太阳病，项背强KT KT 、无汗、恶风者，葛根汤主之。
太阳病，项背强KT KT 而汗出恶风者，桂枝加葛根汤主之。
足太阳脉自络脑而还出下项，挟背脊。此从风池而入，不上干于脑，而下行于背，故头不痛而项背强也。
KTKT ，项背牵动之象，动中见有强意。凡风伤卫分，则皮毛闭，故无汗；风伤营分，则血动摇，故汗
自出。不可以本症之无汗为伤寒，他条之自汗出为中风也。桂枝大青龙症，恶风兼恶寒者，是中冬月之阴风。此
恶风不恶寒者，是感三时鼓动之阳风。风胜而无寒，故君葛根之甘凉，减桂枝之辛热，大变麻、桂二汤温散之法。
《内经》云“东风生于春。病在肝，俞在头项；中央为土，病在脾，俞在脊。”又“秋气者，病在肩背。”
则知颈项强，不属冬月之寒风。《易》以“艮”为山，又以“艮”为背。山主静，人以背应之。故元首四肢俱主
动，而背独主静。葛根禀气轻清，而赋体浓重。此不惟取其轻以去实，复取其重以镇动也。此又培土宁风之法。
太阳与阳明合病，必自下利，葛根汤主之。
不言两经相合何等病，但举下利而言，是病偏于阳明矣。太阳主表，则不合下利。下利而曰“必”，必阳并
于表、表实而里虚耳。葛根为阳明经药，惟表实里虚者宜之。而胃家实非所宜也，故仲景于阳明经中反不用葛根。
若谓其能亡津液而不用，则与本草生津之义背矣。若谓其能大开肌肉，何反加于汗出恶风之合病乎？有汗无汗，
下利不下利，俱得以葛根主之。是葛根与桂枝同为解肌和中之剂，与麻黄之专于发表不同。
太阳与阳明合病，不下利，但呕者，葛根加半夏汤主之。
太阳阳明合病，太阳少阳合病，阳明少阳合病，必自下利，则下利似乎合病当然之症。今不下利而呕，又似
乎与少阳合病矣。于葛根汤加半夏，兼解少阳半里之邪，便不得为三阳合病。
葛根汤∶
葛根（四两） 麻黄（二两） 生姜（三两） 桂枝（二两） 芍药（二两） 甘草（一两） 大枣（十枚）
水一斗，先煮麻黄、葛根，减二升，去沫，内诸药，煮取三升，温服一升，覆取微似汗，不须啜粥。余如桂枝法。
轻可以去实，麻黄、葛根是也。去沫者，止取其清阳发腠理之义也。葛根能佐麻黄而发表，佐桂枝以解肌。
不须啜粥者，开其腠理而汗自出，凉其肌肉而汗自止。是凉散以驱风，不必温中以逐邪矣。
桂枝加葛根汤∶
本方加葛根（四两）。旧本有麻黄者误。
葛根加半夏汤∶
本方加半夏（半升）。
Taiyang disease (disease of the Taiyang/Bladder channel), characterized by stiffness and tension in the nape and back, absence of sweating, and aversion to wind, is primarily treated with Gegen Tang (Kudzu Decoction).
Taiyang disease (disease of the Taiyang/Bladder channel), characterized by stiffness and tension in the nape and back accompanied by spontaneous sweating and aversion to wind, is primarily treated with Guizhi Jia Gegen Tang (Cinnamon Twig Decoction plus Kudzu Root).
The Foot-Taiyang Bladder meridian connects with the brain, returns, descends through the nape, and runs alongside the spinal column. When pathogenic factors enter via the Fengchi (GB20) acupoint without ascending to disturb the head but descending to affect the back, headache is absent, resulting primarily in stiffness and tension in the nape and back.
"Ji Ji" (a term describing stiffness/tension), represents the sensation of pulling and trembling in the nape and back, indicating rigidity within movement. When Wind pathogen damages the Wei (Defensive) level, the skin pores close, leading to an absence of sweat; when it damages the Ying (Nutritive) level, blood becomes agitated, leading to spontaneous sweating. One cannot classify the former as Cold Damage (Shanghan) solely due to the absence of sweat, nor the latter as Wind Strike (Zhongfeng) solely due to the presence of spontaneous sweating. In cases of Guizhi Tang syndrome or Da Qing Long Tang syndrome, where aversion to wind is combined with aversion to cold, it indicates exposure to Yin-wind of winter. Here, only aversion to wind without aversion to cold indicates exposure to Yang-wind that stirs during the three seasons (spring, summer, autumn). Since Wind is predominant and Cold is absent, Ganliang (Sweet and Cool) Gegen (Puerariae Radix) is used as the sovereign herb, reducing the Xinre (Acrid and Hot) nature of Guizhi (Cinnamomi Ramulus), thereby fundamentally altering the warm-dispersing methods of Mahuang Tang (Ephedra Decoction) and Guizhi Tang (Cinnamon Twig Decoction).
The *Neijing* states: "East wind arises in spring; disease occurs in the Liver, and its Shu points are located at the head and nape; the center belongs to Earth; disease occurs in the Spleen, and its Shu points are located at the spine." It also states: "Autumn qi causes disease in the shoulders and back." Thus, it is known that neck and back stiffness does not belong to the cold wind of winter. The *I Ching* uses the trigram Gen (Mountain) to symbolize the mountain and also the back. Mountains represent stillness, and the human back corresponds to this. Therefore, the head and four limbs are associated with movement, while the back alone is associated with stillness. Gegen (Puerariae Radix) possesses a light and clear Qi but a dense and heavy physical form. This allows one not only to use its lightness to dispel excess but also its heaviness to calm agitation. This is another method of strengthening Earth (Spleen/Stomach) to pacify Wind.
When Taiyang and Yangming channels combine, spontaneous diarrhea inevitably occurs, which is treated with Gegen Tang (Kudzu Decoction).
The text does not specify the exact nature of the combination between the two channels but mentions diarrhea, indicating the pathology leans toward the Yangming channel. Taiyang governs the exterior and typically does not cause diarrhea. The certainty of diarrhea ("bi") implies that Yang Qi merges with the exterior, causing exterior excess and interior deficiency. Gegen (Puerariae Radix) is a herb for the Yangming channel, suitable only for cases of exterior excess and interior deficiency, and not for Stomach-Excess patterns. Hence, Zhang Zhongjing rarely uses Gegen in Yangming channel diseases. If one argues it is avoided because it consumes body fluids, this contradicts the materia medica description of Gegen generating fluids. If one argues it opens muscle layers excessively, why is it added to combinations involving sweating and aversion to wind? Whether there is sweat or not, whether there is diarrhea or not, Gegen can be used as the primary agent. This shows that Gegen, like Guizhi (Cinnamomi Ramulus), is a muscle-relaxing and middle-jiao-harmonizing agent, distinct from Mahuang (Ephedrae Herba) which specializes in releasing the exterior.
When Taiyang and Yangming channels combine, without diarrhea but with vomiting, Gegen Jia Banxia Tang (Kudzu Decoction plus Pinellia) is primarily used.
In combinations of Taiyang-Yangming, Taiyang-Shaoyang, or Yangming-Shaoyang, spontaneous diarrhea seems to be a standard symptom. Now, the absence of diarrhea but presence of vomiting seems akin to a Shaoyang combination. Adding Banxia (Pinelliae Rhizoma) to Gegen Tang (Kudzu Decoction) helps resolve pathogens in the half-interior of Shaoyang, thus preventing it from being classified as a Three-Yang combination.
Gegen Tang (Kudzu Decoction):
Gegen (Puerariae Radix) (4 liang), Mahuang (Ephedrae Herba) (2 liang), Shengjiang (Zingiberis Rhizoma Recens) (3 liang), Guizhi (Cinnamomi Ramulus) (2 liang), Shaoyao (Paeoniae Radix Alba) (2 liang), Gancao (Glycyrrhizae Radix et Rhizoma) (1 liang), Dazao (Ziziphi Jujubae Fructus) (10 pieces).
Use 10 dou of water. First decoct Mahuang (Ephedrae Herba) and Gegen (Puerariae Radix), reduce volume by 2 dou, remove foam, then add remaining herbs. Decoct to obtain 3 sheng. Take 1 sheng warm. Cover to induce slight sweating. No need to drink hot porridge. Other care follows Guizhi Tang (Cinnamon Twig Decoction) protocol.
Light substances can dispel excess; Mahuang (Ephedrae Herba) and Gegen (Puerariae Radix) are examples. Removing the foam retains only the meaning of clearing Yang Qi to open the cou-li (skin pores). Gegen (Puerariae Radix) assists Mahuang (Ephedrae Herba) in releasing the exterior and assists Guizhi (Cinnamomi Ramulus) in resolving the muscles.
No need to drink hot porridge because opening the cou-li leads to natural sweating, and cooling the muscles stops sweating. This is using cool dispersal to drive out Wind, eliminating the need to warm the middle to expel pathogens.
Guizhi Jia Gegen Tang (Cinnamon Twig Decoction plus Kudzu Root):
Add Gegen (Puerariae Radix) (4 liang) to the base formula. Older editions containing Mahuang (Ephedrae Herba) are erroneous.
Gegen Jia Banxia Tang (Kudzu Decoction plus Pinellia):
Add Banxia (Pinelliae Rhizoma) (half sheng) to the base formula.