时疫少腹满痛，为邪热结于下焦。下焦乃大肠膀胱及厥阴分界，与中焦异，亦有满而不痛、痛而不满、满痛兼
作之不同。初起满而不痛者，湿胜气滞也，槟榔、浓朴、苍术为要药。痛而不满者，手不可近，热伤厥阴血分也。
黄芩以清热，赤芍、归尾以活血，柴胡以升厥阴之气，若牵引阴器及两胯夹缝者，加秦艽即愈。满痛兼作者，不论
初起、末后，当视其前后。在前小水不利，蓄水也，四苓、猪苓、益元等方选用。在后大便不利，有燥屎也，三
承气选用。小便利而大便色黑者，蓄血也，抵当汤、桃仁承气汤选用。以大、小便之通塞为辨，固矣，亦当细察其
满痛而有硬块不可按者，属燥屎。满痛如鼓不可按而却无块者，属溺蓄脬中。满痛拒按而软者，属蓄血。以此辨之
了然矣。外有时疫末路，满而不痛，痛而不满，喜温喜按者，为虚证，当细询来路。若屡经清、下太过，当消息温
补以培养阴阳，不可执时疫为实邪热证而不变通也。然此亦十中一见耳。
上满痛诸证，乃时疫里证之大端，总属热邪内陷。在
风、寒、暑、湿诸门，则寒、热、虚、实俱有。在时疫已经传变，见于烦渴、燥热既显之后。其为热证易辨，若见
于未经传变之先，乃疫毒郁而未发，多不渴，多不发热，甚有手足反厥冷者。根据风寒治，则当温；根据时疫治，则当
清。毫厘千里，反掌生死，当于气、色、神、脉、舌苔五者，细察而详辨之。
时行疫病出现少腹部胀满疼痛，是因为邪热结聚在下焦。下焦是大肠、膀胱以及厥阴经的分界区域，与中焦不同，其表现也有胀满但不痛、疼痛但不胀满、胀满和疼痛同时出现等不同情况。
初起时表现为胀满但不痛的，是湿气偏盛导致气机阻滞，槟榔、厚朴、苍术是主要用药。
表现为疼痛但无胀满感的，患者拒按（手不可近），这是热邪损伤了厥阴经的血分。用黄芩来清热，赤芍、当归尾来活血，柴胡来升发厥阴经的气机；如果伴有牵引阴器及两胯夹缝处疼痛的，加入秦艽即可痊愈。
胀满和疼痛同时出现的，无论是在疾病初期还是末期，都应当观察大小便的情况。如果是小便不利，属于蓄水证，可选用四苓散、猪苓散、益元散等方剂。如果是大便不利，属于有燥屎内结，可选用三承气汤类方剂。如果小便通利而大便颜色发黑的，属于蓄血证，可选用抵当汤或桃仁承气汤。以大小便的通利与否作为辨别依据，固然正确，但也应当仔细察看病位胀满疼痛且有硬块、不能按压的，属于燥屎内结；胀满疼痛如鼓状、不能按压却没有硬块的，属于尿液积聚在膀胱中；胀满疼痛拒按但触感柔软的，属于蓄血。通过这样辨别，就能清晰明了。
此外，有时疫病的晚期阶段，出现胀满但不痛、疼痛但不胀满，且喜欢温热、喜欢按压的情况，这属于虚证，应当详细询问病史经过。如果之前多次使用清热、攻下法太过，应当斟酌采用温补法来培养阴阳之气，不可固执地认为时疫病都是实热邪证而不灵活变通。然而这种情况也是十例中仅见一例罢了。
上述少腹满痛的各种证候，是时疫病里证的主要方面，总归属于热邪内陷。在风、寒、暑、湿等其他门类中，则寒、热、虚、实证都有。而在时疫病中，这些症状往往出现在已经发生传变，且在烦躁口渴、燥热表现明显之后。这类热证容易辨别；但如果出现在尚未传变之前，则是疫毒郁结而未发作，大多不口渴，大多不发热，甚至有手足反而厥冷的情况。如果按照风寒治疗，就应当用温法；如果按时疫病治疗，就应当用清法。毫厘之差，千里之谬，生死只在反掌之间，应当在气色、神态、脉象、舌苔这五个方面，仔细考察并详细辨别。
In epidemic febrile diseases, fullness and pain in the lower abdomen indicate that pathogenic heat is knotting in the Lower Jiao (Lower Burner). The Lower Jiao comprises the large intestine, bladder, and the domain of the Jueyin (Liver/Pericardium) meridians; it differs from the Middle Jiao. Manifestations vary: some present with fullness without pain, pain without fullness, or both fullness and pain simultaneously.
If fullness appears without pain at the onset, it is due to dampness prevailing and qi stagnation. Areca seed (Binglang), Magnolia bark (Houpo), and Atractylodes rhizome (Cangzhu) are the essential herbs.
If pain appears without fullness, the area is intolerant to touch (refusal of pressure), indicating that heat has injured the blood level of the Jueyin meridian. Scutellaria root (Huangqin) clears heat; Red peony root (Chishao) and the tail end of Angelica sinensis root (Guiwei) invigorate blood; Bupleurum root (Chaihu) raises the qi of the Jueyin meridian. If the pain radiates to the genitalia and the creases between the thighs, adding Gentian macrophylla root (Qinjiao) will lead to recovery.
When fullness and pain occur together, regardless of whether it is at the beginning or end of the disease, one must observe the urination and defecation. If urination is difficult, it indicates water retention; formulas such as Siling San (Four-Ingredient Powder for Leaching Out Dampness), Zhuling San, or Yiyuan San may be selected. If defecation is difficult, it indicates dry stool accumulation; the Three Chengqi Decoctions (San Chengqi Tangs) may be selected. If urination is free but the stool is black, it indicates blood stasis (accumulated blood); Didang Tang or Taoren Chengqi Tang may be selected. While distinguishing based on the patency or obstruction of urination and defecation is correct, one must also carefully examine the nature of the fullness and pain: if there are hard masses that cannot be pressed, it belongs to dry stool; if the abdomen is drum-like and tender but without hard masses, it belongs to urine retention in the bladder; if it is tender and soft upon pressure, it belongs to blood stasis. By applying this differentiation, the condition becomes clear.
Furthermore, in the late stage of epidemic febrile diseases, cases may present with fullness without pain or pain without fullness, where the patient prefers warmth and pressure. These are deficiency syndromes, and a detailed inquiry into the disease history is necessary. If previous treatments involved excessive use of clearing heat and purging methods, one should consider warming and tonifying methods to nourish yin and yang. One must not rigidly adhere to the notion that epidemic diseases are always excess-heat patterns without flexibility. However, such cases are rare, occurring perhaps once in ten.
The aforementioned syndromes of lower abdominal fullness and pain constitute the major aspect of interior syndromes in epidemic febrile diseases, generally belonging to the internal collapse of heat pathogens. In categories such as wind, cold, summerheat, and dampness, cold, heat, deficiency, and excess patterns all exist. In epidemic febrile diseases, these symptoms typically appear after transmission has occurred and following obvious signs of irritability, thirst, and dry heat. Such heat syndromes are easy to differentiate. However, if they appear before transmission occurs, it indicates epidemic toxins are constrained and not yet manifesting; patients often lack thirst and fever, and may even have cold extremities (Jue). Treating according to wind-cold requires warming methods; treating according to epidemic febrile diseases requires clearing methods. A difference of a hair's breadth leads to a thousand miles of error; life and death can turn in the flip of a hand. Therefore, one must carefully observe and detail the complexion, spirit, pulse, and tongue coating to make a precise differentiation.