。
饮而水蓄不行为悸。小便不利。内经曰。肾欲坚。急食苦以坚肾。则水益坚。故去
黄芩。淡味渗泄为阳。茯苓甘淡。以泄伏水。
若不渴。外有微热者。去人参。加桂三两。温覆。取微汗。愈。
不渴者。里和也。故去人参。外有微热。表未解也。加桂以发汗。
王三阳云。加桂句。亦要顾寒多热少。
若咳者。去人参、大枣、生姜。加五味子半升。干姜二两。
咳者。气逆也。甘则壅气。故去人参大枣。内经曰。肺欲收。急食酸以收之。五味
子之酸。以收逆气。肺寒则咳。散以辛热。故易生姜以干姜之热也。
娄氏云。亦有肺热而嗽者。亦有风邪未散而嗽者。但咳与嗽不同。五味干姜当斟酌。
血弱气尽。腠理开。邪气因入。与正气相搏。结于胁下。正邪分争。往来寒热。休
作有时。默默不欲饮食。脏腑相连。其痛必下。邪高痛下。故使呕也。小柴胡汤主之。
人之气血。随时盛衰。当月郭空之时。则为血弱气尽。腠理开疏之时也。邪气乘虚。
伤人则深。针经曰。月郭空。则海水东盛。人血气虚。卫气去。形独居。肌肉减。皮肤
缓。腠理开。毛发残。 理薄。烟垢落。当是时。遇贼风。则其入深者是矣。邪因正虚。
自表之里。而结于胁下。与正分争。作往来寒热。默默不欲饮食。此为自外之内。经络
与脏腑相连。邪气随经必传于里。故曰。其痛下。痛、一作病。邪在上焦为邪高。邪渐
传里为痛下。里气与邪气相搏。逆而上行。故使呕也。与小柴胡汤。以解半表半里之邪。
服柴胡汤已。渴者、属阳明也。以法治之。
服小柴胡汤。表邪已而渴。里邪传于阳明也。以阳明治之。
王三阳云。前条渴者去半夏。柴胡证已具。未服柴胡汤。先见渴证者也。此条渴者。
已服柴胡汤。外证已除而又渴者也。
得病六七日。脉迟浮弱。恶风寒。手足温。医二三下之。不能食。而胁下满痛。面
目及身黄。颈项强。小便难者。与柴胡汤。后必下重。本渴而饮水。呕者。柴胡汤不中
与也。食谷者哕。
因下之而胁痛。不可与柴胡。
得病六七日。脉迟浮弱。恶风寒。手足温。则邪气在半表半里。未为实。反二三下
之。虚其胃气。损其津液。邪蕴于里。故不能食而胁下满痛。胃虚。为热蒸之。熏发于外。
面目及身悉黄也。颈项强者。表仍未解也。小便难者。内亡津液。虽本柴胡汤证。然以
里虚。下焦气涩。而小便难。若与柴胡汤。又走津液。后必下重也。不因饮水而呕者。
柴胡汤证。若本因饮而呕者。水停心下也。金匮要略曰。先渴却呕者。为水停心下。此
属饮家。饮水者。水停而呕。食谷者。物聚而哕。皆非小柴胡汤
所宜。二者皆柴胡汤之戒。不可不识也。
伤寒四五日。身热、恶风。颈项强。胁下满。手足温而渴者。小柴胡汤主之。
上文宜用柴胡而反下之道。至胁痛项强。小便难利。柴胡为药剂。若本病项强胁满
者。正宜用柴胡而非其例矣。故申言之。
身热、恶风。颈项强者。表未解也。胁下满而渴者。里不和也。邪在表。则手足通
热。邪在里。则手足厥寒。今手足温者。知邪在表里之间也。与小柴胡汤。以解表里之
邪。
伤寒。阳脉涩。阴脉弦。法当腹中急痛者。先与小建中汤。不瘥者。与小柴胡汤主
之。
脉阳涩阴弦。而腹中急痛者。当作里有虚寒治之。与小建中汤。温中散寒。若不瘥
者。非里寒也。必由邪气自表之里。里气不利所致。与小柴胡汤。去黄芩。加芍药。以
除传里之邪。
【小柴胡汤方第三十八】
柴胡（半斤，味苦微寒） 黄芩（三两，味苦寒） 人参（三两，味甘温） 甘草（三两，味甘平） 半夏（半升，洗净，味辛温） 生姜（三两，切片，味辛温） 大枣（十三枚，掰开，味甘平）
以上七味药。用水一斗二升。煮取六升药液。滤去药渣。再次煎煮。取三升药液。每次温服一升。每日服用三次。
《内经》说：热邪蕴结于体内，应用苦味药发散。柴胡、黄芩的苦味，用于疏散由表传里的邪热。里气不足者，应用甘味药缓急。人参、甘草的甘味，用于缓和中和之气。邪气半入里，则里气上逆，应用辛味药散之。半夏用于消除烦闷和呕吐。邪气半在表，则营卫相争，应用辛甘药解之。生姜、大枣用于调和营卫。
成无己说：伤寒邪气在表，必须通过浸渍形体来发汗；邪气在里，必须通过荡涤来通便取利。至于邪气既不在表也不在里，而在半表半里之间，此时应当采用和解法。小柴胡汤是和解表里的方剂。
王三阳说：此证位于半表半里，可能是中风，也可能是伤寒，通常在发病三四天时出现。有的由他经传变而来，有的直接中于此经，始终不传变的。医生只要见到其中一个症状，并结合脉象，就应当按照此方用药治疗。不可用发汗或攻下法，也不可要求所有症状都具备才用药。
【后续加减法】
如果胸中烦闷但不呕吐，去掉半夏、人参，加栝蒌实一枚。
胸中烦闷但不呕吐，说明热邪聚结而气机未上逆。甘味药令人中满，既然热邪聚结，就不用人参的补益作用；辛味药散逆气，既然不呕吐，就不需要半夏的辛散。温热病宜用寒凉药，治疗热聚宜用苦味药。栝蒌实质味苦寒，可泄除胸中蕴积的热邪。
如果有口渴症状，去掉半夏，加人参，与前药合计共四两半，再加栝蒌根四两。
半夏燥伤津液，不适合口渴者。人参味甘而润，栝蒌根味苦而凉，能清热生津，这两味药适宜使用。
如果腹中疼痛，去掉黄芩，加芍药三两。
去掉黄芩，是因为厌恶寒凉伤中；加芍药，是为了通利壅滞。
如果胁下痞塞硬满，去掉大枣，加牡蛎四两。
甘味药令人中满，痞塞者，应去掉大枣的甘味。咸味药能软坚散结，痞硬者，加牡蛎的咸味。
王三阳说：不如用枳壳、桔梗稳妥。
如果心下悸动，小便不利，去掉黄芩，加茯苓四两。
水饮停蓄不行导致心悸，小便不利。《内经》说：肾欲坚，急食苦以坚肾，则水益坚。所以去掉黄芩。淡味药具有渗泄作用属阳。茯苓味甘淡，能泄除伏留之水。
如果不渴，体表有轻微发热，去掉人参，加桂枝三两，盖被保暖，取微汗，病愈。
不渴，说明里气和顺，所以去掉人参。体表有微热，说明表邪未解，加桂枝以发汗。
王三阳说：加桂枝这一句，也要顾及寒多热少的情况。
如果咳嗽，去掉人参、大枣、生姜，加五味子半升，干姜二两。
咳嗽是气机上逆。甘味药会壅滞气机，所以去掉人参、大枣。《内经》说：肺欲收，急食酸以收之。五味子的酸味，用以收敛逆气。肺寒则咳，应用辛热药发散，所以将生姜换成干姜的温热之性。
娄氏说：也有肺热而嗽的，也有风邪未散而嗽的。但咳与嗽不同，五味子和干姜的使用应当斟酌。
血弱气尽，腠理开，邪气因入，与正气相搏，结于胁下。正邪分争，往来寒热，休作有时。默默不欲饮食。脏腑相连，其痛必下。邪高痛下，故使呕也。小柴胡汤主之。
人体的气血随时间盛衰，在月郭空之时，就是血弱气尽、腠理开疏的时候。邪气乘虚伤人则深。《针经》说：月郭空，则海水东盛，人血气虚，卫气去，形独居，肌肉减，皮肤缓，腠理开，毛发残，腠理薄，烟垢落。在这个时候，遇到贼风，邪气就会深入。邪气因正气虚弱，从表入里，结于胁下，与正气分争，出现往来寒热、默默不欲饮食。这是自外之内，经络与脏腑相连，邪气随经必传于里，所以说“其痛下”。痛，一作病。邪在上焦为邪高，邪渐传里为痛下。里气与邪气相搏，逆而上行，所以引起呕吐。给予小柴胡汤，以解除半表半里之邪。
服用柴胡汤后，出现口渴的，属于阳明病，按阳明法治之。
服用小柴胡汤，表邪已解而口渴，是里邪传入阳明。按阳明病治疗。
王三阳说：前条提到的口渴，是去半夏的人参证，柴胡证已具备，但未服柴胡汤之前先见口渴证的。本条提到的口渴，是已服柴胡汤，外证已除而又出现口渴的。
得病六七日，脉迟浮弱，恶风寒，手足温。医生反复攻下，导致不能食，且胁下满痛，面目及身黄，颈项强，小便难。若给予柴胡汤，之后必然出现下重感。本来口渴而饮水后呕吐的，柴胡汤不适用。进食后呃逆的。
因为攻下导致胁痛，不可与柴胡汤。
得病六七日，脉迟浮弱，恶风寒，手足温，说明邪气在半表半里，尚未成实证。反而反复攻下，损伤胃气，耗损津液，邪气蕴结于里，所以不能食且胁下满痛。胃虚，被热邪蒸腾，熏发于外，导致面目及全身发黄。颈项强，说明表邪仍未解。小便难，是因为内部津液亡失。虽然本是柴胡汤证，但因为里虚，下焦气机涩滞，导致小便难。若给予柴胡汤，又会耗走津液，之后必然出现下重感。不因饮水而呕吐的，若是柴胡汤证。如果本是因饮水而呕吐的，是水停心下。《金匮要略》说：先渴却呕者，为水停心下，这属于饮家。饮水者，水停而呕；食谷者，物聚而哕。这些都不是小柴胡汤所适宜的。这两种情况都是柴胡汤的禁忌，不可不认识。
伤寒四五日，身热、恶风，颈项强，胁下满，手足温而渴者，小柴胡汤主之。
上文提到宜用柴胡却反用下法，导致胁痛项强、小便难利等变证。如果是原本病症就有项强胁满的，正是适宜用柴胡汤的情况，而非上述变例。所以重申说明。
身热、恶风，颈项强，说明表邪未解。胁下满而渴，说明里不和。邪在表，则手足通常发热；邪在里，则手足厥冷。现在手足温暖，可知邪气在表里之间。给予小柴胡汤，以解除表里之邪。
伤寒，阳脉涩，阴脉弦，法当腹中急痛者，先与小建中汤。若不愈者，与小柴胡汤主之。
脉象阳涩阴弦，且腹中急痛，应当当作里有虚寒治疗，给予小建中汤，温中散寒。若不愈，说明不是里寒，必定是由邪气自表入里，里气不利所致。给予小柴胡汤，去掉黄芩，加芍药，以清除传入里的邪气。
[Formula 38: Xiao Chai Hu Tang (Minor Bupleurum Decoction)]
Chai Hu (Bupleuri Radix, half jin, bitter flavor, slightly cold) Huang Qin (Scutellariae Radix, three liang, bitter flavor, cold) Ren Shen (Ginseng Radix, three liang, sweet flavor, warm) Gan Cao (Glycyrrhizae Radix et Rhizoma, three liang, sweet flavor, neutral) Ban Xia (Pinelliae Tuber, half sheng, washed, pungent flavor, warm) Sheng Jiang (Zingiberis Rhizoma Recens, three liang, sliced, pungent flavor, warm) Da Zao (Jujubae Fructus, thirteen pieces, torn open, sweet flavor, neutral)
The above seven herbs. Boil in one dou and two sheng of water. Reduce to six sheng of liquid. Strain the dregs. Re-boil. Reduce to three sheng of liquid. Take one sheng warm each time. Administer three times daily.
The *Nei Jing* (Inner Canon) states: When heat is rampant internally, use bitter flavors to disperse it. The bitterness of Chai Hu and Huang Qin disperses the pathogenic heat transmitted from the exterior to the interior. When the interior qi is deficient, use sweet flavors to moderate it. The sweetness of Ren Shen and Gan Cao moderates the middle qi. When pathogenic factors are halfway into the interior, the interior qi becomes rebellious; use pungent flavors to scatter them. Ban Xia eliminates vexation and vomiting. When pathogenic factors are halfway at the exterior, Ying (Nutritive) and Wei (Defensive) qi contend; use pungent and sweet flavors to resolve them. Sheng Jiang and Da Zao harmonize Ying and Wei qi.
Cheng Wuji stated: When Shaoyin pathogenic factors are at the exterior, they must be treated by soaking the form to induce sweating. When pathogenic factors are at the interior, they must be treated by purging to obtain bowel movements. For those that are neither strictly exterior nor strictly interior, but located at the Shaoyang level (half-exterior, half-interior), reconciliation is the appropriate method. Xiao Chai Hu Tang is a formula for reconciling the exterior and interior.
Wang Sanyang stated: This syndrome occurs at the half-exterior, half-interior level. It may result from Wind Strike or Cold Damage, typically appearing on the third or fourth day. It may arise from transmission from another channel, direct invasion of this channel, or remain without transmission. The physician need only observe one symptom and correlate it with the pulse to treat according to this formula. Sweating or purging methods are contraindicated. One should not wait for all symptoms to manifest before prescribing.
[Subsequent Modifications]
If there is vexation in the chest without vomiting, remove Ban Xia and Ren Shen, add one Gua Lou Shi (Trichosanthis Fructus).
Vexation in the chest without vomiting indicates heat aggregation without rebellious qi. Sweet flavors cause fullness in the middle; since heat is aggregated, the tonifying nature of Ren Shen is unnecessary. Pungent flavors scatter rebellious qi; since there is no vomiting, the pungent dispersion of Ban Xia is unnecessary. For warm-heat conditions, cold herbs are suitable; for treating heat aggregation, bitter herbs are suitable. Gua Lou Shi is bitter and cold, clearing accumulated heat in the chest.
If there is thirst, remove Ban Xia, add Ren Shen (totaling four liang and half with previous ingredients), and add Gua Lou Gen (Trichosanthis Radix) four liang.
Ban Xia dries body fluids and is unsuitable for thirst. Ren Shen is sweet and moistening; Gua Lou Gen is bitter and cool, clearing heat and generating fluids. These two are appropriate.
If there is abdominal pain, remove Huang Qin, add Bai Shao (Paeoniae Radix Alba) three liang.
Remove Huang Qin to avoid harming the middle with cold; add Bai Shao to unblock stagnation.
If there is a sensation of fullness and hardness under the ribs, remove Da Zao, add Mu Li (Ostreae Concha) four liang.
Sweet flavors cause fullness; for fullness, remove the sweetness of Da Zao. Salty flavors soften hardness; for hardness, add the salinity of Mu Li.
Wang Sanyang stated: Using Zhi Ke (Aurantii Fructus) and Jie Geng (Platycodonis Radix) is more stable.
If there is palpitation in the epigastrium and difficult urination, remove Huang Qin, add Fu Ling (Poria) four liang.
Fluid retention causing palpitation and difficult urination. The *Nei Jing* states: The Kidney desires firmness; urgently eat bitter to firm the Kidney, then water becomes firmer. Thus, remove Huang Qin. Bland flavors have permeating and draining properties belonging to Yang. Fu Ling is sweet and bland, draining retained water.
If there is no thirst but slight external fever, remove Ren Shen, add Gui Zhi (Cinnamomi Ramulus) three liang. Cover with blankets to induce slight sweating. The disease resolves.
No thirst indicates harmony in the interior, so remove Ren Shen. Slight external fever indicates unresolved exterior pathogens; add Gui Zhi to induce sweating.
Wang Sanyang stated: Regarding adding Gui Zhi, one must also consider cases where cold predominates over heat.
If there is coughing, remove Ren Shen, Da Zao, and Sheng Jiang; add Wu Wei Zi (Schisandrae Fructus) half sheng and Gan Jiang (Zingiberis Rhizoma) two liang.
Coughing indicates rebellious qi. Sweet flavors obstruct qi, so remove Ren Shen and Da Zao. The *Nei Jing* states: The Lung desires consolidation; urgently eat sour to consolidate it. The sourness of Wu Wei Zi consolidates rebellious qi. Cold in the Lung causes coughing; disperse with pungent-hot herbs. Thus, replace Sheng Jiang with the hot nature of Gan Jiang.
Lou Shi stated: There are also cases of cough due to Lung heat or lingering wind pathogens. Cough (ke) and phlegm-rattling cough (sou) differ; the use of Wu Wei Zi and Gan Jiang requires discretion.
When blood is weak and qi is exhausted, the interstices (Cou Li) open, allowing pathogenic factors to enter. They contend with righteous qi, knotting below the hypochondrium. Righteous and pathogenic qi struggle, resulting in alternating chills and fever occurring at intervals. There is silence and lack of desire for food. Because the zang-fu organs are connected, pain must radiate downward. Pathogenic factors are high (upper jiao), pain is low (lower abdomen), thus causing vomiting. Xiao Chai Hu Tang governs this.
Human qi and blood fluctuate with time. During the new moon (when the moon's orb is empty), blood is weak and qi is exhausted, and the Cou Li are open and sparse. Pathogenic factors take advantage of deficiency to injure deeply. The *Zhen Jing* (Needle Canon) states: When the moon's orb is empty, the eastern sea swells; human qi and blood become deficient, Wei Qi departs, the form remains alone, muscles diminish, skin relaxes, Cou Li open, hair becomes sparse, interstices thin, and soot-like dust falls. At this time, encountering treacherous winds, pathogenic factors penetrate deeply. Due to righteous deficiency, pathogens move from exterior to interior, knotting below the hypochondrium, contending with righteous qi, producing alternating chills and fever, and silence with anorexia. This is from exterior to interior; meridians connect with zang-fu. Pathogens follow the meridian to transmit to the interior, hence "pain radiates downward." Pain (or disease): Pathogens in the upper jiao are "high"; as they transmit to the interior, pain is "low." Interior qi contends with pathogens, rebelling upward, causing vomiting. Administer Xiao Chai Hu Tang to resolve pathogens at the half-exterior, half-interior level.
After taking Xiao Chai Hu Tang, if thirst develops, it belongs to the Yangming stage. Treat according to Yangming principles.
After taking Xiao Chai Hu Tang, if exterior pathogens are resolved but thirst appears, interior pathogens have transmitted to Yangming. Treat Yangming.
Wang Sanyang stated: In the previous clause regarding thirst, the Ban Xia was removed because the Chai Hu syndrome was established, and thirst appeared before taking the decoction. In this clause, thirst appears after taking the decoction, when exterior symptoms have been eliminated.
On the sixth or seventh day of illness, with a slow, floating, and weak pulse, aversion to wind and cold, and warm hands and feet. If the physician purges repeatedly, leading to inability to eat, fullness and pain below the hypochondrium, yellowing of the face, eyes, and body, stiffness of the neck and nape, and difficult urination. If Chai Hu Tang is given, heaviness in the rectum will likely follow. If originally thirsty and vomiting after drinking water, Chai Hu Tang is inappropriate. If vomiting occurs after eating, it is [contraindicated].
Because purging caused hypochondriac pain, Chai Hu Tang is contraindicated.
On the sixth or seventh day of illness, with a slow, floating, and weak pulse, aversion to wind and cold, and warm hands and feet, indicating pathogens at the half-exterior, half-interior level, not yet excess. Repeated purging damages Stomach qi and consumes fluids, trapping pathogens in the interior. Hence, inability to eat and hypochondriac fullness/pain. Stomach deficiency allows heat to steam outward, causing generalized yellowing. Neck stiffness indicates unresolved exterior pathogens. Difficult urination results from internal fluid depletion. Although this resembles a Chai Hu Tang syndrome, due to interior deficiency and sluggish lower jiao qi causing difficult urination, giving Chai Hu Tang would further deplete fluids, leading to rectal heaviness. Vomiting not caused by drinking water: If it were a Chai Hu syndrome. If vomiting is caused by drinking water, it indicates water retention in the epigastrium. The *Jin Gui Yao Lue* states: Thirst followed by vomiting indicates water retention in the epigastrium, belonging to Phlegm-Fluid disorders. Drinking water leads to vomiting due to retention; eating food leads to hiccups due to accumulation. Neither is suitable for Xiao Chai Hu Tang. Both are contraindications for Chai Hu Tang and must be recognized.
In Cold Damage, on the fourth or fifth day, with body heat, aversion to wind, neck stiffness, hypochondriac fullness, warm hands and feet, and thirst, Xiao Chai Hu Tang governs.
The previous section discussed the error of using purgatives when Chai Hu was indicated, leading to complications like hypochondriac pain, neck stiffness, and urinary difficulty. If the original disease presented with neck stiffness and hypochondriac fullness, Chai Hu Tang is indeed appropriate, contrary to the erroneous case described. Thus, it is reiterated.
Body heat, aversion to wind, and neck stiffness indicate unresolved exterior pathogens. Hypochondriac fullness and thirst indicate interior disharmony. Pathogens at the exterior typically cause hot hands/feet; pathogens at the interior cause cold hands/feet. Warm hands/feet indicate pathogens between exterior and interior. Administer Xiao Chai Hu Tang to resolve exterior and interior pathogens.
In Cold Damage, with a superficial pulse that is choppy and a deep pulse that is string-taut, and according to principle, acute abdominal pain should occur. First administer Xiao Jian Zhong Tang (Minor Construct the Middle Decoction). If not relieved, administer Xiao Chai Hu Tang.
With a superficial choppy and deep string-taut pulse, accompanied by acute abdominal pain, treat as interior deficiency-cold with Xiao Jian Zhong Tang to warm the middle and dispel cold. If not relieved, it is not interior cold, but rather pathogens transmitting from exterior to interior causing interior qi obstruction. Administer Xiao Chai Hu Tang, removing Huang Qin and adding Bai Shao to clear transmitted interior pathogens.