脉虚身热，得之伤暑；脉盛身寒，得之伤寒。盖寒伤形而不伤气，所以脉盛；热伤气而
不伤形，所以脉虚。（《甲乙经》）
中暑与热证相似，但热证脉盛，中暑者脉虚，以此别之耳。
脉浮自汗，或浮大而散，或洪大无力，或虚而迟中得洪缓，皆为伤暑之脉也。
太阳中 者，发热恶寒，身重疼痛，其脉弦细芤迟，小便利，洒洒然毛耸，手足逆
冷，少有劳，身即热，口开，口扳，齿燥。若发汗则恶寒甚，加温针，发热甚，数下之
则淋甚。（ 即暑也。）
太阳中热者， 是也。其人汗出，身热而 。白虎加人参汤主之。（《活人书》谓∶
自汗，恶寒，身热而渴，面垢，手足冷，脉微弱无力者，中 也。宜人参白虎汤。）
太阳中 者，身热疼重而脉微弱。此亦夏月伤冷水，水行皮中所致也。一物瓜蒂散
主之。
丹溪云∶夏火大热，损伤肺金，壮火食气，病暑者，多是不足之证。所以用清暑益
气汤、人参白虎汤、孙真人生脉散之类。足可以审前圣立方之旨矣。
丹溪有夏月伏阴在内之论。谓人与天地同一橐龠，天地之气升亦升，降亦降，浮亦
浮，沉亦沉。子月一阳生，寅月三阳生，此气之升也，人之气亦生也。巳月六阳生，阳尽
出于地上矣，此气之浮也。人之腹属地气，于此时亦浮于肌表，散于皮毛，腹中之阳亦虚
矣。故夏至后，六阳外泄，伏阴在内，此阴字有虚之义。若作虚冷者，其误甚矣。前人
治暑用大顺散、桂苓丸等剂，盖因凉亭、水阁、水泉、瓜果之伤，故不曰病热而曰病暑，
不用辛热，病何由安？非为伏阴在内而用之也，火令之时，流金烁石，何阴冷之有？世人
不察，妄谓伏阴，而
用温热，为世通弊。若谓夏月伏阴在内，宜服温热剂，则冬月阳在内，宜服寒凉。然则孟子
冬日饮汤、夏日饮水，亦不足信欤？
A deficient pulse accompanied by fever indicates injury from summerheat; a full pulse accompanied by coldness indicates injury from cold. This is because cold damages the form (physical structure) but not the Qi, hence the pulse is full; heat (summerheat) damages the Qi but not the form, hence the pulse is deficient. (*Jia Yi Jing*)
Heatstroke resembles heat syndromes, but in heat syndromes the pulse is full, whereas in heatstroke the pulse is deficient; this is how they are distinguished.
A floating pulse with spontaneous sweating, or a large and diffuse pulse, or a surging and forceless pulse, or a deficient and slow pulse with surging and moderate qualities, are all pulses indicating injury from summerheat.
Taiyang Zhong Yue (Summerheat Stroke in the Taiyang Channel) presents with fever, aversion to cold, heaviness and pain of the body, and a string-taut, thin, knotted, or slow pulse. Urination is clear and frequent, there is a sensation of chilliness as if wind were ruffling the hairs, and cold extremities. Slight exertion causes fever, open-mouth breathing, trismus (lockjaw), and dry teeth. If diaphoresis (sweating-inducing treatment) is used, aversion to cold worsens; if moxibustion/needling with heat is applied, fever intensifies; if purgatives are used repeatedly, strangury (painful urination) worsens. ("Zhong Yue" refers to summerheat stroke.)
Taiyang Zhong Re (Summerheat Heat in the Taiyang Channel) is Zhong Yue. The patient sweats, has fever, and thirst. Baihu Jia Renshen Tang (White Tiger Decoction plus Ginseng) is the primary formula. (*Huo Ren Shu* states: Spontaneous sweating, aversion to cold, fever, thirst, facial grease, cold extremities, and a weak, forceless pulse indicate Zhong Yue. Ren Shen Bai Hu Tang is appropriate.)
Taiyang Zhong Yue presents with fever, painful heaviness of the body, and a weak pulse. This is also caused by drinking cold water in summer, causing cold water qi to circulate within the skin. Yiwu Gaudi San (Single-Ingredient Melon Pedicle Powder) is the primary formula.
Zhu Danxi stated: The intense heat of summer fire damages Lung Metal; vigorous fire consumes Qi. Patients with summerheat disease mostly present with deficiency syndromes. Therefore, formulas such as Qingshu Yiqi Tang (Clear Summerheat and Boost Qi Decoction), Ren Shen Bai Hu Tang (Ginseng White Tiger Decoction), and Sun Simiao's Rensheng Mai San (Ginseng and Pulse-Generating Powder) are used. These suffice to clarify the intent of the ancient sages in establishing prescriptions.
Danxi proposed the theory of "latent Yin inside during summer." He argued that humans and Heaven-Earth share the same bellows (Qi dynamics). When Heaven-Earth Qi rises, it rises; when it descends, it descends; when it floats, it floats; when it sinks, it sinks. In the 11th lunar month, one Yang arises; in the 3rd month, three Yangs arise—this is the rising phase, and human Qi also generates. In the 4th month, six Yangs arise, and Yang Qi completely emerges above the ground—this is the floating phase. The human abdomen corresponds to Earth Qi; at this time, Yang also floats to the muscle surface and disperses into the hair and skin, making the Yang within the abdomen deficient. Thus, after the Summer Solstice, the Six Yangs leak outward, and Yin lies latent within. The character "Yin" here carries the meaning of "deficiency." To interpret it as cold-deficiency would be a grave error. Ancients used Dasun San (Great Smooth Powder) and Guiling Wan (Cassia and Poria Pill) for treating summerheat, likely because patients were injured by cool pavilions, water pavilions, springs, and fruits/vegetables. Hence, it was called "disease from summerheat" rather than "disease from heat," and acrid-warm herbs were not used, otherwise how could the illness heal? This was not due to "latent Yin inside." During the Fire season, metals flow and stones melt (extreme heat); where is there any Yin-cold? People fail to investigate carefully, wrongly assuming latent Yin, and use warm-hot remedies, which is a common malpractice. If one claims that latent Yin inside during summer warrants warm-hot tonics, then does Yang inside during winter warrant cold-cool purgatives? Would Mencius’s saying about drinking hot soup in winter and cold water in summer be unreliable?