经曰。腰者肾之府。痘疮见腰痛。或痛连背脊。转侧不能。皆因肾郭空虚。邪火亢盛。真阴
不能胜邪之故。急宜四顺清凉饮。救热存阴为务。若痘未出而骤热腰痛。面色紫赤。痘必干枯紫
黑。此肾脏火毒盛剧。急用百祥丸。或水调元明粉以下夺其势。后用消毒饮加防风、紫草、连翘、
木通。若腰下见紫黑成片如蚤啮者。不出七朝必死。
痘疹要小便清而长。大便疏而润。谓之里气和。一有艰阻。则毒邪内蓄。肠胃壅遏不能传
化。便宜清解。得大便通。溺自利矣。三黄丸、四顺饮、前胡枳壳汤之类。此专为痘始发时而言。
若痘正养浆时而二便秘者。宜审虚实治之。中病即止。不可过剂。若饮食如常。二便如昔。内证
平和。不可温补。亦不可妄施攻击也。
痘疮出后。灌浆之时。虽要大府坚实为顺。若痘出五六日不大便。此毒火内乘。津液外耗。
肠胃干枯而秘也。四顺饮。若色白少神不食。呕吐清水者。虚秘也。钱氏异功散加归、芍。若血
热口干。烦躁便秘。四顺饮加紫草。使其便利二三度。热毒自解。烦躁自宁。若有风寒。先宜解
散。然后可下。若不先解。恐表邪乘虚入里。痘反伏而不发。发亦不齐。遂成塌陷焦枯。势所必
至。如六七日灌脓之时。壮热脉盛而大便不通。加味消毒饮。及蜜煎导以润下之。否则腹胀喘满
矣。有过利小便。津液内耗而秘者。生脉散加当归。又气血俱化成浆。而四五日不大便者。只宜
清凉活血。浆足自行。
不须治之。薛氏云。痘疹大便不通。当分辨虚实。以手足冷热。及饮水饮汤验之。
《黄帝内经》说：腰是肾的府邸。痘疮患者出现腰痛，或者疼痛牵连背部脊柱，转身侧卧困难，这都是因为肾气亏虚，邪火亢盛，真阴无法制约邪气的缘故。此时应当紧急使用四顺清凉饮，以救治热邪、保存阴液为要务。如果痘疹尚未发出而突然高热并伴有腰痛，面色紫红发赤，痘疹必然干枯呈紫黑色，这是肾脏火毒极其旺盛的表现，应紧急使用百祥丸，或者用水调服元明粉来攻下以遏制病势。之后再用消毒饮，加入防风、紫草、连翘、木通。如果在腰部以下出现成片紫黑如被跳蚤叮咬般的斑纹，不出七天必定死亡。
痘疹病症要求小便清澈且尿量长，大便通畅且滋润，这叫做“里气和”。一旦有排便排尿艰难阻滞的情况，就会导致毒邪在体内蓄积，肠胃壅塞阻碍无法正常传导化生。此时适宜采用清热解表的方法，使大便通畅，小便自然也就利落了。三黄丸、四顺饮、前胡枳壳汤等方剂，这些是专门针对痘疹初发阶段而言的。如果痘疹正处于养浆（化脓）阶段而出现二便闭塞的，应当审察虚实进行辨证治疗。中病即止，不可用药过量。如果饮食正常，二便如常，内部证候平和，就不可使用温补法，也不可胡乱施用攻伐之法。
痘疮发出后，进入灌浆时期，虽然以大便秘结坚实为顺症，但如果痘出五六天仍不大便，这是毒火内侵，津液外耗，导致肠胃干枯而秘结。可用四顺饮。如果痘色苍白、精神萎靡、不思饮食、呕吐清水的，属于虚秘。可用钱乙的异功散加入当归、白芍。如果是血热口干、烦躁便秘，用四顺饮加入紫草，使其大便通畅两三次，热毒自然解除，烦躁自然平息。如果有风寒表证，先宜用解散表邪的方法，然后才可攻下。如果不先解表，恐怕表邪乘虚入里，痘疹反而潜伏不发，即使发出也不整齐，最终形成塌陷焦枯，这是必然的趋势。如在六七日灌脓之时，高热脉象盛大而大便不通，可用加味消毒饮，以及蜜煎导法来润肠通便。否则会导致腹胀气喘胸闷。有过因过度利小便，导致津液内耗而便秘的，用生脉散加入当归。另外气血俱足化成脓浆，而四五日不大便的，只宜用清凉活血之法，脓浆充足后大便自会通行，不需要特别治疗。薛己曾说：痘疹大便不通，应当分辨虚实，通过观察手足冷热，以及询问是否想喝水或喝汤来验证。
The *Classic of Internal Medicine* states: "The waist is the mansion of the Kidney." In smallpox, if lower back pain occurs, or pain radiates to the spine, making turning difficult, it is due to the emptiness of the Kidney's protective qi (Guo), hyperactivity of pathogenic fire, and the inability of True Yin to overcome the pathogen. It is urgent to use **Sishun Qingliang Yin** (Four-Obedience Cooling Decoction) with the priority of rescuing from heat and preserving Yin. If high fever and lower back pain occur suddenly before the eruption of lesions, and the facial complexion is purple-red, the lesions will inevitably become dry and purple-black. This indicates severe accumulation of Fire-Toxin in the Kidney. Urgently use **Baixiang Wan** (Hundred-Auspicious Pill) or administer **Yuanming Fen** (Mirabilite) mixed with water to purge and curb the pathogenic momentum. Subsequently, use **Xiaodu Yin** (Detoxification Decoction) added with **Fangfeng** (Saposhnikovia Root), **Zicao** (Arnebia Root), **Lianqiao** (Forsythia Fruit), and **Mutong** (Akebia Stem). If large patches of purple-black spots resembling flea bites appear below the waist, death is inevitable within seven days.
In smallpox, clear and long urination, along with loose and moist stools, are termed "Harmony of the Interior Qi" (Li Qi He). Any difficulty or obstruction leads to the internal accumulation of Toxin, causing stagnation and blockage in the intestines and stomach, preventing proper transmission and transformation. At this stage, clearing heat and resolving toxicity is appropriate; once the stool is unblocked, urination will naturally flow freely. Formulas such as **Sanhuang Wan** (Three-Yellow Pill), **Sishun Yin**, and **Qianhu Zhike Tang** (Peucedanum and Aurantium Decoction) are specifically indicated for the initial stage of smallpox eruption. However, if constipation of both stool and urine occurs during the pustule formation stage (Yang Jiang), one must examine deficiency and excess to treat accordingly. Stop medication when the disease is cured; do not overdose. If diet remains normal, bowel and bladder functions are unchanged, and internal symptoms are peaceful, neither warming tonification nor reckless attacking methods should be used.
After the eruption of smallpox, during the pus-filling stage, although firm constipation is considered a favorable sign, if there is no bowel movement for five to six days after eruption, it is due to internal invasion by Toxic Heat and external depletion of Body Fluids, leading to dryness and constipation of the intestines and stomach. Use **Sishun Yin**. If the lesions are pale, the patient lacks spirit, refuses food, and vomits clear fluid, it is Deficiency Constipation. Use **Yigong San** (Extraordinary Power Powder) by Qian Yi, added with **Danggui** (Angelica Sinensis) and **Shaoyao** (Peony Root). If there is Blood Heat, dry mouth, irritability, and constipation, use **Sishun Yin** added with **Zicao**, aiming for two to three bowel movements to resolve Toxic Heat and calm irritability. If Wind-Cold is present, first resolve the exterior, then purge the interior. If the exterior is not resolved first, pathogenic factors may enter the interior through deficiency, causing the rash to fail to erupt or erupt unevenly, leading to collapse and scorching dryness, which is an inevitable outcome. During the sixth or seventh day of pus formation, if there is high fever, surging pulse, and constipation, use **Jiawei Xiaodu Yin** (Modified Detoxification Decoction) and **Mi Jian Dao** (Honey Suppository) to moisten and purge. Otherwise, abdominal distension and wheezing will occur. For cases of constipation caused by excessive diuresis depleting internal fluids, use **Shengmai San** (Generate Pulse Powder) added with **Danggui**. Furthermore, if Qi and Blood are sufficient to form pus but there is no bowel movement for four to five days, only cooling and blood-invigorating methods are needed; once pus is sufficient, defecation will occur naturally, requiring no specific treatment. Xue Ji stated: For constipation in smallpox, one must distinguish between deficiency and excess, verifying by checking the temperature of the hands and feet and asking about the desire to drink water or soup.