少阴肾经，水火之藏，邪伤其经，随人虚实，或从水化以为寒，或从火化以为热。水
化为阴寒之邪，是其本也；火化为阳热之邪，是其标也。阴邪其脉沉细而微，阳邪其
脉沉细而数。至其见证，亦各有别。阴邪但欲寐身无热，阳邪虽欲寐则多心烦。阴邪
背恶寒口中和，阳邪背恶寒则口中燥。阴邪咽痛不肿，阳邪咽痛则肿；阴邪腹痛下利
清谷，阳邪腹痛下利清水或便脓血也。阴邪外热面色赤，里寒大便利，小便白；阳邪
外寒手足厥，里热大便秘，小便赤。此少阴标本寒热之脉证也。凡从本之治，均宜温
寒回阳；从标之治，均宜攻热救阴。回阳救阴，其机甚微，总在临证详究，辨别标本
寒热，以急施其治，庶克有济，稍缓则不及矣。
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少阴之为病，脉微细，但欲寐也。
【注】
少阴肾经，阴盛之藏也。少阴受邪，则阳气微，故脉细也。卫气行阳则寤，行阴则寐
，少阴受邪，则阴盛而行阴者多，故但欲寐也。此少阴病之提纲，后凡称少阴病者，
皆指此脉证而言也。
【集注】
方有执曰：少阴肾经也，居于极下，其脉起于小趾之下。『灵枢』曰：是主所生病者
，嗜卧但欲寐。盖人肖天地，天地之气行于阳则辟而晓，行于阴则阖而夜，故人之气
行于阳则动而寤，行于阴则静而寐。凡病人但欲寐者，邪客于阴故也。
张璐曰：此言少阴之总脉总证也。盖少阴属水主静，即使热邪传至其经，在先之脉虽
浮大，此时亦必变为沉细；在先之证虽烦热不宁，此时亦必变为昏沉嗜卧。但须辨出
脉细沉数、口中燥为热证；脉沉微细、口中和为寒证，以此明辨，万无差误矣。
程应旄曰：凡阴脉皆沉，异乎太阳之浮，不必言矣。阳明脉大，微者大之反；少阳脉
弦，细者弦之反，沉兼微细，阴证定矣。
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少阴病，始得之，反发热，脉沉者，麻黄附子细辛汤主之。
【注】
少阴病，谓但欲寐也。脉沉者，谓脉不微细而沉也。今始得之，当不发热而反发热者
，是为少阴之里寒，兼有太阳之表热也。故宜麻黄附子细辛汤，温中发汗，顾及其阳
，则两感之寒邪，均得而解之矣。
【集注】
方有执曰：发热邪在表也，脉沉少阴位北而居里也，以其居里，邪在表而发热，故曰
反也，以邪在表不在里，故用麻黄以发之；以其本阴而标寒，故用附子以温之。细辛
辛温通于少阴，用之以佐主治者，以其专经而为向导也。
程知曰：三阴表法与三阳不同，三阴必以温经之药为表，而少阴尤为紧关，故用散邪
温经之剂，俾外邪之深入者可出，而内阳亦不因之外越也。
程应旄曰：一起病便发热，兼以阴经无汗，世有计日按证者，类能用麻黄而忌在附子
。不知脉沉者，由其人肾经素寒，里阳不能协应，故沉而不能浮也。沉属少阴，不可
发汗，而始得病时即发热，则兼太阳，又不得不发汗。须以附子温经助阳，托住其里
，使阳不至随汗而越，其麻黄始可合细辛用耳！
林澜曰：传邪与阴寒皆有沉脉，沉但可为病之在里，而未可专以沉为寒也。夫少阴证
中，微细而沉，与细数而沉，其为寒热之殊，盖大有别矣。
少阴肾经，是藏纳水和火的脏腑。邪气侵袭这条经脉后，会根据患者体质的虚实不同，有的转化为水化而表现为寒证，有的转化为火化而表现为热证。由水化为阴寒性质的邪气，这是少阴病的本（根本属性）；由火化为阳热性质的邪气，这是少阴病的标（外在表现）。阴寒邪气的脉象沉细且微弱，阳热邪气的脉象沉细且快速。至于其临床表现，也各有区别。阴寒邪气导致患者只想睡觉、身体没有发热；阳热邪气虽然也想睡觉，但往往伴有心烦意乱。阴寒邪气导致背部怕冷、口中感觉平和（不苦不燥）；阳热邪气导致背部怕冷、但口中干燥。阴寒邪气导致咽痛但不红肿；阳热邪气导致咽痛且红肿。阴寒邪气导致腹痛、腹泻且大便中有未消化的食物；阳热邪气导致腹痛、腹泻且排出清水或脓血便。阴寒邪气表现为体表发热、面色发红、内部寒冷、大便通畅、小便颜色清白；阳热邪气表现为体表发冷、手足冰凉、内部发热、大便秘结、小便颜色深红。这就是少阴病标本寒热的脉象和症状。凡是属于从本（寒化）治疗的，都适宜用温散寒邪、回阳救逆的方法；凡是属于从标（热化）治疗的，都适宜用攻逐热邪、救阴生津的方法。回阳和救阴的治疗时机非常微妙，关键在于临证时详细探究，辨别是标本寒热中的哪一种，从而紧急实施治疗，这样才可能取得疗效，如果稍有迟缓就来不及了。
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【注】
少阴肾经，是阴气旺盛的脏腑。少阴经受邪，阳气就会衰弱，所以脉象细弱。卫气运行于阳分则人清醒，运行于阴分则人入睡。少阴受邪，阴气盛行，运行于阴分的卫气就多，所以患者只想睡觉。这是少阴病的提纲，后世凡是提到“少阴病”的，都是指这种脉象和症状而言。
【集注】
方有执说：少阴即肾经，位于人体最下部，其经脉起于足小趾之下。《灵枢》说：该经主治所生的疾病，表现为嗜睡、只想睡觉。大概人效法天地，天地的阳气运行于阳时则开启为白天，运行于阴时则闭合为夜晚，所以人的气运行于阳时则活动而清醒，运行于阴时则安静而睡眠。凡是病人只想睡觉的，是因为邪气客居在阴分所致。
张璐说：这是在讲述少阴病的总脉象和总症状。大概少阴属水主静，即使热邪传变到这条经，之前的脉象虽然浮大，此时也必然变为沉细；之前的症状虽然烦热不安，此时也必然变为昏沉嗜卧。只须辨别出脉象细沉数、口中干燥为热证；脉象沉微细、口中平和为寒证，以此明确分辨，就不会有任何差错。
程应旄说：凡是阴脉都是沉脉，不同于太阳病的浮脉，这不必多说了。阳明病的脉大，微是大脉的反面；少阳病的脉弦，细是弦脉的反面。脉象既沉又微细，阴证就确定了。
@@@
少阴病，刚得病时，反而出现发热，脉象沉的，用麻黄附子细辛汤主治。
【注】
少阴病，是指只想睡觉的症状。脉沉，是指脉象不微细而是沉取有力。现在刚得病，应当不发热却反而发热，这是少阴里寒兼有太阳表热的情况。所以适宜用麻黄附子细辛汤，温中发汗，顾护阳气，这样两感（表里同病）的寒邪都能得到解除。
【集注】
方有执说：发热说明邪气在表，脉沉说明少阴位北而居于里。因为它居于里，邪气在表却发热，所以叫“反”。因为邪气在表不在里，所以用麻黄来发散；因为少阴本阴而标寒，所以用附子来温补。细辛辛温，通入少阴经，用它来辅助主药，是因为它专入此经作为向导。
程知说：三阴经的解表方法与三阳经不同，三阴经必须用温经的药来解表，而少阴经尤为关键，所以使用散邪温经的药剂，使深入的外邪能够外出，而内阳也不会因此向外耗散。
程应旄说：一起病就发热，加上阴经无汗，世上有些按日期和症状计论的人，往往能用麻黄却忌讳用附子。不知道脉沉的原因，是由于此人肾经素来虚寒，里阳不能协同响应，所以脉沉而不能浮。沉脉属于少阴，不可单纯发汗，但刚得病时就发热，说明兼有太阳表证，又不得不发汗。必须用附子温经助阳，托住里气，使阳气不致随汗液外泄，这时麻黄才可以配合细辛使用！
林澜说：传变的邪气和阴寒之气都有沉脉，沉脉只能说明病在里，但不能专门以沉脉定为寒证。在少阴证中，脉象微细而沉，与脉象细数而沉，它们代表的寒热差异，确实大有分别。
The Shaoyin (Lesser Yin) Kidney Meridian is the storehouse of Water and Fire. When pathogenic factors invade this meridian, they transform according to the patient's deficiency or excess: either transforming into Water to manifest as Cold, or transforming into Fire to manifest as Heat. The transformation into Water results in Yin-Cold pathogens, which constitutes the Root (Ben); the transformation into Fire results in Yang-Heat pathogens, which constitutes the Branch (Biao). The pulse for Yin pathogens is deep, fine, and faint; the pulse for Yang pathogens is deep, fine, and rapid. Their clinical manifestations also differ. Yin pathogens cause drowsiness without fever; Yang pathogens cause drowsiness accompanied by vexation. Yin pathogens cause aversion to cold in the back with a neutral mouth sensation; Yang pathogens cause aversion to cold in the back with a dry mouth. Yin pathogens cause sore throat without swelling; Yang pathogens cause sore throat with swelling. Yin pathogens cause abdominal pain with diarrhea containing undigested food; Yang pathogens cause abdominal pain with watery diarrhea or pus and blood in the stool. Yin pathogens manifest as external heat with red complexion, internal cold with loose stools, and clear urine; Yang pathogens manifest as external cold with cold limbs, internal heat with constipation, and dark urine. These are the pulses and symptoms of the Root and Branch, Cold and Heat of Shaoyin disease. Treatment based on the Root should generally use warming methods to dispel Cold and restore Yang; treatment based on the Branch should generally use purging methods to clear Heat and preserve Yin. The timing for restoring Yang and preserving Yin is critical; it depends entirely on careful clinical investigation to distinguish between Root/Branch and Cold/Heat, allowing for urgent treatment so that success may be achieved. Slight delay will render treatment ineffective.
@@@
Shaoyin disease is characterized by a faint and fine pulse, and a desire to sleep.
[Annotation]
The Shaoyin Kidney Meridian is a storehouse where Yin is abundant. When Shaoyin is invaded by pathogens, Yang Qi becomes weak, resulting in a fine pulse. Wei Qi (Defensive Qi) moves through Yang to keep one awake, and through Yin to induce sleep. When Shaoyin is invaded, Yin becomes abundant, and Wei Qi spends more time moving through Yin, causing the patient to desire sleep. This is the outline of Shaoyin disease; henceforth, whenever "Shaoyin disease" is mentioned, it refers to these specific pulses and symptoms.
[Collected Annotations]
Fang Youzhi stated: Shaoyin refers to the Kidney Meridian, located at the lowest part, originating from below the little toe. The *Ling Shu* states: It governs diseases generated within, manifesting as lethargy and a desire to sleep. Humans mirror Heaven and Earth; when the Qi of Heaven and Earth moves through Yang, it opens into day; when it moves through Yin, it closes into night. Similarly, when human Qi moves through Yang, one is active and awake; when it moves through Yin, one is quiet and asleep. Patients who only desire sleep do so because pathogens have lodged in the Yin aspect.
Zhang Lu stated: This describes the general pulse and symptom of Shaoyin. Shaoyin belongs to Water and is static. Even if Heat pathogens transmit to this meridian, a previously floating and large pulse must change to deep and fine; previously restless and hot symptoms must change to lethargy and drowsiness. One must distinguish: a deep, fine, and rapid pulse with a dry mouth indicates Heat; a deep, faint, and fine pulse with a neutral mouth sensation indicates Cold. Clear distinction here ensures no errors.
Cheng Yingmao stated: All Yin pulses are deep, differing from the floating pulse of Taiyang, which needs no further explanation. The Yangming pulse is large; "faint" is the opposite of "large." The Shaoyang pulse is wiry; "fine" is the opposite of "wirly." A pulse that is both deep and faint/fine confirms a Yin syndrome.
@@@
In Shaoyin disease, upon initial onset, there is contrary fever and a deep pulse; Ma Huang Fu Zi Xi Xin Tang (Ephedra, Aconite, and Asarum Decoction) is the primary treatment.
[Annotation]
Shaoyin disease refers to the symptom of desiring sleep. A deep pulse here means the pulse is not faint and fine but deep. Upon initial onset, fever should not be present, yet contrary fever appears. This indicates interior Cold of Shaoyin combined with exterior Heat of Taiyang. Therefore, Ma Huang Fu Zi Xi Xin Tang (Ephedra, Aconite, and Asarum Decoction) is appropriate to warm the interior and induce sweating, protecting Yang Qi, thereby resolving the Cold pathogens affecting both layers (exterior and interior).
[Collected Annotations]
Fang Youzhi stated: Fever indicates pathogens in the exterior; a deep pulse indicates Shaoyin's position in the North and interior. Because it resides in the interior, fever despite exterior pathogens is termed "contrary." Since pathogens are in the exterior, not the interior, Ma Huang (Ephedrae Herba) is used to disperse them. Because the root is Yin and the branch is Cold, Fu Zi (Aconiti Lateralis Radix Praeparata) is used to warm. Xi Xin (Asari Radix et Rhizoma) is acrid and warm, connecting to Shaoyin; it assists the principal herbs as a guide specifically entering this meridian.
Cheng Zhi stated: The method for releasing the exterior in the Three Yin meridians differs from the Three Yang. For the Three Yin, one must use warming-meridian drugs to release the exterior, with Shaoyin being particularly critical. Thus, formulas that disperse pathogens and warm the meridian are used, allowing deeply entrenched exterior pathogens to exit while preventing internal Yang from dissipating outward.
Cheng Yingmao stated: If fever occurs immediately upon onset, combined with anhidrosis typical of Yin meridians, some clinicians calculate days and symptoms, often using Ma Huang (Ephedrae Herba) while avoiding Fu Zi (Aconiti Lateralis Radix Praeparata). They fail to realize that a deep pulse arises because the person's Kidney Meridian has been chronically cold, and interior Yang cannot coordinate, making the pulse deep rather than floating. A deep pulse belongs to Shaoyin, where sweating is contraindicated. However, since fever occurs immediately upon onset, indicating concurrent Taiyang, sweating is necessary. One must use Fu Zi (Aconiti Lateralis Radix Praeparata) to warm the meridian and assist Yang, anchoring the interior so Yang does not escape with sweat, before Ma Huang (Ephedrae Herba) can be safely combined with Xi Xin (Asari Radix et Rhizoma).
Lin Lan stated: Both transmitted pathogens and Yin-Cold present with a deep pulse. Deepness indicates the disease is in the interior but does not exclusively indicate Cold. In Shaoyin syndromes, a pulse that is faint, fine, and deep differs significantly from one that is fine, rapid, and deep regarding their respective Cold and Heat natures.