时疫初起在表时，头痛、发热、小便不利者，热入膀胱也，益元散主之，四苓散、猪苓汤皆可用。东垣云∶小
便不利而渴者，热在上焦，法当淡渗；小便不利而不渴者，热在下焦，法当苦寒。此可为据。
时疫传里，大便闭而小便不利者，当先通大便，大便通小便自利，此惟时疫为然，他病则否。时疫屡经汗、下，
小便不利者，阴竭也，为难治，知母、黄柏、生地、麦冬之类治之，或生脉、六味皆可，然多至少腹如鼓而不救也。
凡小便不利，日久下关不通，必反于上。往往有呕吐、呃逆、涓滴不能下咽，至汤药不进者。当用敷脐法∶
大田螺一枚，捣烂，入麝香三厘，敷脐上，帛束之即通，一见点滴即受汤药。古法有用葱熨及井底泥敷少腹者，
俱可参用，但不宜于阴竭之虚人耳。
时疫未传变时，小便多如常。热一传入里则黄，热甚则赤，热入血分蓄血则黑。小便可验里热之有无、深浅、
多寡，但不可以作专证。疫邪在表小便黄，即于解表中加清凉药。邪入里小便黄赤，虽手足逆冷，亦当攻里逐热。
疫邪已退，表里俱和，小便黄赤未退，仍当清利余邪。惟小便黑者，当逐瘀清热为主，犀角地黄汤加大黄等类。有
屡经汗、下，清凉太过，表里俱无热邪，而滑泻腹痛，小便黄赤者，当理脾升阳为主，亦治药非治病也。
时疫（流行性瘟疫）初起，病邪在体表时，若出现头痛、发热、小便不通畅的症状，这是热邪侵入膀胱所致，主用益元散治疗，四苓散、猪苓汤也都可以使用。李东垣曾说：小便不通畅且伴有口渴的，是热邪在上焦，治法应当采用淡味渗湿利水的方法；小便不通畅且不伴有口渴的，是热邪在下焦，治法应当采用苦寒清热的方法。这一观点可以作为依据。
当时疫传入体内脏腑，出现大便闭塞且小便不通畅的情况时，应当先通导大便，大便通畅后小便自然就会通利，这种情况只有时疫才会这样，其他疾病则不是如此。当时疫经过多次发汗、攻下治疗后，仍然小便不通畅的，属于阴液枯竭，属于难治之症，可用知母、黄柏、生地黄、麦冬等药物治疗，或者使用生脉散、六味地黄丸也可以，但这类患者大多会出现小腹胀大如鼓且无法救治的情况。
凡是小便不通畅，日久导致下窍（尿道）闭塞不通的，病气必然反逆向上。往往会出现呕吐、呃逆，点滴水浆都无法咽下，甚至连汤药都进不去的情况。此时应当采用敷脐法：取大田螺一枚，捣烂，加入麝香三厘，敷贴于肚脐上，用丝帛束紧固定，即可通利小便，一旦见到有尿液滴出，就可以服用汤药了。古法中有用葱白熨烫及用井底泥敷贴小腹的，都可以参考使用，但不适用于阴液枯竭的虚损体质患者。
当时疫尚未发生传变时，小便通常像正常人一样。热邪一旦传入体内，小便颜色就会变黄；热势严重则变为红色；热邪深入血分形成蓄血证，则小便颜色发黑。可以通过观察小便来验证体内是否有热邪、热邪的深浅程度以及多少，但不能将其作为唯一的诊断依据。疫邪在体表时小便发黄，就应当在解表方剂中加入清凉药物。邪气传入体内，小便黄赤，即使手足逆冷，也应当攻逐里热。疫邪已经消退，表里调和，但小便黄赤仍未退去，仍应当清利残留的邪气。只有当小便发黑时，才应当以逐瘀清热为主要治法，使用犀角地黄汤加大黄等类药物。如果有经过多次发汗、攻下，清凉药物使用过度，导致表里都没有热邪，反而出现滑泄腹泻、腹痛，小便黄赤的情况，应当以调理脾胃、升举阳气为主要治法，这也是因为治疗用药不当而非疾病本身导致的。
When epidemic pestilence (Shi Yi) initially occurs and the pathogen is in the exterior, if symptoms such as headache, fever, and dysuria (difficult or painful urination) appear, this indicates heat entering the Bladder. The primary treatment is Yiyuan San (Benefit the Origin Powder); Siling San (Four-Ingredient Powder for Leaching Out Dampness) and Zhuling Tang (Polyporus Decoction) are also applicable. Li Dongyuan stated: When dysuria is accompanied by thirst, the heat is in the Upper Jiao (Upper Burner), and the method should be light and permeating to leach out dampness; when dysuria occurs without thirst, the heat is in the Lower Jiao (Lower Burner), and the method should be bitter and cold to clear heat. This serves as a reliable basis.
When epidemic pestilence transmits inward, resulting in constipation and dysuria, one must first unblock the stool; once the stool is unblocked, urination will naturally become free. This phenomenon is specific to epidemic pestilence and does not apply to other diseases. If dysuria persists after repeated sweating and purging treatments for epidemic pestilence, it indicates exhaustion of Yin fluids, which is difficult to treat. It can be managed with herbs such as Anemarrhenae Rhizoma (Zhimu), Phellodendri Cortex (Huangbai), Rehmanniae Radix Recens (Shengdi), and Ophiopogonis Radix (Maidong), or formulas such as Shengmai San (Generate the Pulse Powder) and Liuwei Dihuang Wan (Six-Ingredient Pill with Rehmannia). However, patients often present with a distended abdomen like a drum and may prove incurable.
In cases of chronic dysuria where the lower orifices remain blocked for a long time, the pathological qi inevitably rebels upward. This often manifests as vomiting, hiccups, inability to swallow even small amounts of liquid, and eventually the inability to take any decoction. In such situations, an umbilical application method should be used: Take one large river snail, mash it thoroughly, add 3 li (approx. 0.15g) of Moschus (Shexiang), and apply it to the umbilicus, securing it with silk bandages. Urination will likely resume immediately; once drops of urine appear, oral decoctions can be administered. Ancient methods also include warming the area with scallions or applying mud from the bottom of a well to the lower abdomen, which can be referenced, but these are not suitable for patients with Yin exhaustion and deficiency.
Before the transmission of epidemic pestilence, urination is usually normal. Once heat transmits inward, the urine becomes yellow; with severe heat, it turns red; if heat enters the Blood level causing blood stasis accumulation, the urine turns black. Urine observation can verify the presence, depth, and quantity of interior heat, but it should not be used as a sole diagnostic criterion. If the epidemic pathogen is in the exterior and urine is yellow, cooling herbs should be added to exterior-resolving formulas. If the pathogen has entered the interior and urine is yellow-red, even if there is cold extremities (cold hands and feet), interior purging to remove heat is still required. After the epidemic pathogen has receded and the exterior and interior are harmonized, if yellow-red urine persists, residual pathogens should still be cleared and diuresis promoted. Only when urine is black should the primary treatment focus on dispelling stasis and clearing heat, using formulas such as Xijiao Dihuang Tang (Rhinoceros Horn and Rehmannia Decoction) with added Rhubarb. If repeated sweating and purging, along with excessive use of cooling herbs, have eliminated all heat from the exterior and interior, yet diarrhea with abdominal pain and yellow-red urine persist, the treatment should focus on regulating the Spleen and raising Yang Qi. This situation arises from improper medication rather than the disease itself.