经曰∶膏粱之变，足生大疔，受如持虚。膏粱浓味，热毒内积，其变多生大疽。其受毒部分
，则毒从虚处受之，大疔、大疽也，以其根深在内也。又曰∶荣气不从，逆于肉理，乃生痈肿。
夫疮疡之证，初成之时，当察经之传变，病之表里，人之虚实，受之浅深而攻补之。如肿病热渴
，大便闭结，邪在里也，疏通之。肿 赤痛，寒热头疼，邪在表也，发散之。 肿痛甚者，邪在
经络也，和解之。微肿微痛而不作脓者，气血虚也，补托之。漫肿不痛，或不作脓，或脓成不溃
者，气血虚甚也，峻补之。色黯而微觉肿痛，或脓成不出，或腐肉不溃者，阳气虚寒也，温补之
。若泥于未溃，而概用败毒之药，复损脾胃，不惟肿者亦不能成脓，而溃者也难收敛。七恶之候
蜂起，多致不救，此其大略而已。
痈疽之证有二十余种，最切要者，分别阴阳是也。发于阳者，属六腑，为表为火为实；发于
阴者，属五脏，为里为郁为虚。故阳发则大而高起，皮薄色赤，发有椒眼数十，轻按即痛，形大
而浅为痈。故阴发则平而内作，皮浓色淡，肿硬不起，状如顽肤，重按隐木而痛，形小而深为疽
。又有阳中之阴，似
热非热，虽肿而实虚。若赤而不躁，虽痛而无脓，即浮而复隐，外盛而内腐；其人多肥，肉紧而
内虚。有阴中之阳，似冷非冷，不肿而实，赤微而躁，有脓而痛，形虽不盛，而内实烦闷，其人
多瘦，肉缓而内实。有阳变为阴者，病发于阳而极热，则当顺气匀血。因有赤肿发热，便闭躁渴
之热证，脉洪数而实，虽严冬，惟当暂用苦寒之药以泻热毒。如过用寒凉，或误草药性冷，则气
滞血凝而危，急用温热药，使气行血和，乃可成脓。有阴变为阳者，病发于阴而极冷，则当内用
平补，兼以宣气滋血助阳，健脾进食。或不肿不赤，皮寒肢冷，泻利肠鸣，饮食不入，不时呕逆
等冷证，脉微弱而迟，虽盛暑，亦当暂用辛温之药以助阳气。倘又误凉药，急用大热之剂回阳，
不回者死。盖阳者，气也；阴者，血也。阴不足，阳有余。血涩气滞，荣卫不行，而邪热相搏则
患成。数日后渐宜温和气血，使阳动而阴随，气运而血行，则出脓而收敛。若专于清凉，气血凝
结则血死，血死则肌死而毙矣。
《黄帝内经》说：食用肥甘厚味过度，足以导致严重的疔疮，邪气侵入就像拿着空容器接东西一样容易。肥甘厚味的食物，使热毒在体内积聚，其病变多表现为严重的疽证。邪毒所侵犯的部位，是因为正气虚弱之处受邪，形成大疔、大疽，因为这些病灶根基深固于体内。又说：营气运行不畅，逆乱于肌肉纹理之间，就会发生痈肿。
对于疮疡病症，在初起之时，应当考察经络的传变规律、病位的表里深浅、患者体质的虚实状况以及邪气入侵的浅深程度，从而决定采用攻法还是补法。例如：如果肿胀伴有发热口渴、大便闭结不通，说明邪气在里，应采用疏通的方法；如果红肿疼痛，伴有恶寒发热、头痛，说明邪气在表，应采用发散的方法；如果肿痛剧烈，说明邪气在经络，应采用和解的方法；如果轻微肿胀疼痛且不化脓，说明气血虚弱，应采用补益托毒的方法；如果漫无边界地肿胀且不痛，或者不化脓，或者脓成但不溃破，说明气血极度虚弱，应采用峻猛补益的方法；如果肤色暗紫且轻微肿痛，或者脓成但排不出，或者腐肉不脱落，说明阳气虚寒，应采用温补的方法。如果拘泥于疮疡未溃破的阶段，一概使用败毒的药物，反而会损伤脾胃，不仅使不能化脓者无法化脓，而且已溃破者也难以收敛愈合。七恶（危重征象）蜂拥而至，大多导致死亡，这大概是一般原则。
痈疽这类病症有二十多种，最关键的是区分阴阳。发于阳经的，归属于六腑，属于表证、火证、实证；发于阴经的，归属于五脏，属于里证、郁证、虚证。所以阳证发作时，疮形大而高起，皮肤薄而颜色红赤，顶部有数十个如椒眼般的脓头，轻按即痛，形态大而浅表的称为痈。所以阴证发作时，疮形平塌内陷，皮肤厚实颜色淡白，肿胀坚硬不起，形状像老皮一样，重按感觉麻木隐痛，形态小而深在的称为疽。
又有“阳中之阴”的情况，看似有热实则非真热，虽然肿胀但本质是虚。如果颜色红但不躁动，虽然疼痛但没有脓液，或者浮起后又隐没，外表盛实内部腐烂；这类人多肥胖，肌肉紧实但内部虚弱。又有“阴中之阳”的情况，看似寒冷实则非真冷，不肿胀但实质充实，颜色微红且躁动，有脓且疼痛，形态虽然不盛大，但内部烦闷；这类人多消瘦，肌肉松弛但内部实热。
有由阳证转为阴证的，疾病起初发于阳经而极热，此时应当顺气调血。因为出现红肿发热、便秘烦躁口渴等热证，脉象洪数而实，即使在严冬，也应当暂时使用苦寒药物以泻除热毒。如果过度使用寒凉药，或误用性冷的草药，会导致气滞血凝而危及生命，此时必须紧急使用温热药物，使气行血和，才能化脓。
有由阴证转为阳证的，疾病起初发于阴经而极冷，此时应当内部使用平和补益之法，兼以宣通气血、助阳健脾进食。如果不肿胀不红赤，皮肤寒冷四肢冰冷，腹泻肠鸣，饮食不进，不时呕吐等寒证，脉象微弱而迟，即使在盛夏，也应当暂时使用辛温药物以助长阳气。倘若又误用凉药，必须紧急使用大热之剂来回阳救逆，如果不能回阳则死亡。
大概来说，阳代表气，阴代表血。阴不足则阳有余。血液涩滞、气机阻滞，营卫之气不能正常运行，邪热相互搏结则患病形成。几天后逐渐适宜温和气血，使阳气发动而阴血跟随，气机运转而血液运行，从而出脓并收敛愈合。如果专门使用清凉药物，会导致气血凝结，血液死结，血液死结则肌肉坏死而导致死亡。
The *Huangdi Neijing* (Yellow Emperor's Inner Canon) states: "Excessive consumption of rich and sweet foods is sufficient to generate severe ding sores (deep-seated infections), and the reception of pathogens is as easy as holding an empty vessel." Rich and greasy foods cause heat-toxins to accumulate internally, and their pathological changes often manifest as severe ju ulcers (deep-seated abscesses). The part of the body receiving the toxin does so because of deficiency in that area, leading to large ding or ju. This is because their roots are deep within the interior. It also states: "When Ying Qi (Nutritive Qi) fails to flow smoothly and rebels against the muscle texture, carbuncles and swellings arise."
Regarding ulcerative diseases, at the initial stage, one must examine the transmission of meridians, the exterior-interior location of the disease, the deficiency-excess status of the patient, and the depth of pathogen invasion, thereby deciding whether to use attacking or tonifying methods. For example: If swelling is accompanied by fever, thirst, and constipation, the pathogen is in the Interior; use dredging methods. If redness, swelling, pain, aversion to cold, fever, and headache occur, the pathogen is in the Exterior; use dispersing methods. If swelling and pain are severe, the pathogen is in the Meridians; use harmonizing methods. If there is slight swelling and pain without suppuration, it indicates Qi and Blood deficiency; use tonification with expulsion of pus. If there is diffuse swelling without pain, or failure to suppurate, or suppuration without rupture, it indicates severe Qi and Blood deficiency; use vigorous tonification. If the color is dark with slight swelling and pain, or pus forms but cannot discharge, or necrotic tissue does not slough off, it indicates Yang deficiency and Cold; use warming and tonifying methods. If one adheres strictly to the unruptured stage and indiscriminately uses detoxifying drugs, it will further damage the Spleen and Stomach. Not only will non-suppurating lesions fail to form pus, but ruptured ones will also struggle to heal. The Seven Evils (ominous signs) will arise simultaneously, often leading to death. This is a general principle.
There are more than twenty types of yong and ju ulcers, the most crucial being the differentiation between Yin and Yang. Those arising from Yang channels belong to the Six Fu Organs, representing Exterior, Fire, and Excess patterns. Those arising from Yin channels belong to the Zang Organs, representing Interior, Stagnation, and Deficiency patterns. Therefore, Yang eruptions are large and elevated, with thin skin and red color, featuring dozens of pore-like openings on the surface, painful upon light palpation, and characterized by large, shallow forms known as Yong (carbuncle). Conversely, Yin eruptions are flat and sunken, with thick skin and pale color, hard and non-elevated swelling resembling calloused skin, dull and hidden pain upon heavy palpation, and characterized by small, deep forms known as Ju (deep abscess).
There is also "Yin within Yang," which appears hot but is not truly hot; although swollen, the root is deficient. If red but not restless, painful but without pus, or floating then sinking, with external fullness but internal rot; such individuals are often obese with tight flesh but internal deficiency. There is also "Yang within Yin," which appears cold but is not truly cold; not swollen but substantively full, slightly red and restless, with pus and pain. Although the form is not grand, there is internal restlessness; such individuals are often emaciated with loose flesh but internal excess.
Cases where Yang transforms into Yin: The disease begins in Yang with extreme heat. One should regulate Qi and harmonize Blood. Because symptoms include redness, swelling, fever, constipation, restlessness, and thirst, with a surging, rapid, and excess pulse, even in severe winter, bitter-cold herbs should be temporarily used to purge heat-toxin. However, overuse of cold-cooling agents or mistaken use of cold-natured herbal medicines can cause Qi stagnation and Blood coagulation, leading to danger. In such cases, warm-hot medicines must be urgently used to promote Qi movement and Blood harmony, allowing pus to form.
Cases where Yin transforms into Yang: The disease begins in Yin with extreme cold. Internally, mild tonification should be used, combined with promoting Qi and nourishing Blood to assist Yang, strengthen the Spleen, and promote appetite. If there is no swelling or redness, cold skin and limbs, diarrhea with borborygmus, inability to eat, and frequent vomiting—cold symptoms with a weak, slow, and delayed pulse—even in midsummer, acrid-warm herbs should be temporarily used to assist Yang Qi. If cooling medicines are mistakenly administered again, urgent use of great-hot formulas is required to restore Yang; if Yang cannot be restored, death ensues.
Generally speaking, Yang represents Qi, and Yin represents Blood. When Yin is insufficient, Yang becomes excessive. Blood becomes stagnant, Qi becomes obstructed, Ying and Wei Qi fail to circulate, and evil heat contends, resulting in disease. After several days, it becomes appropriate to gently warm and harmonize Qi and Blood, causing Yang to move and Yin to follow, Qi to circulate and Blood to flow, leading to pus discharge and healing. If one exclusively uses cooling agents, Qi and Blood will coagulate, Blood will die, and dead Blood leads to necrosis of muscle and death.