太阳病惟寒伤营者无汗。此外若风湿暑热之邪。初起即令汗自出。至一入阳明。即寒伤
营者
。其始发热无汗。至此亦 然汗出。而不恶寒反恶热矣。此之自汗。皆不得以表虚论治也。
有邪在于表。汗出不彻。应须再汗而愈者。经云。病常自汗出者。此为荣气和。荣气和
者外不谐
。以卫气不共营气和谐故尔。以荣行脉中。卫行脉外。复发其汗。荣卫和则愈。宜桂枝汤。
又曰。病患脏无他病。时发热自汗出而不愈者。此卫气不和也。先其时发汗则愈。宜桂枝汤
。盖麻黄乃发汗之峻剂。惟无汗者宜之。桂枝则于发汗之中。仍寓固卫之气。故汗出而复发
其汗者。不取麻黄而取桂枝也。
经云。酒客病不可与桂枝汤。以酒客不喜甘故也。盖酒气与谷气相并。其中必热。故不
可与桂枝。以其人湿热重故也。酒客如此。则凡病之因暑湿而起者。其不宜桂枝更明矣。
其有因里实而汗自出者。经云。阳明病其人多汗。以津液外出。胃中燥。大便必硬。硬
则谵
语。小承气汤主之。又云。阳明病发热汗多者。急下之。宜大承气汤。盖里气既通。则邪热
下行而汗自止矣。
又有汗多亡津液。而邪犹在于经。未入于府者经云。服桂枝汤。大汗出后。大烦渴不解
。脉
洪大者。白虎加人参汤主之。盖必急救其阴。则烦渴除而汗亦止矣。更有汗多亡阳者。经云
。太阳病发汗。遂漏不止。其人恶风。小便难。四支微急。难以屈伸者。桂枝加附子汤主之
。又云。发汗病不解。反恶寒者。虚故也。芍药甘草附子汤主之。盖必以附子合芍药以温经
固卫。则阳回而汗自 。则同一汗出。而虚实寒热。治又不同矣。
阴病不得有汗。其有汗出如油。喘而不休。以及伤寒六七日不利便。发热而利。其人汗
出不
止者。皆死病也。其间有可治者。如经云。下利清谷。里寒外热。汗出而厥者。通脉四逆汤
主之。既吐且利。小便复利而大汗出。下利清谷。内寒外热。脉微欲绝者。四逆汤主之。又
吐已下断。汗出而厥。四支拘急不解。脉微欲绝者。通脉四逆汤主之。此皆急温之证。不可
须臾缓也。
太阳病中，只有寒邪损伤营分的情况才无汗。除此之外，如果是风湿、暑热等邪气，初起时就会让汗液自行流出。一旦进入阳明经，即使是寒邪伤营的病症，开始虽然发热无汗，到了这个阶段也会变成自然出汗，并且不再怕冷反而怕热了。这种自汗，都不能按照表虚证来治疗。
有邪气停留在体表，导致出汗不彻底，需要再次发汗才能痊愈的情况，《伤寒论》说：病人经常自汗出，这是因为营气调和。营气调和而外在不协调，是因为卫气不能与营气和谐配合的缘故。因为营气行于脉中，卫气行于脉外，所以再次发汗，使营卫和谐就能痊愈，适宜用桂枝汤。
又说：病人脏腑没有其他疾病，时常发热并自汗出但不能痊愈的，这是卫气不和。在发热出汗之前进行发汗处理就能痊愈，适宜用桂枝汤。大概麻黄是发汗的峻猛药剂，只适合无汗的人使用。桂枝则在发汗之中，仍蕴含固护卫气的作用，所以对于已经出汗而又需要再次发汗的情况，不选用麻黄而选用桂枝。
《伤寒论》说：喝酒的人患病不可给予桂枝汤，因为喝酒的人不喜欢甘甜的味道。酒气与谷气相结合，体内必然产生热邪，所以不可用桂枝，因为这类人体内湿热较重。喝酒的人是这样，那么凡是因暑湿引起的疾病，不宜使用桂枝就更明显了。
其中有因为里实（肠道积滞）而导致汗自出的情况，《伤寒论》说：阳明病患者多汗，因为津液向外流失，胃中干燥，大便必定坚硬。大便坚硬就会出现谵语（神志不清，胡言乱语），用小承气汤主治。又说：阳明病发热且汗多的，应当紧急攻下，适宜用大承气汤。大概里气通畅后，邪热下行，汗自然就停止了。
又有出汗过多导致津液亏损，但邪气仍在经络，未进入腑脏的情况。《伤寒论》说：服用桂枝汤后，大汗出之后，出现严重烦躁口渴不解，脉象洪大的，用白虎加人参汤主治。大概必须急救阴液，那么烦躁口渴消除，汗也就止住了。更有出汗过多导致亡阳的情况，《伤寒论》说：太阳病发汗后，汗漏出不止，病人怕风，小便困难，四肢轻微拘急，难以屈伸的，用桂枝加附子汤主治。又说：发汗后病未解除，反而恶寒的，是因为虚损，用芍药甘草附子汤主治。大概必须用附子配合芍药来温通经脉、固护卫气，阳气回复，汗自然停止。同样是出汗，但虚实寒热的病机不同，治疗方法也不同。
阴证通常不会有汗。如果有汗出如油，气喘不停，以及伤寒六七天不大便也不拉肚子，却发热并伴有腹泻，病人汗出不止的，都是死证。其中也有可治的情况，如《伤寒论》说：下利排出未消化的食物，内寒外热，出汗且四肢厥冷的，用通脉四逆汤主治。既呕吐又腹泻，小便反而通利且大汗出，下利排出未消化的食物，内寒外热，脉微细几乎摸不到的，用四逆汤主治。又呕吐已止，腹泻也断绝，但出汗且四肢厥冷，四肢拘急不缓解，脉微细几乎摸不到的，用通脉四逆汤主治。这些都是急需温补的证候，一刻也不能拖延。
In Taiyang disease (Taiyang Syndrome), only cases where cold pathogen damages the Ying (Nutritive) Qi present with anhidrosis. In other instances, if the pathogen is wind-dampness, summerheat, or heat, spontaneous sweating occurs from the onset. Once the disease enters the Yangming stage, even in cases initially caused by cold damaging the Ying Qi, which started with fever and anhidrosis, it transitions to spontaneous sweating, accompanied by aversion to heat rather than aversion to cold. Such spontaneous sweating should not be treated as Exterior Deficiency syndrome.
There are cases where pathogens remain at the exterior, causing incomplete sweating, requiring a second diaphoretic treatment for recovery. The Classic states: "When a patient constantly sweats spontaneously, this indicates that the Ying Qi is harmonious. Although the Ying Qi is harmonious, there is disharmony on the exterior because the Wei (Defensive) Qi does not harmonize with the Ying Qi. Since Ying Qi circulates within the vessels and Wei Qi circulates outside the vessels, inducing sweat again will restore harmony between Ying and Wei, leading to recovery. Guizhi Tang (Cinnamon Twig Decoction) is indicated."
It also states: "If a patient has no internal organ pathology but experiences intermittent fever and spontaneous sweating without recovery, this is due to disharmony of the Wei Qi. Inducing sweat prior to the onset of fever will lead to recovery. Guizhi Tang (Cinnamon Twig Decoction) is indicated." Generally, Mahuang Tang (Ephedra Decoction) is a potent diaphoretic agent suitable only for those with anhidrosis. Guizhi Tang (Cinnamon Twig Decoction), while inducing sweat, simultaneously possesses properties to secure the Wei Qi. Therefore, in cases of spontaneous sweating requiring further diaphoresis, Guizhi Tang is preferred over Mahuang Tang.
The Classic states: "Patients who consume alcohol should not be given Guizhi Tang (Cinnamon Twig Decoction) because they dislike sweet flavors. The qi of alcohol combines with grain qi, generating internal heat; thus, Guizhi Tang is contraindicated due to their heavy damp-heat constitution. If this applies to drinkers, it is even more evident that formulas involving Guizhi are unsuitable for diseases arising from summerheat-dampness."
In cases where spontaneous sweating results from interior excess (intestinal accumulation), the Classic states: "Yangming patients often sweat profusely. As fluids exit externally, the stomach becomes dry, and the stool becomes hard. Hardness leads to delirium (confused speech). Xiao Chengqi Tang (Minor Order the Yellow Decoction) is indicated." It further states: "In Yangming disease, if there is fever and profuse sweating, urgent purgation is required. Da Chengqi Tang (Major Order the Yellow Decoction) is indicated." Once the interior qi flows freely, the pathogenic heat descends, and sweating ceases naturally.
In cases where excessive sweating depletes body fluids, yet the pathogen remains in the meridians without entering the fu organs, the Classic states: "After taking Guizhi Tang (Cinnamon Twig Decoction), if profuse sweating occurs followed by severe restlessness and unquenchable thirst, with a surging pulse, Baihu Jia Renshen Tang (White Tiger Decoction plus Ginseng) is indicated." Urgent preservation of Yin fluids is necessary; once Yin is restored, restlessness and thirst subside, and sweating stops.
Furthermore, excessive sweating can lead to Yang collapse. The Classic states: "In Taiyang disease, after inducing sweat, if leakage continues incessantly, accompanied by aversion to wind, difficulty urinating, slight stiffness in the four limbs, and inability to flex or extend them, Guizhi Jia Fuzi Tang (Cinnamon Twig Decoction plus Aconite Root) is indicated." It also states: "If after inducing sweat the disease persists and aversion to cold worsens, it indicates deficiency. Shaoyao Gancao Fuzi Tang (Peony and Licorice Decoction plus Aconite Root) is indicated." Combining Fuzi (Aconite Root) with Shaoyao (Peony Root) warms the meridians and secures the Wei Qi, restoring Yang and stopping sweating. Thus, although the symptom is sweating, the treatments differ based on deficiency/excess and cold/heat patterns.
Yin syndromes typically do not present with sweating. However, sweating like oil, continuous panting, or in the case of Cold Damage lasting six to seven days without constipation or diarrhea, presenting with fever and diarrhea accompanied by incessant sweating, are all fatal signs. Among these, some are treatable. The Classic states: "In dysentery with undigested food, interior cold with exterior heat, sweating, and cold extremities, Tongmai Sini Tang (Pulse-Recovering Counterflow Cold Decoction) is indicated." If vomiting and diarrhea occur together, with free urination, profuse sweating, dysentery with undigested food, interior cold with exterior heat, and a faint pulse nearly imperceptible, Sini Tang (Counterflow Cold Decoction) is indicated. If vomiting and diarrhea cease, but sweating and cold extremities persist, along with limb stiffness and a faint pulse nearly imperceptible, Tongmai Sini Tang (Pulse-Recovering Counterflow Cold Decoction) is indicated. These are critical conditions requiring urgent warming therapy without delay.