《伤寒论》原文∶少阴病，二、三日不已，至四、五日，腹痛，
小便不利，四肢沉重疼痛，自下利者，此为有水气。其人或咳，
或小便利，或下利，或呕者，真武汤主之。
【真武汤方】茯苓三两，芍药三两，生姜三两切，白术二两，附子一枚炮去皮破八片。
上五味，以水八升，煮取三升，去滓，温服七合，日三服。若咳者，加五味子半升，细辛、干姜各一两；
若小便利者，去茯苓，若下利者，去芍药，加干姜二两；若呕者，去附子，加生姜，足前成半斤。
罗东逸曰∶夫人一身制水者脾，主水者肾也。肾为胃关，聚水而从其类，倘肾中无阳，则脾之枢机虽运，
而肾之关门不开，水即欲行以无主制，故泛溢妄行而有是证也。用附子之辛温壮肾之元阳，则水有所主矣。白术
之温燥，创建中土，则水有所制矣。生姜之辛散，佐附子以补阳，于补水中寓散水之意。茯苓之渗淡，佐白
术以建土，于制水中寓利水之道焉。而尤重在芍药之苦降，其旨甚微。盖人身阳根于阴，若徒以辛热补阳，不
少佐以苦降之品，恐真阳飞越矣。芍药为春花之殿，交夏而枯，用之以极亟收散漫之阳气而归根。下利减芍药
者，以其苦降涌泻也。加干姜者，以其温中胜寒也。水寒伤肺则咳，加细辛、干姜者，胜水寒也。加五
味子者，收肺气也。小便利者，去茯苓，恐其过利伤肾也。呕者，去附子倍生姜，以其病非下焦，水停于胃，
所以不须温肾以行水，只当温胃以散水，且生姜功能止呕也。
《伤寒论》原文：少阴病（少阴经受邪所致的病证），经过两三天没有痊愈，到了四五天，出现腹痛，小便排出不畅，四肢沉重且疼痛，自发腹泻的情况，这是因为体内有水气停留。如果患者伴有咳嗽，或者小便通畅，或者腹泻加重，或者呕吐的，应当使用真武汤主治。
【真武汤方】茯苓三两，芍药三两，生姜三两切片，白术二两，附子一枚（炮制后去皮，破开成八片）。
以上五味药，用水八升，煮取三升药液，滤去药渣，每次温服七合，每日服用三次。如果咳嗽的，加五味子半升，细辛、干姜各一两；如果小便通畅的，去掉茯苓；如果腹泻的，去掉芍药，加干姜二两；如果呕吐的，去掉附子，增加生姜用量，使生姜总量达到半斤。
罗东逸说：人体中制约水液代谢的是脾脏，主持水液代谢的是肾脏。肾是胃的关口，水液聚集并随其同类运行。倘若肾中没有阳气，那么脾脏的枢机虽然运转，但肾的关门无法打开，水液想要运行却无人主宰控制，所以泛滥溢出妄行而产生上述证候。使用附子的辛温之性来壮补肾中的元阳，水液便有了主宰。白术的温燥之性，可以建立中焦脾胃之气，水液便有了制约。生姜的辛散之性，辅助附子来补益阳气，在补水的同时寓含散水之意。茯苓的渗淡之性，辅助白术来构建土气，在制约水液的同时寓含利水之道。而其中尤为重要的是芍药的苦降之性，其中的旨意非常微妙。因为人体的阳气根源于阴液，如果仅仅用辛热药物补阳，不稍加佐以苦降的药物，恐怕真阳会飞越散失。芍药是春花的殿军，入夏即枯萎，用它来紧急收敛散漫的阳气使其归根。腹泻时减去芍药，是因为它的苦降作用会导致涌泻。加入干姜，是因为它能温中散寒。水寒伤肺导致咳嗽，加入细辛、干姜，是为了战胜水寒。加入五味子，是为了收敛肺气。小便通畅的，去掉茯苓，是担心它过度利水损伤肾气。呕吐的，去掉附子加倍生姜，是因为病位不在下焦，而是水停留在胃中，所以不需要温肾来行水，只应当温胃来散水，而且生姜具有止呕的功能。
Original text from *Shanghan Lun* (Treatise on Cold Pathogenic Diseases): In Shaoyin disease (a syndrome caused by pathogenic invasion of the Shaoyin meridians), if it persists for two or three days and reaches four or five days, symptoms such as abdominal pain, difficult urination, heaviness and pain in the four limbs, and spontaneous diarrhea occur. This is due to the retention of water qi (fluid metabolism disorder). If the patient also experiences cough, clear urination, worsening diarrhea, or vomiting, Zhenwu Tang (True Warrior Decoction) should be administered.
[Formula of Zhenwu Tang] Poria cocos (Fuling) 3 liang, Paeonia lactiflora (Shaoyao) 3 liang, Zingiber officinale (Shengjiang/Fresh Ginger) 3 liang sliced, Atractodes macrocephala (Baizhu) 2 liang, Aconitum carmichaelii (Fuzi/Aconite Root) 1 piece, prepared, peeled, broken into eight slices.
The above five herbs are boiled in 8 sheng of water until reduced to 3 sheng. The dregs are removed, and the decoction is taken warm, 7 ge per dose, three times a day. If coughing occurs, add Schisandra chinensis (Wuweizi) half sheng, Asarum heterotropoides (Xixin) and Zingiber officinale (Ganjiang/Dried Ginger) one liang each; if urination is clear/profuse, remove Poria cocos; if diarrhea occurs, remove Paeonia lactiflora and add Zingiber officinale (Ganjiang/Dried Ginger) two liang; if vomiting occurs, remove Aconitum carmichaelii and increase the amount of Zingiber officinale (Shengjiang/Fresh Ginger) so that the total weight of ginger reaches half jin.
Luo Dongyi stated: In the human body, the Spleen controls water metabolism, while the Kidney governs water. The Kidney acts as the gatekeeper of the Stomach. Water accumulates and follows its kind. If there is no Yang energy in the Kidney, although the pivot mechanism of the Spleen may function, the gate of the Kidney will not open. Consequently, water attempts to flow but lacks control, leading to overflow and erratic movement, resulting in these syndromes. The use of Aconitum carmichaelii (Fuzi) with its acrid-warm nature strengthens the primordial Yang of the Kidney, thereby providing a master for the water. The warm-drying nature of Atractodes macrocephala (Baizhu) establishes the Middle Jiao (Earth element), thereby providing restraint for the water. The acrid-dispersing nature of Zingiber officinale (Shengjiang/Fresh Ginger) assists Aconitum carmichaelii (Fuzi) in tonifying Yang, embedding the intention of dispersing water within the process of replenishing water. The permeating-and-bland nature of Poria cocos (Fuling) assists Atractodes macrocephala (Baizhu) in building Earth, embedding the method of promoting diuresis within the process of restraining water. However, the most critical aspect lies in the bitter-descending nature of Paeonia lactiflora (Shaoyao), which holds profound significance. Human Yang is rooted in Yin. If one merely uses acrid-hot herbs to tonify Yang without slightly assisting with bitter-descending agents, there is a risk that the True Yang may fly away and dissipate. Paeonia lactiflora (Shaoyao) is the last flower of spring, withering upon entering summer; it is used to urgently gather scattered Yang energy and return it to its root. When diarrhea occurs, Shaoyao is reduced because its bitter-descending property causes upward surging and purging. Ganjiang (Dried Ginger) is added because it warms the middle and overcomes cold. When cold-water injures the Lung causing cough, Xixin (Asarum) and Ganjiang (Dried Ginger) are added to overcome cold-water. Wuweizi (Schisandra) is added to astringe Lung Qi. If urination is clear/profuse, Fuling (Poria) is removed to avoid excessive diuresis damaging the Kidney. In cases of vomiting, Fuzi (Aconite) is removed and Shengjiang (Fresh Ginger) is doubled because the pathology is not in the Lower Jiao, but rather water stagnates in the Stomach. Therefore, warming the Kidney to move water is unnecessary; instead, one should warm the Stomach to disperse water. Moreover, Shengjiang (Fresh Ginger) has the function of stopping vomiting.