夫大肠之下血也，一曰肠风，一曰脏毒。肠风者，邪气外入，随感随见，所以色清而鲜
；脏毒者，蕴积毒久而始见，所以色浊而黯。经云∶阴络伤，则血内溢而便血。人惟醉饱房
劳，坐卧风湿，生冷停寒，酒面积热，使阴络受伤，脾胃虚损，外邪得而乘之，以致营血失
道，渗入大肠而下，久则元气愈陷，湿热愈深，而变为脏毒矣。先便而后血者其来远，先血
而后便者其来近。治法大要，先当解散脾胃风邪，热则败毒散，冷则不换金正气散加川芎、
当归，后随其冷热治之。其或内伤阳气不足，下焦之阴，无元阳以维之而下血者，宜补中益
气汤、六君子及参苓白术散加芎、归、枳壳、地榆、槐花等。盖血气出于谷气，故必赖补中
升阳，以胃药收功，胃气一回，血自循经络矣。
附∶林氏谓∶肠风者，本足阳明清气不能升发透达于四肢腠理之间，下陷于大肠，大肠
之血脉亦随此气而虚陷，陷久则气血郁结而化为湿热，因此血随气滞，凡登圊气陷火迫之时
，其血先粪而至，至则清散不多。初起谓之肠风，盖因方中多用荆芥、防风、升麻诸风药，
升举清阳之气，遂疑为外感之风也；即使是风，亦血热所化之风，岂外风能入于大肠也哉。
至于脏毒者，因肠风日久，气血两虚，虚陷之气日甚，而大肠之湿热蕴积日深，手阳明大肠
为积血之处，其势必随气下陷，从粪之前后而来，来虽不痛，而其色多黑黯成块，故有毒之
名，而实无痔漏、肠痈脓血疼痛之毒也。若其病久远，气血愈亏，则脾胃之元气谅必先亏，
不能统运周身血脉，使之流行无碍，亦随陷于大肠，而成结阴便血之证。在下清气不举。便
血而兼飧泄之病；在上浊气凝结，中满而兼喘嗽之恙；甚至肢体浮肿，胸腹胀闷而死。
是证应分为三∶轻曰肠风，甚则脏毒，重则结阴也。（结阴者，阴气内结，不得外行，渗入肠
间，乃寒湿生灾而阴邪之胜也。）
附∶冯鲁瞻曰∶风寒暑湿热外邪所乘，皆可下血。盖风喜伤肝，肝伤则不能藏血，因致
下血；醉后饮冷，寒饮内伤，血为寒凝，渗入大肠，因致下血；内外伤湿，湿伤凝胃，随气
下流，故致下血；膏粱人浓味酒色，藜藿人劳役过度，以致热积下焦，故致下血；更有内伤
阳气不足，阴无所 ，脾虚阳气下陷，不能统血，每致下血。初起之脉，或沉数有力，或弦
数不清，久则芤数无力，或沉涩而弱，至结阴脾虚之脉，非芤涩，则虚搏。治法∶初则宜于
升阳清热，次则清补相兼、和血解毒。结阴则当升清利浊，兼于温补其血可也。
关于大肠下血的症状，分为两种：一种叫肠风，一种叫脏毒。所谓肠风，是指外邪侵入人体，感邪后立即发病，因此血色清亮而鲜红；所谓脏毒，是指体内蕴积毒素日久后才显现出来，因此血色浑浊而暗紫。医经记载：“阴络受损，则血液内溢而导致便血。”人们往往因为醉酒饱食、房事过度，久坐卧于风湿之地，食用生冷导致寒气停滞，或饮酒过多导致积热，使得阴络受伤，脾胃虚弱受损，外邪趁机侵袭，致使营血运行失常，渗入大肠而下泄。时间久了，元气更加下陷，湿热更加深重，从而演变为脏毒。先排便后出血的，病位较远；先出血后排便的，病位较近。治疗的大要，首先应当疏散脾胃的风邪，属热证的用败毒散，属寒证的用不换金正气散加川芎、当归，之后根据寒热情况辨证施治。如果是由于内伤导致阳气不足，下焦之阴失去元阳的维系而下血，适宜使用补中益气汤、六君子汤及参苓白术散，并加入川芎、当归、枳壳、地榆、槐花等药物。因为气血源于水谷之气，所以必须依靠补益中气、升举阳气的方法，以调理胃气的药物收功，胃气恢复，血液自然能循行于经络之中。
附注：林氏认为：肠风的本质是足阳明胃经的清气不能升发透达至四肢腠理之间，反而下陷于大肠，大肠的血脉也随着这股气机而虚陷，久陷则气血郁结化为湿热，因此血液随气机阻滞，凡是在如厕时气机下陷、火邪逼迫的时候，血液先于粪便而出，流出后清澈且量不多。初起称为肠风，大概是因为方剂中多用荆芥、防风、升麻等祛风药，以升举清阳之气，于是误以为是外感之风；即使是风，也是由血热所化生的风，难道是外风能进入大肠吗？至于脏毒，是因为肠风日久，导致气血两虚，虚陷的气机日益严重，而大肠的湿热蕴积日益加深，手阳明大肠经是积血之处，其势必然随气机下陷，从粪便的前后排出，虽然来势不痛，但血色多黑黯成块，所以有毒的名称，但实际上并没有痔漏、肠痈脓血疼痛那样的毒症。如果病情迁延久远，气血更加亏损，那么脾胃的元气想必先已亏虚，不能统摄和运化周身血脉，使其流通无阻，也会随之陷于大肠，形成结阴便血的证候。在下部表现为清气不举，便血兼有完谷不化的飧泄病；在上部表现为浊气凝结，胸脘痞满兼有喘咳的病；甚至发展到肢体浮肿，胸腹胀闷而死。这种病症应分为三类：轻的称为肠风，重的称为脏毒，极重的称为结阴。（所谓结阴，是指阴气在内结聚，不能向外运行，渗入肠间，这是寒湿为灾而阴邪胜盛的缘故。）
附注：冯鲁瞻说：风寒暑湿热等外邪侵袭，都可以导致下血。大概风邪容易损伤肝脏，肝受损则不能藏血，因而导致下血；醉酒后饮用冷水，寒饮内伤，血液被寒邪凝滞，渗入大肠，因而导致下血；内外受湿，湿气损伤凝聚胃气，随气机下流，因而导致下血；富贵之人饮食肥甘厚味、酗酒好色，贫贱之人劳役过度，导致热积于下焦，因而导致下血；更有内伤导致阳气不足，阴无所依附，脾虚阳气下陷，不能统摄血液，常常导致下血。初起时的脉象，有的沉数有力，有的弦数不清；久了则出现芤数无力，或沉涩而弱，到了结阴脾虚的脉象，不是芤涩，就是虚搏。治疗方法：初起宜于升阳清热，其次清补兼施、调和血液解毒。若是结阴证，则应当升清利浊，兼以温补血液为宜。
Regarding hematochezia (blood in stool) from the Large Intestine, there are two types: one is called Changfeng (Intestinal Wind), and the other is called Zangdu (Visceral Toxin). Changfeng refers to external pathogenic factors invading the body, manifesting immediately upon infection; therefore, the blood color is clear and bright red. Zangdu refers to toxins accumulating internally for a long time before manifesting; therefore, the blood color is turbid and dark purple. The Classics state: "When Yin collaterals are damaged, blood overflows internally, resulting in hematochezia." People often suffer from this due to drunkenness and overeating, excessive sexual activity, sitting or lying in damp-wind environments, retention of cold from raw and cold foods, or accumulation of heat from excessive alcohol consumption. These factors injure the Yin collaterals and damage the Spleen and Stomach, allowing external pathogens to take advantage. This causes Ying Blood (Nutritive Blood) to lose its proper course, seeping into the Large Intestine and flowing downward. Over time, Yuan Qi (Original Qi) sinks further, and damp-heat deepens, transforming into Zangdu. If defecation precedes bleeding, the source is distant; if bleeding precedes defecation, the source is proximate. The general principle of treatment is first to dissipate wind pathogens in the Spleen and Stomach. For heat patterns, use Baidu San (Toxin-Dissipating Powder); for cold patterns, use Bu Huan Jin Zhengqi San (Golden Replacement Upright Qi Decoction) added with Chuanxiong Rhizome (Chuanxiong) and Angelicae Sinensis Radix (Danggui). Subsequently, treat according to cold or heat. If internal injury leads to insufficient Yang Qi, and Yin in the Lower Jiao lacks the support of Yuan Yang, causing bleeding, it is appropriate to use Buzhong Yiqi Tang (Tonify the Middle and Augment the Qi Decoction), Liujunzi Tang (Six Gentlemen Decoction), or Shenling Baizhu San (Ginseng, Poria, and Atractylodes Macrocephala Powder), added with Chuanxiong, Danggui, Aurantii Fructus (Zhike), Sanguisorbae Radix (Diyu), and Sophorae Flavescentis Flos (Huaihua). Since Qi and Blood originate from Gu Qi (Grain Qi), they must rely on tonifying the Middle and raising Yang, concluding with stomach-regulating herbs. Once Stomach Qi returns, blood will naturally circulate within the meridians.
Supplement: Lin Shi stated that the essence of Changfeng is that the Clear Qi of Foot-Yangming Stomach Meridian cannot ascend and penetrate to the limbs and interstices, but instead sinks into the Large Intestine. The blood vessels of the Large Intestine also become deficient and sink with this Qi. After prolonged sinking, Qi and Blood stagnate and transform into damp-heat. Consequently, blood follows the stagnant Qi. During defecation, when Qi sinks and Fire forces it, blood appears before the feces, flowing out clearly and in small amounts. Initially called Changfeng, this name likely arises because formulas often use wind-dispelling herbs like Schizonepetae Spica (Jingjie), Saposhnikoviae Radix (Fangfeng), and Cimicifugae Rhizoma (Shengma) to raise Clear Yang, leading to the misconception of external Wind. Even if it is Wind, it is Wind transformed from Blood Heat; how could external Wind enter the Large Intestine? As for Zangdu, it occurs because Changfeng persists for a long time, leading to deficiency of both Qi and Blood. The sinking Qi becomes increasingly severe, and damp-heat in the Large Intestine accumulates deeply. Hand-Yangming Large Intestine Meridian is the site of accumulated blood; its momentum inevitably sinks with the Qi, emerging before or after the feces. Although painless, the blood is often dark black and clotted, hence the name "Toxin," though it lacks the toxicity of hemorrhoids, fistulas, intestinal abscesses, pus, blood, or pain. If the disease lingers, Qi and Blood become more deficient, and Spleen-Stomach Yuan Qi is undoubtedly depleted first. It can no longer control and transport the blood vessels of the whole body, preventing smooth flow, and thus sinks into the Large Intestine, forming the syndrome of Jieyin Hematochezia. In the lower part, it manifests as failure to raise Clear Qi, with hematochezia accompanied by undigested food diarrhea (Xunxie); in the upper part, it manifests as congealed Turbid Qi, with chest fullness accompanied by wheezing and coughing; eventually leading to limb edema, chest and abdominal distension, and death. This condition should be divided into three categories: mild is Changfeng, severe is Zangdu, and critical is Jieyin. (Jieyin means Yin Qi knots internally and cannot move outward, seeping into the intestines; this is disaster caused by cold-dampness and the predominance of Yin pathogens.)
Supplement: Feng Luzhan said: External pathogens such as Wind, Cold, Summer-heat, Dampness, and Heat can all cause bleeding. Wind tends to injure the Liver; when the Liver is injured, it cannot store Blood, leading to bleeding. Drinking cold liquids after drunkenness injures the interior with Cold, coagulating Blood, which seeps into the Large Intestine, causing bleeding. Internal and external Dampness condenses and injures the Stomach Qi, flowing downward with Qi, causing bleeding. Those who consume rich foods, strong flavors, alcohol, and engage in excessive sex, or those who labor excessively, lead to heat accumulation in the Lower Jiao, causing bleeding. Furthermore, internal injury with insufficient Yang Qi leaves Yin without support; Spleen deficiency with sinking Yang Qi fails to control Blood, often causing bleeding. At the onset, the pulse may be deep and rapid with force, or wiry and uncountable. Later, it may be hollow and rapid without force, or deep, choppy, and weak. In cases of Jieyin and Spleen deficiency, the pulse is either hollow and choppy or deficient and thready. Treatment methods: Initially, it is suitable to raise Yang and clear heat; subsequently, clear and tonify simultaneously, harmonize Blood, and detoxify. For Jieyin, one should raise Clear Qi and drain Turbid Qi, combined with warming and tonifying the Blood.