背为阳，腹为阴。背恶寒，阳不足也。阳不足，则阴气盛。阴气盛者，口中和。阳气内陷者，
口干燥，附子、白虎宜加详审。
口中和，背恶寒者，属少阴，附子汤及灸气海。阳气内陷，口干燥，背恶寒，白虎汤。
寒热往来者，阴阳相胜，邪正相争而作也。盖阳不足，则阴邪出于表而与之争，
故阴胜而为寒。阴不足，则阳邪入于里而与之争，故阳胜而为热。邪居表多，则多寒。邪居里多，
则多热。邪在半表半里，则寒热相半，乍往乍来而间作也。小柴胡汤专主寒热，寒多者，加桂；热
多者，加大黄，是大法也。
太阳病八九日，如疟状，发热恶寒，热多寒少，不呕，清便自可，一日二三度发，桂枝麻黄各
半汤；脉微缓者，不可汗，宜越婢汤。
病至十余日，热结在里，往来寒热，大柴胡汤。心烦发呕，胸膈满，不欲食，寒热往来，小柴胡
汤。
汗下后不呕不渴，头汗出，胸膈满，小便不利，寒热往来，柴胡桂姜汤。
热多寒少，尺脉迟者，荣血不足，黄 建中汤。脉浮大，寒热往来，宜祛邪。
凡妇人中风七八日，续得寒热，发作有时，经水适断，为热入血室，小柴胡汤。
潮热，属阳明，阳明旺于未申，一日一发，日晡而作也。邪入胃腑，为可下之证。设或脉浮而
紧，潮热而利，或小便难，大便溏者，热未入腑，犹带表邪，先当
和解其外。如小便利，大便硬，方可攻之。若潮热于寅卯，寅卯则属少阳，潮于巳午，则属太阳，
是又不可不辩。
病患烦热，汗出则解，又如疟状，日晡潮热，脉实，可下，小承气汤或大柴胡；脉虚者，不可下，
桂枝汤。
阳明病，潮热，大便微硬者，大承气汤。阳明病，脉浮而紧，必潮热，发作有时，但脉浮者，必
盗汗出，柴胡桂枝汤。
腹满，不大便，潮热，小承气汤微利之。
The back belongs to Yang, and the abdomen belongs to Yin. Cold intolerance of the back indicates insufficiency of Yang Qi. When Yang Qi is insufficient, Yin Qi becomes excessive. In cases of excessive Yin Qi, the mouth feels harmonious (neither bitter nor dry). In cases where Yang Qi has sunk inward, the mouth and tongue are dry; in such instances, careful examination is required before administering Fuzi Tang (Aconite Decoction) or Baihu Tang (White Tiger Decoction).
Cases with a harmonious mouth sensation and cold intolerance of the back belong to Shaoyin Disease. The appropriate treatment is Fuzi Tang, and moxibustion may be applied to Qihai (CV6). For cases where Yang Qi has sunk inward, presenting with a dry mouth and cold intolerance of the back, Baihu Tang is indicated.
Alternating chills and fever (Huanre Wanglai) arise from the mutual victory and defeat of Yin and Yang, and the struggle between pathogenic factors and healthy Qi. Generally, when Yang Qi is insufficient, Yin pathogens emerge at the exterior and contend with healthy Qi, resulting in Yin excess manifesting as chills. When Yin Qi is insufficient, Yang pathogens enter the interior and contend with healthy Qi, resulting in Yang excess manifesting as fever. If pathogens reside mostly at the exterior, chills predominate; if they reside mostly in the interior, fever predominates. If pathogens reside in the half-exterior and half-interior region, chills and fever are equal, occurring intermittently with alternating onset. Xiaochaihu Tang (Minor Bupleurum Decoction) specifically treats alternating chills and fever. If chills predominate, add Guizhi (Cinnamon Twig); if fever predominates, add Dahuang (Rhubarb Root and Rhizome). This constitutes the fundamental principle.
In Taiyang Disease persisting for eight or nine days, symptoms resembling malaria occur: fever and chills, with more fever than chills, no vomiting, normal bowel movements, and episodes occurring two or three times a day. Guizhi Mahuang Ge Ban Tang (Guizhi and Mahuang Combined Half-Dose Decoction) is indicated. If the pulse is slightly slow and relaxed, sweating should not be induced; Yuebi Tang (Yuebi Decoction) is appropriate.
After ten-plus days of illness, if heat is consolidated within the interior accompanied by alternating chills and fever, Da Chaihu Tang (Major Bupleurum Decoction) is indicated. If there is mental restlessness, vomiting, fullness in the chest and diaphragm, anorexia, and alternating chills and fever, Xiaochaihu Tang is indicated.
After perspiration or purgation therapy, if there is no vomiting or thirst, but only sweating on the head, fullness in the chest and diaphragm, dysuria, and alternating chills and fever, Chaihu Guijiang Tang (Bupleurum, Coptis, and Ginger Decoction) is indicated.
If fever predominates over chills and the Chi pulse (distal radial pulse) is slow, this indicates deficiency of Ying Blood (Nutritive Blood). Huangqi Jianzhong Tang (Astragalus Decoctio ad Construing the Middle Jiao) is indicated. If the pulse is floating and large with alternating chills and fever, expelling pathogens is appropriate.
For women suffering from Wind Strike for seven or eight days who subsequently develop alternating chills and fever at regular intervals, coinciding with the sudden cessation of menstruation, this is termed Heat entering the Blood Chamber (Xueshi). Xiaochaihu Tang is indicated.
Tidal Fever (Chaore) belongs to Yangming Disease. Yangming Qi flourishes during the Wei and Shen hours (13:00–17:00). Tidal fever occurs once daily, typically manifesting during the Ribu period (15:00–17:00). Pathogens entering the stomach fu-organ constitute an indication for purgation. However, if the pulse is floating and tight, accompanied by tidal fever and diarrhea, or difficult urination and loose stools, the heat has not fully entered the fu-organ and still carries exterior pathogens; reconciliation of the exterior should be performed first. If urination is clear and stool is hard, purgation may then be administered. If tidal fever occurs during the Yin and Mao hours (03:00–07:00), it relates to the Shaoyang Channel; if it occurs during the Si and Wu hours (09:00–13:00), it relates to the Taiyang Channel. These distinctions must not be overlooked.
If a patient experiences irritability and heat, which resolve after sweating, yet resembles malaria with tidal fever at Ribu time and a solid pulse, purgation is permissible using Xiao Chengqi Tang (Minor Order the Qi Decoction) or Da Chaihu Tang. If the pulse is deficient, purgation is contraindicated; Guizhi Tang is indicated.
In Yangming Disease, if tidal fever is present and the stool is slightly hard, Da Chengqi Tang (Major Order the Qi Decoction) is indicated. In Yangming Disease, if the pulse is floating and tight, tidal fever will inevitably occur at regular intervals. If the pulse is merely floating, night sweats (Daohan) will inevitably occur; Chaihu Guizhi Tang (Bupleurum and Cinnamon Twig Decoction) is indicated.
If abdominal fullness, constipation, and tidal fever are present, Xiao Chengqi Tang should be used to mildly promote bowel movement.