2.恶寒表里阴阳辨, 发热有汗表为虚, 发热无汗表实证, 实以麻黄虚
桂枝. 无热恶寒发阴里, 桂枝加附颇相宜, 背寒口和阴附子, 口燥渴
阳白虎需.
【注】恶寒一证, 有表里, 阴阳之辨. 发热恶寒发于阳表也, 有汗宜
桂枝汤, 无汗宜麻黄汤. 无热恶寒发于阴里也, 有汗宜桂枝加附子汤,
无汗宜麻黄附子细辛汤. 背恶寒口和, 谓口中不燥而和也; 阴, 谓属
少阴也, 宜附子汤. 背恶寒口燥渴, 谓口中燥而汤也; 阳, 谓属阳明
也,宜白虎加人参汤.
【按】阴阳二经, 恶寒虽同, 其身有热无热则异也, 一则汗之, 一则
温之. 少阴、 阳明之背恶寒虽同, 其口中和、口中不和则异也, 一则
温之, 一则清之. 恶寒虽属轻微之证, 仲景立法可辨, 他可类推矣.
3.风寒相因相离少, 三阳俱有恶寒风, 恶风属阳法从表, 三阴恶寒
无恶风.
【注】风寒二者, 大率多相因而少相离, 有寒时不皆无风, 有风时不
皆无寒, 故三阳俱有恶寒恶风同见也. 恶风与恶寒均表病也 , 法当
从表; 然风属阳, 寒属阴, 故三阴经证有恶寒而无恶风也.
4.三阳头痛身皆热, 无热吐沫厥阴经, 不便尿红当议下, 尿白犹属
表未清.
【注】三阳, 谓太阳、阳明、少阳也. 头痛身皆热, 谓三阳头痛身皆
热也. 三阳经头痛, 法当从三阳治也. 厥阴头痛, 则多厥而无热, 呕
吐涎沫, 是厥阴挟寒邪上逆也, 宜吴茱萸汤温而降之. 三阳头痛, 若
不大便, 小便红赤, 为里实热, 法当议下, 宜承气汤. 若小便清白,
即不大便, 为里热未实, 表尚未清, 法当先从表治也. 三阴经无头痛
,惟厥阴有头痛, 以其脉与督脉上会于巅也. 三阴经无发热, 厥阴少
阴亦有发热, 谓之反发热, 以其脏有相火, 阴盛格阳于外也.
2. 辨别恶寒的表里与阴阳，发热且有汗属于表虚证，发热且无汗属于表实证；表实证用麻黄汤（Mahuang Tang, Ephedra Decoction），表虚证用桂枝汤（Guizhi Tang, Cinnamon Twig Decoction）。没有发热而仅感恶寒，病发于阴分里证，宜用桂枝加附子汤（Guizhi Jia Fuzi Tang, Cinnamon Twig Decoction plus Aconite Root）较为适宜。背部恶寒且口中平和（不燥），属少阴病（Shaoyin disease），宜用附子汤（Fuzi Tang, Aconite Root Decoction）；背部恶寒且口燥渴，属阳明病（Yangming disease），宜用白虎加人参汤（Baihu Jia Renshen Tang, White Tiger Decoction plus Ginseng Root）。
【注】恶寒这一症状，有表证与里证、阳证与阴证的鉴别。发热伴恶寒，病发于阳分表证，有汗者宜用桂枝汤，无汗者宜用麻黄汤。无发热而仅恶寒，病发于阴分里证，有汗者宜用桂枝加附子汤，无汗者宜用麻黄附子细辛汤（Mahuang Fuzi Xixin Tang, Ephedra, Aconite and Asarum Decoction）。背恶寒且口中平和，是指口中不干燥且感觉舒适；这里的“阴”，指属于少阴经，宜用附子汤。背恶寒且口燥渴，是指口中干燥；这里的“阳”，指属于阳明经，宜用白虎加人参汤。
【按语】少阴经与阳明经虽然都有恶寒，但区别在于身体是否有热；治疗上，前者宜温补，后者宜清热。少阴与阳明之背恶寒虽同，但区别在于口中是否平和；治疗上，前者宜温之，后者宜清之。恶寒虽属轻微症状，但张仲景（Zhang Zhongjing）确立的法则可以据此辨别，其他病症亦可类推。
3. 风寒往往相互伴随而很少分离，三阳经（Taiyang, Yangming, Shaoyang channels）均可见恶风与恶寒。恶风属阳，治法应从表解；三阴经（Jueyin, Taiyin, Shaoyin channels）恶寒则无恶风。
【注】风邪与寒邪，大多相互伴随而很少分离，有寒时不一定无风，有风时不一定无寒，所以三阳经常同时出现恶寒与恶风。恶风与恶寒均属表病，治法应当从表论治；然而风属阳邪，寒属阴邪，所以三阴经的病证只有恶寒而没有恶风。
4. 三阳经头痛身体皆发热，若无发热而呕吐涎沫，则为厥阴经（Jueyin channel）病；若大便不通、小便红赤当考虑使用下法（purging method），若小便清白则说明表邪未清。
【注】三阳，指太阳、阳明、少阳经。头痛且身体皆发热，是指三阳经头痛均伴有身热。三阳经头痛，治法应当从三阳经论治。厥阴经头痛，多表现为四肢厥冷而无发热，呕吐涎沫，这是厥阴经挟带寒邪上逆所致，宜用吴茱萸汤（Wuzhuyu Tang, Evodia Fruit Decoction）以温降之法治疗。三阳经头痛，若不大便，小便红赤，为里实热证，治法当考虑使用下法，宜用承气汤（Chengqi Tang, Bowel-Regulating Decoction）。若小便清白，即使不大便，也为里热尚未结实，表邪尚未清除，治法应当先从表证论治。三阴经一般无头痛，唯独厥阴经有头痛，因为其经脉与督脉（Du Mai, Governor Vessel）在巅顶交会。三阴经一般无发热，但厥阴经与少阴经也可出现发热，称为“反发热”（reverse fever），因其脏中有相火（ministerial fire），阴盛格拒阳气于外所致。
2. Differentiating Chills (Aversion to Cold) by Exterior/Interior and Yin/Yang: Fever with sweating indicates an Exterior Deficiency syndrome; fever without sweating indicates an Exterior Excess syndrome. For the Excess syndrome, use Mahuang Tang (Ephedra Decoction); for the Deficiency syndrome, use Guizhi Tang (Cinnamon Twig Decoction). Absence of fever with chills indicates a disease originating in the Interior Yin aspect; Guizhi Jia Fuzi Tang (Cinnamon Twig Decoction plus Aconite Root) is appropriate. Chills in the back with a harmonious mouth (no dryness) indicate Shaoyin disease (disease of the Lesser Yin), treated with Fuzi Tang (Aconite Root Decoction). Chills in the back with dry mouth and thirst indicate Yangming disease (disease of the Greater Yang), treated with Baihu Jia Renshen Tang (White Tiger Decoction plus Ginseng Root).
[Note] The symptom of chills requires differentiation between Exterior/Interior and Yin/Yang. Fever accompanied by chills originates from the Exterior Yang aspect; if there is sweating, Guizhi Tang is indicated; if there is no sweating, Mahuang Tang is indicated. Absence of fever with chills originates from the Interior Yin aspect; if there is sweating, Guizhi Jia Fuzi Tang is indicated; if there is no sweating, Mahuang Fuzi Xixin Tang (Ephedra, Aconite and Asarum Decoction) is indicated. "Back chills with a harmonious mouth" means the mouth is not dry and feels comfortable; "Yin" here refers to the Shaoyin channel, for which Fuzi Tang is suitable. "Back chills with dry mouth and thirst" means the mouth is dry; "Yang" here refers to the Yangming channel, for which Baihu Jia Renshen Tang is suitable.
[Commentary] Although both the Shaoyin and Yangming channels present with chills, they differ in whether the body has heat or not; one is treated by warming, the other by clearing heat. Although back chills are similar in Shaoyin and Yangming, they differ in whether the mouth is harmonious or not; one is treated by warming, the other by clearing. Although chills are a mild symptom, the principles established by Zhang Zhongjing allow for differentiation, and other conditions can be inferred by analogy.
3. Wind and Cold often accompany each other and rarely separate; all three Yang channels (Taiyang, Yangming, Shaoyang) may present with aversion to wind (Aversion to Drafts) and chills. Aversion to wind belongs to Yang and should be treated by releasing the exterior; aversion to cold in the three Yin channels (Jueyin, Taiyin, Shaoyin) does not include aversion to wind.
[Note] Wind pathogen and cold pathogen mostly accompany each other and rarely separate; when there is cold, there is not necessarily no wind, and when there is wind, there is not necessarily no cold. Therefore, the three Yang channels often present with both chills and aversion to wind together. Both aversion to wind and chills are exterior diseases, and the treatment principle is to address the exterior. However, wind belongs to Yang and cold belongs to Yin; thus, syndromes of the three Yin channels present with chills but not aversion to wind.
4. Headache in the three Yang channels is accompanied by whole-body heat; absence of heat with vomiting of saliva/phlegm indicates Jueyin channel disease. If there is constipation and red urine, purging methods should be considered; if the urine is clear and white, it indicates that the exterior pathogen has not yet been cleared.
[Note] "Three Yang" refers to the Taiyang, Yangming, and Shaoyang channels. "Headache with whole-body heat" refers to the fact that headaches in the three Yang channels are accompanied by systemic heat. Headaches in the three Yang channels should be treated according to the principles of the three Yang channels. Headache in the Jueyin channel is often accompanied by cold limbs (Jue) and absence of fever, along with vomiting of saliva/phlegm; this is due to cold pathogen counterflow in the Jueyin channel, and Wuzhuyu Tang (Evodia Fruit Decoction) should be used to warm and descend. In cases of headache in the three Yang channels, if there is constipation and red urine, it indicates interior excess-heat, and purging methods should be considered, using Chengqi Tang (Bowels-Regulating Decoction). If the urine is clear and white, even with constipation, it indicates that the interior heat is not yet solidified and the exterior pathogen has not been cleared; the treatment principle is to first address the exterior. Generally, the three Yin channels do not present with headache, except for the Jueyin channel, because its meridian intersects with the Du Mai (Governor Vessel) at the vertex. The three Yin channels generally do not present with fever, but Jueyin and Shaoyin channels may present with fever, termed "reverse fever," because the zang organs contain ministerial fire, and yin excess repels yang qi to the exterior.