生气通天论云膏粱之变足生大疔又云营气不从逆于肉理乃生痈肿
阴阳应象论云地之湿气感则害人皮肉筋脉
脉要精微论云诸痈肿筋挛骨病痛者此寒气之肿八风之变也
至真大要论云诸痛痒疮疡皆属心火
原病式云诸痛痒疮疡皆属心火者盖人近火气者微热则痒热甚则痛附近则灼而为疮皆火之
用也
或痒痛如针轻刺者犹飞迸火星灼之然也痒者美疾也故火旺于夏而万物蕃鲜荣美也炙之以火渍
之以汤而痒转甚者微热之所使也因而痒去者热令皮肤纵缓腠理开通阳气得泄热散而去故也或
夏热皮肤痒而以冷水沃之不去者寒能收敛腠理闭密阳气郁结不能散越怫热内作故也痒得爬而
解者爬为火化微则亦能令痒甚则痒去者爬令皮肤辛辣而属金化辛能散故金化见则火力分而解
矣或云痛为实痒为虚者非谓虚为寒也正谓热之微甚也或疑疮疡皆属火热而反腐出脓水者何也
犹谷肉果菜热极则腐烂而溃为污水也溃而腐烂者水之化也所谓五行之理过极则胜己者反来制
之故火热过极则反兼水化又如盐能固物令不腐烂者咸寒水化制其火热使不过极故得久固也万
物皆然
痈浅而大也经曰热胜血则为痈也三因方曰痈者壅也疽深而恶也三因方曰疽者沮也疖者节
也
疡有头小疮也
疹浮小瘾疹也
瘤气赤瘤丹 热胜气也火之色也
结核火气热甚则郁结坚硬如果中核也不必溃发但令热气散则自消也
《生气通天论》中说：饮食肥甘厚味过度，足以导致生大疔疮；又说：营气运行不畅，逆乱于肌肉纹理之间，就会发生痈肿。
《阴阳应象大论》中说：地之湿气，人体感受后就会伤害皮、肉、筋、脉。
《脉要精微论》中说：各种痈肿、筋脉拘挛、骨节疼痛，这些病症都是寒气引起的肿胀以及八风（八方之风）变化所致。
刘完素在《原病式》中说：“各种疼痛、瘙痒、疮疡，都归属于心火。”这是因为人靠近火源时，轻微的热感会引起瘙痒，热势严重则引起疼痛，接近火源则会灼伤皮肤形成疮疡，这都是火的作用表现。
有的瘙痒和疼痛像针轻轻刺扎一样，就像飞迸的火星灼烧皮肤那样。瘙痒是一种“美疾”（指阳气宣通的表现），所以火气旺盛于夏季，万物繁茂鲜艳、美好。用火灸烤或用热水浸泡而瘙痒反而加剧的，这是轻微热邪使然；如果因此瘙痒消除，是因为热令皮肤纵缓，腠理（皮肤纹理及汗孔）开通，阳气得以宣泄，热散而去，所以症状解除。
有的因夏季炎热皮肤瘙痒，用冷水浇洗却不去除的，是因为寒性能收敛，使腠理闭密，阳气郁结不能发散，怫热（郁积之热）在内产生，所以无效。
瘙痒通过抓挠而缓解的，因为抓挠属于“火化”，轻微抓挠也能让瘙痒更甚；严重抓挠后瘙痒消除，是因为抓挠使皮肤产生辛辣感而属于“金化”，辛能发散，所以当金化显现时，火力分散而解。
有人说痛是实证，痒是虚证，这并不是说虚就是寒，而是指热的程度轻重不同。
有人疑惑：既然疮疡都属于火热，为什么有些反而流出脓水呢？这就像谷物、肉类、水果、蔬菜热极则腐烂，溃烂成为污水一样。溃烂腐烂是水的气化表现，所谓五行的道理，事物发展到极端，克制自己的五行反而会来制约它。所以火热过极，反而兼有水的气化表现。又如盐能固定物体使其不腐烂，是因为咸寒的水气化作用制约了火热，使其不过极，所以能长久保持坚固。万物都是如此。
痈，特点是浅表且范围大。《内经》说：热胜血则为痈。《三因方》说：痈者，壅也（气血壅滞）。疽，特点是深在且性质恶劣。《三因方》说：疽者，沮也（阻滞不通）。疖，特点是局限如小节。
疡，有头的小疮。
The *Shengqi Tongtian Lun* (Treatise on the Connection between Vital Qi and Heaven) states: Excessive consumption of rich and sweet foods is sufficient to cause large ding sores; it also states that when Ying Qi (Nutritive Qi) fails to flow smoothly and rebels within the muscle tissue, carbuncles and swellings arise.
The *Yinyang Yingxiang Dalun* (Great Treatise on Yin-Yang Correspondences to Phenomena) states: Dampness from the earth, when contracted by the human body, damages the skin, flesh, sinews, and vessels.
The *Miyao Jingweilun* (Essential Microcosmic Treatise on Pulse Diagnosis) states: Various swellings, spasms of sinews, and bone pain are caused by the swelling of Cold Qi and changes due to the Eight Winds.
The *Zhihen Dayalun* (Great Treatise on the True Essentials) states: All pain, itching, sores, and ulcers belong to Heart Fire.
Liu Wansu in the *Yuanbingshi* (Manual of Original Causes of Diseases) explains: "All pain, itching, sores, and ulcers belong to Heart Fire." This is because when a person approaches fire, slight heat causes itching, severe heat causes pain, and close proximity burns the skin to form sores; these are all manifestations of the function of Fire.
Some experience itching and pain as if lightly pricked by needles, similar to flying sparks burning the skin. Itching is considered a "beautiful disease" (indicating smooth Yang Qi circulation); thus, Fire dominates in summer when all things flourish and appear vibrant. If moxibustion or hot water immersion exacerbates itching, it is due to mild heat. If itching subsides afterward, it is because heat relaxes the skin, opens the Couli (pores and interstices), allows Yang Qi to vent, and dissipates the heat.
If cold water washing fails to relieve summer-induced skin itching, it is because Cold constricts and closes the Couli, causing Yang Qi to stagnate and internal heat to accumulate.
Itching relieved by scratching occurs because scratching induces a "Fire transformation"; mild scratching may worsen itching, but vigorous scratching relieves it by inducing a "Metal transformation" (spicy sensation), which disperses. When Metal transformation appears, the Fire force divides and resolves.
Some claim pain indicates excess and itching indicates deficiency, not meaning deficiency is Cold, but rather referring to the degree of heat.
One might question: If sores and ulcers all belong to Fire/Heat, why do some discharge pus? This is like grains, meats, fruits, and vegetables rotting and turning into liquid when heat reaches its extreme. Rotting is a manifestation of Water transformation. According to Five Element theory, when things reach an extreme, the element that controls them counteracts them. Thus, when Fire/Heat is extreme, it assumes Water characteristics. For example, salt preserves food because its salty-cold Water nature restrains Fire/Heat, preventing excess, thus maintaining stability. This applies to all things.
A Yong (Carbuncle) is superficial and broad. The Classics state: Heat overcoming Blood results in Yong. The *Sanyin Fang* states: Yong means obstruction (Qi and Blood stagnation). A Ju (Deep-seated abscess) is deep and malignant. The *Sanyin Fang* states: Ju means blockage. A Ji (Furuncle) is limited like a joint/nodule.
Yang refers to small sores with heads.
Zhen refers to floating, small urticaria/rashes.
Liu (Tumor/Nodule) includes Qi Chi Liu (Red Nodule/Erysipelas), caused by Heat overcoming Qi; red is the color of Fire.
Jiehe (Scrofula/Knots) occurs when Fire/Heat is excessive and stagnates, becoming hard like a fruit pit. It does not necessarily require ulceration; if Heat dissipates, it resolves spontaneously.