痢，泻也。大便通利，常也。痢者，乃里急欲利，复后重而不利。后重，即后坠，痢之发也，身作寒热，
呕吐，烦闷，水浆不入，腹痛，下痢或赤或白，或赤白相兼，里急后重，昼夜数十余次。此痢之重者也，治得
其法，虽重可愈。初起时，若有风寒表证，于治痢药中，当加发散；若不发散，径治其痢，必乱其经脉，逆其
气机，病转剧矣。外邪既去，但治其痢，更分寒、热、虚、实，顾本顾标，如但以通利之法治之，先通后补，
不若标本兼治，补泻并行之为得也。若下痢纯红，身热不退，水谷不入，是为死证。经云∶肠 下血，身热则
死。谓余血下泄，阳热外浮，阴阳离脱也。若痢后下血水，其身发热，亦为死证。痢后则肠垢已竭，下血水乃
从阳入阴，胞中并伤，世有下屋漏水之说，则血水其渐也。若色如鱼脑，此热毒入肠，当清热和血也。色如酱
褐，乃下焦虚寒，亦非善证，当温经散寒。如白沫冻汁，则为寒积。世医有赤属火、白属寒之说，于理亦似，
但赤色而中土虚胃气弱者，当用温药以从治，不宜凉药以对治
也。凡痢初起，作呕无害，若日久脾虚，三焦寒而呕者，亦将危矣。又凡下痢必痛，痛者可治，谓有积也；
不痛者，是为肾泄，难治，一起便宜温补，不宜行泄，若行泻于前，温补于后，亦难生矣。凡痢属三阳，精神不
惫而能食者，当分新久，或泻或补，或泻补兼施；若身体疲倦，不能饮食，而属三阴者，止宜温补，不宜通利；
亦有下痢无积，日夜十余次，解时微痛，是名脾泻，又名洞泄，亦宜温补，不宜通利。有脾家实，而腐秽当下
者，乃新病为然，必非久也。有夏秋虚寒下痢，治得其法，至冬稍痊，明春方愈者；有夏秋实热下痢，治不得
宜，乍轻乍重，至明春方死者。有痢疾初起，点滴艰涩，里急后重，宜芒硝、大黄通利者，所谓通则不痛也。
痢之轻者，名曰积，饮食失宜，寒积下焦也。一时腹痛，雷鸣暴注，名曰水泻，水谷不分，从小肠而下注也。
凡下痢，有粪者轻，无粪者重。盖粪从肠中出，积从肠外出；肠中出者出之易，肠外出者出必难，故后重而痛
也。
痢疾，属于泄泻的一种。大便通畅流利，是正常状态。所谓痢疾，是指腹部紧迫想要排便，但又有肛门坠胀感却排不出或排不净。所谓的“后重”，就是肛门下坠的感觉。痢疾发作时，身体出现寒热交替，伴有呕吐、心烦闷乱，连水浆都喝不下，腹痛，排出痢疾脓血，颜色或是红色，或是白色，或者红白相间，里急后重，一天夜间要腹泻数十次甚至更多。这是病情严重的痢疾，如果治疗方法得当，即使病情严重也能治愈。
在发病初期，如果有风寒表证（外感风寒引起的体表症状），在治疗痢疾的药物中，应当加入发散表邪的药物；如果不进行发散治疗，直接治疗痢疾，必然会扰乱经脉，逆乱气机，导致病情加重。
当外邪去除后，只治疗痢疾本身，更要分辨寒、热、虚、实四种性质，既要顾护根本（正气），又要兼顾标症（病邪）。如果只是单纯用通利的方法治疗，先通利后补益，不如标本兼治、补泻并行的方法更为恰当。
如果下痢纯为红色血液，身体发热不退，饮食无法进入，这属于死证。医经说：“肠道下血，若身体发热则预后不良致死。”这是因为余血下行外泄，阳热之气浮越于外，导致阴阳离决脱失。
如果在痢疾之后出现下血水，且身体发热，也属于死证。痢疾之后，肠中的垢浊之物已经排尽，此时下血水说明病邪从阳分深入阴分，胞宫（此处指下焦脏腑）同时受损，世间有“下屋漏水”的说法，指的就是这种血水逐渐流失的情况。
如果痢疾颜色像鱼脑一样，这是热毒侵入肠道，应当采用清热和血的治疗方法。如果颜色像酱褐色，这是下焦虚寒，也不是好征兆，应当采用温经散寒的方法。如果是白色的泡沫冻汁样排泄物，则是寒邪积滞所致。
世间的医生有“红色属火、白色属寒”的说法，从道理上看似乎也成立，但如果痢疾色红而脾胃虚弱、胃气弱者，应当使用温药来顺从其病势（从治），而不宜用凉药来对抗治疗（对治）。
凡是痢疾初起，出现呕吐并无大碍；但如果日久导致脾虚，三焦寒冷而呕吐的，也将危及生命。
另外，凡是下痢必然疼痛，疼痛的可以治疗，因为这说明体内有积滞；不疼痛的，称为肾泄，难以治疗，一开始就适宜温补，不宜使用行气泄下的方法。如果在前面使用泻法，后面再使用温补，也难以挽回生机。
凡是痢疾属于三阳经病变，精神不疲惫且能进食的，应当根据病程新久，分别采用泻法、补法，或者泻补兼施；如果身体疲倦，不能进食，且属于三阴经病变的，只适宜温补，不宜使用通利之法。
也有下痢没有积滞，日夜十余次，排便时轻微疼痛的，这叫脾泻，又叫洞泄，也适宜温补，不宜通利。
如果是脾家实证，腐秽之物应当排出的情况，这只是新病才会这样，必定不是久病。
有的患者在夏秋季节患虚寒下痢，治疗方法得当，到了冬天稍微痊愈，到明年春天才完全康复；有的患者在夏秋季节患实热下痢，治疗不得当，病情时轻时重，到了明年春天反而死亡。
有的痢疾初起，点滴难出，艰涩不通，里急后重，适宜使用芒硝、大黄通利的，这就是所谓的“通则不痛”。
病情较轻的痢疾，名叫“积”，是由于饮食不当，寒邪积滞在在下焦所致。一时腹痛，肠鸣如雷，暴注下迫，名叫“水泻”，是因为水谷不分，从小肠向下灌注所致。
凡是下痢，有粪便的病情轻，无粪便的病情重。因为粪便是从肠中出来的，积滞是从肠外出来的；从肠中出来的容易排出，从肠外出来的排出必然困难，所以会出现肛门坠胀和疼痛。
Dysentery is a type of diarrhea. Smooth and frequent bowel movements are normal. Dysentery refers to the sensation of tenesmus (urgency to defecate) combined with a feeling of heaviness or bearing down in the rectum, yet unable to pass stool effectively. "Tenesmus" implies a downward dragging sensation. When dysentery occurs, the body experiences alternating chills and fever, accompanied by vomiting, mental restlessness and oppression, inability to take in fluids or food, abdominal pain, and passage of dysenteric discharge which may be red, white, or mixed red and white. The patient suffers from tenesmus and may defecate dozens of times day and night. This represents severe dysentery; if treated correctly, even severe cases can be cured.
In the early stage, if there are exterior syndromes caused by wind-cold, dispersing agents should be added to the dysentery-treating formula. If dispersing is not performed and treatment focuses solely on dysentery, it will inevitably disrupt the meridians and reverse the flow of qi, causing the disease to worsen.
Once external pathogens are eliminated, treatment should focus only on dysentery, further distinguishing between cold, heat, deficiency, and excess patterns. One must attend to both the root (zhengqi/healthy qi) and the branch (pathogenic factors). Merely using draining methods, treating the branch first and the root later, is inferior to a strategy that treats both root and branch simultaneously, combining tonification and purgation.
If the discharge consists purely of blood, with persistent fever and inability to ingest food, this is a death sign. The Classics state: "Bleeding from the intestines with fever indicates death." This is because residual blood is leaking out while yang-heat floats externally, leading to the separation and collapse of yin and yang.
If bloody water is passed after dysentery, accompanied by fever, this is also a death sign. After dysentery, the intestinal turbidity has been exhausted; passing bloody water indicates the pathogen has moved from the yang level to the yin level, damaging the lower jiao (lower burner). The world describes this as "water leaking from the bottom house," referring to the gradual loss of blood and fluids.
If the color resembles fish brains, this indicates heat-toxin entering the intestines; one should clear heat and harmonize the blood. If the color resembles dark brown sauce, this indicates deficiency-cold in the lower jiao, which is also an unfavorable sign; one should warm the meridians and dispel cold. If the discharge consists of white froth or jelly-like substances, this indicates accumulation of cold.
Some physicians claim that red indicates fire and white indicates cold. While this seems plausible, if the discharge is red but the spleen-earth is deficient and stomach qi is weak, one should use warm medicines to treat according to the nature of the disease (conforming treatment), rather than using cooling medicines for opposing treatment.
Generally, vomiting at the onset of dysentery is harmless. However, if vomiting occurs due to long-standing spleen deficiency and cold in the three jiao, the condition will become critical.
Furthermore, dysentery is always painful; painful cases are treatable because they indicate the presence of stagnation. Painless cases are known as Kidney Diarrhea and are difficult to treat; immediate warm tonification is appropriate, avoiding moving and draining methods. If draining is used first followed by warm tonification, survival is unlikely.
For dysentery belonging to the Yang meridians, where spirit is not exhausted and appetite remains, treatment should distinguish between new and old conditions, employing purgation, tonification, or a combination of both. For dysentery belonging to the Yin meridians, characterized by physical fatigue and inability to eat, only warm tonification is suitable, avoiding draining methods.
There are also cases of dysentery without stagnation, occurring more than ten times a day with slight pain during defecation, known as Spleen Diarrhea or Hole Diarrhea; these also require warm tonification and avoid draining.
When there is excess in the spleen requiring the expulsion of rotten filth, this applies only to new diseases, not chronic ones.
Some patients suffer from deficiency-cold dysentery in summer and autumn; if treated correctly, they may improve slightly in winter and fully recover in the following spring. Others suffer from excess-heat dysentery in summer and autumn; if treated improperly, their condition fluctuates, and they may die in the following spring.
In early-stage dysentery with scanty, difficult passage, tenesmus, and heaviness, purgatives like Mangxiao (Natrii Sulfas) and Dahuang (Rhei Radix et Rhizoma) are suitable, following the principle that "free flow eliminates pain."
Mild dysentery is called "Accumulation," caused by improper diet and cold accumulation in the lower jiao. Sudden abdominal pain, borborygmus (rumbling in the intestines), and violent watery diarrhea are called "Water Diarrhea," resulting from the failure to separate clear and turbid fluids, flowing down from the small intestine.
Generally, dysentery with feces is mild, while dysentery without feces is severe. Feces originate from within the intestines, while accumulations originate from outside. What comes from within is easy to expel; what comes from outside is difficult to expel, hence the tenesmus and pain.