虚损之由，不论酒色劳倦，七情饮食，皆能致此，而惟阴阳之辨为最要。阴虚者，其
发热躁烦，头红面赤，唇干舌燥，咽痛口疮，吐血衄血，便血尿血，大便燥结，小水痛涩等
证；阳虚者，其病则为怯寒，憔悴气短，神疲头运，目眩呕恶，食少腹痛，飧泄，二便不禁
等证。至若咳嗽吐痰，遗精盗汗，气喘声喑，筋骨疼痛，心神恍惚，肌肉渐削，梦与鬼交，
妇人月闭等症，则又无论阴阳，而凡病至甚者，皆其所必至。然肾为五脏之本，水为天一之
源，则凡患虚损者，实惟肾水之亏，十居八九。盖肾水亏则肝失所滋，而血燥生，肾水亏则
水不归源，而脾痰起；肾水亏则心肾不交，而神色败；肾水亏则盗伤肺气，而咳嗽频；肾水
亏则孤阳无主，而虚火炽。节斋先生云∶人若色欲过度，伤损精血，必生阴虚火动之病。丹
溪先生云∶凡患虚者，多阴虚也，古人岂欺我哉！
阴虚者多热，以水不济火，而阴虚生热也。欲滋其阴，惟宜甘凉醇静之物，大忌辛温
，如干姜、桂附、故纸、白术、苍术、半夏之属，断不可用。即如人参、黄 、枸杞、当归
、杜仲、菟丝之类，是皆阴中有阳，尤当斟酌。盖阳旺则阴愈消，热增则水益涸矣。然阴虚
之热，为真水之亏，寒凉之品，又不可妄用。其有火盛而不得不从寒治者，亦当兼壮水之剂
，可止即止，以防其败，斯得滋补之大法矣。
夜热或午后热，或喜冷便实，此皆阴虚生热，水不制火也，宜加减一阴煎。惊悸失志
，火在心肾也，宜二阴煎。若外热不已，而内不甚热，则但宜补阴，不宜清火，宜一阴煎，
或六味地黄汤。
虚损病的成因，无论是饮酒纵欲、劳累倦怠，还是七情内伤、饮食不节，都能导致此病，其中辨别阴阳属性最为关键。阴虚证的表现是：发热烦躁，头部发红面色赤红，嘴唇干燥舌头干涩，咽喉疼痛口腔生疮，吐血鼻出血，大便带血小便带血，大便干结难解，小便短少且排尿刺痛涩滞等症；阳虚证的表现则是：畏寒怕冷，形体憔悴气力短促，精神疲惫头晕目眩，眼睛昏花恶心呕吐，食欲减退腹部疼痛，完谷不化的泄泻，大小便失禁等症。至于咳嗽吐痰，遗精盗汗，气喘声音嘶哑，筋骨疼痛，心神恍惚不定，肌肉逐渐消瘦，梦中与鬼交合，妇女月经闭止等症状，则不论属于阴证还是阳证，凡是病情发展到严重程度的，都是这些症状必然会出现的。然而肾是五脏的根本，水是先天之气的源头，所以凡是患有虚损病的人，实际上大多是肾水亏损，占十分之八九。因为肾水亏损则肝木失去滋养，从而血燥内生；肾水亏损则水液不能归源，从而脾湿生痰；肾水亏损则心肾不交，从而神色衰败；肾水亏损则暗中损伤肺气，从而咳嗽频繁；肾水亏损则孤阳无所依附而亢盛，从而虚火炽烈。节斋先生说：“人如果色欲过度，损伤精血，必定产生阴虚火动的病症。”丹溪先生说：“凡是患虚损病的人，多是阴虚，古人难道会欺骗我们吗！”
阴虚证多表现为热象，这是因为水不能制约火，导致阴虚而生热。想要滋补其阴，只适宜使用甘凉醇静性质的药物，大忌辛温性质的药物，如干姜、桂枝、附子、补骨脂、白术、苍术、半夏这类药物，绝对不可使用。即使是人参、黄芪、枸杞、当归、杜仲、菟丝子这类药物，都属于阴中带有阳性的药物，更应当仔细斟酌使用。因为阳气旺盛则阴液更加消减，热势增加则水源更加枯竭。然而阴虚产生的热，根源在于真水的亏损，所以寒凉性质的药物，也不可以随意滥用。如果有火邪炽盛而不得不采用寒凉法治愈的情况，也应当配合滋补肾水的方剂，症状缓解即可停药，以防止损伤正气，这才是滋补的大法。
夜间发热或午后发热，或者喜欢冷饮且大便干结，这些都是阴虚生热、水不能制约火的表现，适宜使用加减一阴煎。惊悸失眠、神志失常，是火邪在心肾之间，适宜使用二阴煎。如果体表发热不止，但体内热象不明显，则只宜补阴，不宜清火，适宜使用一阴煎，或者六味地黄汤。
The etiology of deficiency consumption (Xu Sun), regardless of whether it stems from excessive alcohol and sexual indulgence, physical fatigue and overwork, or emotional disturbances and dietary irregularities, can all lead to this condition. Among these, distinguishing between Yin and Yang is the most crucial. The manifestations of Yin deficiency include: fever with restlessness, redness of the head and face, dry lips and tongue, sore throat and mouth ulcers, hematemesis (vomiting blood) and epistaxis (nosebleed), hematochezia (blood in stool) and hematuria (blood in urine), dry and hard stools, and scanty, painful, and difficult urination. The manifestations of Yang deficiency include: aversion to cold, emaciation and exhaustion, shortness of breath, mental fatigue, dizziness, vertigo, nausea and vomiting, poor appetite, abdominal pain, undigested food in stool (Sun Xie), and incontinence of both stool and urine. As for symptoms such as coughing with expectoration, seminal emission and night sweats, asthma and hoarseness, pain in bones and tendons, mental confusion, gradual wasting of muscles, dreams of sexual intercourse with spirits, and amenorrhea in women, these occur regardless of whether the syndrome is Yin or Yang; they are inevitable consequences when any disease progresses to a severe stage. However, the Kidney is the root of the five Zang organs, and Water is the source of Heavenly One (primordial essence). Therefore, in cases of deficiency consumption, the actual cause is almost always a deficiency of Kidney Water, accounting for eight or nine out of ten cases. This is because when Kidney Water is deficient, the Liver loses its nourishment, leading to dryness of Blood; when Kidney Water is deficient, Water fails to return to its source, leading to Phlegm arising from the Spleen; when Kidney Water is deficient, there is a lack of communication between the Heart and Kidney, leading to deterioration of spirit and complexion; when Kidney Water is deficient, Lung Qi is secretly damaged, leading to frequent coughing; and when Kidney Water is deficient, solitary Yang has no master, leading to blazing deficient fire. Mr. Jiezai stated: "If one indulges excessively in sexual activities, damaging Essence and Blood, one will inevitably develop diseases of Yin deficiency with moving fire." Mr. Danxi stated: "Most patients with deficiency suffer from Yin deficiency; how could the ancients deceive us!"
Yin deficiency often presents with heat signs because Water fails to control Fire, resulting in heat generated by Yin deficiency. To nourish Yin, only sweet, cool, pure, and tranquil substances should be used. Pungent and warm herbs must be strictly avoided, such as Gan Jiang (Dried Ginger), Gui Zhi (Cinnamon Twig), Fu Zi (Aconite Root), Gu Zhi Bu (Bone Setter / Psoralea Fructus), Bai Zhu (Atractylodes Macrocephala Rhizome), Cang Zhu (Atractylodes Lancea Rhizome), and Ban Xia (Pinellia Tuber); these must absolutely not be used. Even herbs like Ren Shen (Ginseng Root), Huang Qi (Astragalus Membranaceus Root), Gou Qi Zi (Goji Berry), Dang Gui (Angelica Sinensis Root), Du Zhong (Eucommia Bark), and Tu Si Zi (Dodder Seed), which possess Yang properties within Yin, require careful consideration. This is because if Yang becomes vigorous, Yin is further consumed; if heat increases, Water becomes more depleted. However, since the heat of Yin deficiency stems from a deficiency of True Water, cold and cooling herbs should also not be used recklessly. In cases where Fire is so excessive that cooling treatment is unavoidable, formulas that strengthen Water should be combined; treatment should cease as soon as possible to prevent damage to healthy Qi. This constitutes the major principle of tonification and supplementation.
Night fevers, afternoon fevers, preference for cold drinks, and solid stools are all manifestations of Yin deficiency generating heat and Water failing to control Fire; Jia Jian Yi Yin Jian (Modified One-Yin Decoction) is appropriate. Palpitations and loss of mental clarity, caused by Fire affecting the Heart and Kidney, are treated with Er Yin Jian (Two-Yin Decoction). If external heat persists but internal heat is not significant, only Yin tonification is suitable, and clearing Fire is contraindicated; Yi Yin Jian (One-Yin Decoction) or Liu Wei Di Huang Tang (Six-Ingredient Rehmannia Pill) is appropriate.