潮热者。不恶寒。但恶热。其来如潮之至。不失其时。谓之潮热。其证属里而不属表。
凡恶
寒发热属太阳。至少阳则往来寒热。此之潮热则属阳明。往往发于日晡。日晡未申之时。阳
明居中土。王于未申。邪入中土。无所复传。
故郁为实热。随王而潮。经云。日晡所发潮热者。属阳明也。惟其属阳明。则胃实为可
下之证。故曰潮热者实也。
潮热固可下而下法要有次第。经云。太阳病三日。发汗不解。蒸蒸发热者属胃也。调胃
承气
汤主之。此因胃已实而热未潮。故但用调胃承气。微利之而已。又云。阳明病脉迟。虽汗出
不恶寒者。其身必重。短气腹满而喘。有潮热者。此外欲解可攻里也。手足
然汗出者。此大便已硬也。大承气汤主之。若汗多微发热恶寒者。外未解也。其热不潮。未
可与承气汤。若腹大满不通者。可与小承气汤。微和胃气。勿令大泄下。按三承气俱用大黄
。大承气重用枳朴。兼以芒硝。上承邪热而下。用以攻坚破结。荡涤肠胃。乃峻下之剂。小
承气去芒硝而轻用枳朴。止取通利肠胃。其下较轻。调胃承气。佐以甘草。又于下中兼和。
三承气各有所主。仲景下法。不敢妄施。其慎细如此。又云。太阳病。重发汗而复下之。舌
上燥而渴。日晡小有潮热。从心下至少腹。硬满而痛不可近者。大陷胸汤主之。夫病至心下
及少腹硬满而痛不可近。则势已剧甚。此又非大承气所能胜任。宜兼破胸膈之结。以下通于
肠胃。则必主以大陷胸汤而无疑矣。
其有
阳明病潮热未去。而已趋入少阳者。经云。阳明病。发潮热。大便溏。小便自可。胸胁满不
去者。小柴胡汤主之。此非小柴胡汤之能治潮热也。胸胁满不去。已具少阳证。且大便已溏
。虽潮热未罢。未可再攻也。
更有瘅疟者。但热不寒。发作有时。此亦阳明经热。其热止在于经。未入于府。且病不从
伤寒来。故名之曰瘅疟。仲景不立方。而但曰以饮食消息之。
要之甘寒彻热。与治阳明经热同法也。
Tidal fever refers to a condition where there is no aversion to cold, only aversion to heat. Its onset occurs like the tide, arriving at regular intervals without missing its time, hence it is called tidal fever. This syndrome belongs to the interior (Li) and does not belong to the exterior (Biao).
Generally, aversion to cold accompanied by fever belongs to Taiyang disease; when it reaches Shaoyang, it presents as alternating chills and fever. However, this type of tidal fever belongs to Yangming disease. It often occurs during the "Ribuxia" period (Shen hour, 3:00 PM to 5:00 PM). Since the Yangming meridian governs the central Earth element and is prosperous during the Wei (1:00 PM to 3:00 PM) and Shen hours, pathogenic factors entering the central Earth have nowhere else to transmit. Consequently, they stagnate and transform into excess heat, surging like the tide in accordance with the prosperity of the meridian qi. The Classic states: "Tidal fever occurring at Ribuxia belongs to Yangming." Because it belongs to Yangming, stomach excess (Wei Shi) is an indication for purgation, hence it is said that "tidal fever indicates excess."
Although tidal fever can be treated with purgation, the method must follow a sequence. The Classic states: "In Taiyang disease, after three days, if sweating fails to resolve the condition and steaming-hot fever appears, it belongs to the Stomach; Tiaowei Chengqi Tang should be used." This is because the Stomach is already full/excess but the heat has not yet formed tidal patterns, so only Tiaowei Chengqi Tang is used to mildly promote bowel movement. It also states: "In Yangming disease, if the pulse is slow, although there is sweating and no aversion to cold, the body will feel heavy, with shortness of breath, abdominal fullness, and wheezing. If there is tidal fever, it indicates that the exterior has resolved and the interior can be attacked. If sweat oozes continuously from the hands and feet, it indicates that the feces have hardened; Dachengqi Tang should be used. If there is much sweating with slight fever and aversion to cold, the exterior has not resolved. If the heat is not tidal, Chengqi Tang should not be given. If the abdomen is severely full and obstructed, Xiao Chengqi Tang may be given to mildly harmonize the Stomach Qi, avoiding severe purgation."
All three Chengqi Decoctions use Rhubarb (Dahuang). Dachengqi Tang heavily uses Immature Bitter Orange (Zhishi) and Magnolia Bark (Houpo), combined with Mirabilite (Mangxiao), to carry pathogenic heat downward, breaking hard accumulations and clearing the intestines and stomach; it is a harsh purgative. Xiao Chengqi Tang removes Mirabilite and uses lighter doses of Immature Bitter Orange and Magnolia Bark, aiming only to facilitate intestinal movement, thus having a milder purgative effect. Tiaowei Chengqi Tang adds Licorice Root (Ganzcao) to harmonize while purging. Each of the three Chengqi Decoctions has its specific indications. Zhang Zhongjing did not dare to apply purgation recklessly, showing such caution and detail.
It also states: "In Taiyang disease, if excessive sweating is followed by mistaken purgation, leading to dryness and thirst on the tongue, slight tidal fever at Ribuxia, and hardness, fullness, and pain from the epigastrium down to the hypogastrium that cannot be touched, Daxiexiong Tang should be used." When the disease progresses to hardness, fullness, and pain in the epigastrium and hypogastrium that cannot be tolerated to touch, the condition is severe. This exceeds the capacity of Dachengqi Tang; one must break the knot in the chest and diaphragm to connect downwards to the intestines and stomach, making the use of Daxiexiong Tang unquestionable.
There are cases where Yangming tidal fever persists while the pathology trends toward Shaoyang. The Classic states: "In Yangming disease, if there is tidal fever, loose stools, normal urination, and persistent fullness in the chest and hypochondrium, Xiaochaihu Tang should be used." This does not mean Xiaochaihu Tang treats tidal fever directly; rather, the persistent chest and hypochondriac fullness indicates Shaoyang syndrome. Furthermore, since the stools are already loose, even if tidal fever persists, further purgation is contraindicated.
Additionally, there is Dan Nue (Hot Malaria), characterized by fever without chills and regular paroxysms. This is also heat in the Yangming meridian. The heat remains only in the meridian and has not entered the fu organs. Moreover, it does not originate from Cold Damage transmission, hence it is named Dan Nue. Zhang Zhongjing provided no specific formula but stated that it should be managed through dietary adjustments.
In summary, the method of using sweet-cold herbs to clear heat is the same as treating Yangming meridian heat.